Federal Register, Volume 79 Issue 130 (Tuesday, July 8, 2014) 2014 Federal Register, 79 FR 38677-38746; Centralized Library: U.S. Fish and Wildlife Service -

[Federal Register Volume 79, Number 130 (Tuesday, July 8, 2014)]
[Rules and Regulations]
[Pages 38677-38746]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-14615]

[[Page 38677]]

Vol. 79

Tuesday,

No. 130

July 8, 2014

Part II

Department of the Interior

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Fish and Wildlife Service

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50 CFR Part 17

Endangered and Threatened Wildlife and Plants; Threatened Status for
the Northern Mexican Gartersnake and Narrow-Headed Gartersnake; Final
Rule

Federal Register / Vol. 79 , No. 130 / Tuesday, July 8, 2014 / Rules
and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2013-0071: 4500030113]
RIN 1018-AY23

Endangered and Threatened Wildlife and Plants; Threatened Status
for the Northern Mexican Gartersnake and Narrow-Headed Gartersnake

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
threatened species status under the Endangered Species Act of 1973
(Act), as amended, for the northern Mexican gartersnake (Thamnophis
eques megalops) and the narrow-headed gartersnake (Thamnophis
rufipunctatus), native species from Arizona and New Mexico in the
United States. We also finalize a rule under authority of section 4(d)
of the Endangered Species Act of 1973, as amended (Act), that provides
measures that are necessary and advisable to provide for the
conservation of the northern Mexican gartersnake. Both species are
listed as threatened throughout their range, which, for the northern
Mexican gartersnake, also includes the Mexican states of Sonora,
Chihuahua, Durango, Coahuila, Zacatecas, Guanajuato, Nayarit, Hidalgo,
Jalisco, San Luis Potos[iacute], Aguascalientes, Tlaxacala, Puebla,
M[eacute]xico, Veracruz, and Quer[eacute]taro. The effect of this
regulation will be to add these species to the lists of Endangered and
Threatened Wildlife and Plants.

DATES: This rule becomes effective August 7, 2014.

ADDRESSES: This final rule is available on the internet at http://www.regulations.gov (Docket No. FWS-R2-ES-2013-0071) and http://www.fws.gov/southwest/es/arizona. Comments and materials we received,
as well as supporting documentation we used in preparing this rule, are
available for public inspection at http://www.regulations.gov. All of
the comments, materials, and documentation that we considered in this
rulemaking are available by appointment, during normal business hours
at: U.S. Fish and Wildlife Service, Arizona Ecological Services Field
Office, 2321 West Royal Palm Road, Suite 103, Phoenix, AZ 85021;
telephone: 602-242-0210; facsimile: 602-242-2513.

FOR FURTHER INFORMATION CONTACT: Steve Spangle, Field Supervisor, U.S.
Fish and Wildlife Service, Arizona Ecological Services Field Office,
2321 West Royal Palm Road, Suite 103, Phoenix, AZ 85021; telephone:
602-242-0210; facsimile: 602-242-2513. Persons who use a
telecommunications device for the deaf (TDD) may call the Federal
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule. Under the Endangered Species Act, a
species may warrant protection through listing if it is endangered or
threatened throughout all or a significant portion of its range.
Listing a species as an endangered or threatened species requires
issuing a rule. This rule will finalize the listing of the northern
Mexican gartersnake (Thamnophis eques megalops) and narrow-headed
gartersnake (Thamnophis rufipunctatus) as threatened species, initiated
with our proposed listing rule published on July 10, 2013 (78 FR
41500), and finalize a rule under authority of section 4(d) of the Act
that provides measures that are necessary and advisable to provide for
the conservation of the northern Mexican gartersnake.
The basis for our action. Under the Endangered Species Act, we can
determine that a species is an endangered or threatened species based
on any of five factors: (A) The present or threatened destruction,
modification, or curtailment of its habitat or range; (B)
Overutilization for commercial, recreational, scientific, or
educational purposes; (C) Disease or predation; (D) The inadequacy of
existing regulatory mechanisms; or (E) Other natural or manmade factors
affecting its continued existence. We have determined that predation
from and competition with nonnative species such as bass (Micropterus
sp.), flathead catfish (Pylodictis sp.), channel catfish (Ictalurus
sp.), Chihuahuan catfish (Ictalurus chihuahua), bullheads (Ameiurus
sp.), sunfish (Lepomis sp.), and crappie (Pomoxis sp.), brown trout
(Salmo trutta), American bullfrogs (Lithobates catesbeiana), and
crayfish (northern (virile) crayfish (Orconectes virilis) and red swamp
crayfish (Procambarus clarkia)) are the most significant threat
affecting these gartersnakes across their range. Throughout the
remainder of this final rule, the nonnative species identified
immediately above will be referred to collectively as ``harmful
nonnative species.'' Large-scale wildfires and land uses that divert,
dry up, or significantly pollute aquatic habitat have also been found
to be significant threats. Collectively, these threats have adversely
affected gartersnake populations, and most of their native prey
species, such that the gartersnakes' resiliency, redundancy, and
representation across their ranges have been significantly compromised.
Peer review and public comment. We sought comments from independent
specialists to ensure that our designation is based on scientifically
sound data, assumptions, and analyses. We invited these peer reviewers
to comment on our listing proposal. We also considered all other
comments and information received during the comment period on the
proposed listing rule. All comments are available at http://www.regulations.gov (Docket No. FWS-R2-ES-2013-0071).

Previous Federal Action

Please refer to the proposed listing rule for the northern Mexican
gartersnake and narrow-headed gartersnake (78 FR 41500; July 10, 2013)
for a detailed description of previous Federal actions concerning this
species.
We will also be finalizing the designation of critical habitat for
the northern Mexican gartersnake and narrow-headed gartersnake in a
separate rule in the future. Information regarding designation of
critical habitat for these species is available at http://www.regulations.gov (Docket No. FWS-R2-ES-2013-0022).

Background

Northern Mexican Gartersnake

Subspecies Description

The northern Mexican gartersnake ranges in color from olive to
olive-brown or olive-gray with three lighter-colored stripes that run
the length of the body, the middle of which darkens toward the tail.
This species may inhabit the same area as other native gartersnake
species and can be difficult for people without specific expertise to
identify. The snake may reach a maximum known length of 44 inches (in)
(112 centimeters (cm)). The pale yellow to light-tan lateral (side of
body) stripes distinguish the northern Mexican gartersnake from other
sympatric (co-occurring) gartersnake species because a portion of the
lateral stripe is found on the fourth scale row, while it is confined
to lower scale rows for other species. Paired black spots extend along
the olive dorsolateral fields (region adjacent to the top of the

[[Page 38679]]

snake's back) and the olive-gray ventrolateral fields (region adjacent
to the area of the snake's body in contact with the ground). The scales
are keeled (possessing a ridge down the center of each scale). A more
detailed subspecies description can be found in our September 26, 2006
(71 FR 56227), or November 25, 2008 (73 FR 71788) 12-month findings for
this subspecies, or by reviewing Rosen and Schwalbe (1988, p. 4),
Rossman et al. (1996, pp. 171-172), Ernst and Ernst (2003, pp. 391-
392), or Manjarrez and Garcia (1993, pp. 1-5).

Taxonomy

The northern Mexican gartersnake (Thamnophis eques megalops) is a
member of the family Colubridae and subfamily Natricinae (harmless
live-bearing snakes) (Lawson et al. 2005, p. 596; Pyron et al. 2013, p.
31). The taxonomy of the genus Thamnophis has a complex history, partly
because many of the species are similar in appearance and arrangement
of scales and many of the early museum specimens were in such poor and
faded condition that it was difficult to study them (Conant 2003, p.
6).
Prior to 2003, Thamnophis eques was considered to have three
subspecies, T. e. eques, T. e. megalops, and T. e. virgatenuis (Rossman
et al. 1996, p. 175). In 2003, an additional seven new subspecies were
identified under T. eques: (1) T. e. cuitzeoensis; (2) T. e.
patzcuaroensis; (3) T. e. insperatus; (4) T. e. obscurus; (5) T. e.
diluvialis; (6) T. e. carmenensis; and (7) T. e. scotti (Conant 2003,
p. 3). Common names were not provided, so in this final rule, we use
the scientific name for all subspecies of Mexican gartersnake other
than the northern Mexican gartersnake. These seven new subspecies were
described based on morphological differences in coloration and pattern,
have highly restricted distributions, and occur in isolated wetland
habitats within the mountainous Transvolcanic Belt region of southern
Mexico, which contains the highest elevations in the country (Conant
2003, pp. 7-8). Additional information regarding this subspecies'
taxonomy can be found in de Queiroz et al. (2002, p. 323), de Queiroz
and Lawson (1994, p. 217), Rossman et al. (1996, pp. xvii-xviii, 171-
175), Rosen and Schwalbe (1988, pp. 2-3), Liner (1994, p. 107), and
Crother et al. (2012, p. 70). A description of the taxonomy of the
northern Mexican gartersnake is found in our September 26, 2006 (71 FR
56227) and November 25, 2008 (73 FR 71788) 12-month findings for this
subspecies.

Habitat and Natural History

Throughout its rangewide distribution, the northern Mexican
gartersnake occurs at elevations from 130 to 8,497 feet (ft) (40 to
2,590 meters (m)) (Rossman et al. 1996, p. 172) and is considered a
``terrestrial-aquatic generalist'' (Drummond and Marc[iacute]as-
Garc[iacute]a 1983, pp. 24-26). The northern Mexican gartersnake is a
riparian obligate (generally found in riparian areas when not engaged
in dispersal, gestation, or hibernation behaviors) and occurs chiefly
in the following general habitat types: (1) Small, often isolated
wetlands (e.g., cienegas (mid-elevation wetlands with highly organic,
reducing (basic or alkaline) soils), or stock tanks (small earthen
impoundment)); (2) large-river riparian woodlands and forests; and (3)
streamside gallery forests (as defined by well-developed broadleaf
deciduous riparian forests with limited, if any, herbaceous ground
cover or dense grass) (Hendrickson and Minckley 1984, p. 131; Rosen and
Schwalbe 1988, pp. 14-16). Emmons and Nowak (2013, p. 14) found this
subspecies most commonly in protected backwaters, braided side channels
and beaver ponds, isolated pools near the river mainstem, and edges of
dense emergent vegetation that offered cover and foraging opportunities
when surveying in the upper and middle Verde River region. Additional
information on the habitat requirements of the northern Mexican
gartersnake within the United States and Mexico can be found in our
2006 (71 FR 56227) and 2008 (73 FR 71788) 12-month findings for this
subspecies and in Rosen and Schwalbe (1988, pp. 14-16), Rossman et al.
(1996, p. 176), McCranie and Wilson (1987, pp. 11-17), Ernst and Ernst
(2003, p. 392), and Cirett-Galan (1996, p. 156).
The northern Mexican gartersnake is surface active at ambient (air)
temperatures ranging from 71 degrees Fahrenheit ([deg]F) to 91 [deg]F
(22 degrees Celsius ([deg]C) to 33 [deg]C) and forages along the banks
of waterbodies (Rosen 1991, p. 305, Table 2). While conducting visual
surveys, Rosen (1991, pp. 308-309) found that northern Mexican
gartersnakes spent up to 60 percent of their time moving, 13 percent of
their time basking on vegetation, 18 percent of their time basking on
the ground, and 9 percent of their time under surface cover. However,
preliminary telemetry data from a population of northern Mexican
gartersnakes at the Bubbling Ponds State Fish Hatchery show individuals
were surface active during 16 percent of telemetry observations, not
surface active during 64 percent of telemetry observations, and surface
activity was undetermined for 20 percent of the telemetry observations
(Boyarsky 2013, pers. comm.); at Tavasci Marsh along the upper Verde
River, they were inactive 60 percent of the time (Emmons 2013b, pers.
comm.). In the northern-most part of its range, the northern Mexican
gartersnake appears to be most active during July and August, followed
by June and September (Emmons and Nowak 2013, p. 14). Northern Mexican
gartersnakes may use different sites as hibernacula during a single
cold-season and will bask occasionally (Emmons 2014, pers. comm.).
Although considered a highly aquatic species, the northern Mexican
gartersnake uses terrestrial habitat for hibernation (Young and
Boyarski 2012b, pp. 25-28), gestation, seeking mates, and dispersal.
Along the middle Verde River preliminary telemetry data for the
northern Mexican gartersnake found that the species may travel at least
528 feet (161 m) from the nearest water and as much as 0.4 mi (0.6 km)
in a single day (total distance traveled) (Emmons 2014, pers. comm.).
Terrestrial habitat use in open, grassland-dominated landscapes with
scattered livestock tanks, such as in southern Arizona, may reflect
that greater distances are traveled as suggested by the observation of
a large female northern Mexican gartersnake observed in O'Donnell
Canyon, which was far from source populations and may have been
dispersing overland (Rosen and Schwalbe 1988, p. 14). Preliminary data
from the population at Bubbling Ponds State Fish Hatchery show that
home ranges vary from 1.7 acres (0.7 ha) to 10.4 acres (4.2 ha), with a
mean home range size of 6.2 acres (2.51 ha) (Young and Boyarski 2012b,
p. 23).
The northern Mexican gartersnake is an active predator and depends
on smaller animals for its prey base (Rosen and Schwalbe 1988, pp. 18,
20). Northern Mexican gartersnakes forage along vegetated banklines,
searching for prey in water and on land, using different strategies
(Alfaro 2002, p. 209), or may forage along the edges of open water and
thick stands of vegetation such as cattails. Generally, its diet
consists of native amphibians and fishes, such as adult and larval
(tadpoles) native leopard frogs (e.g., lowland leopard frog (Lithobates
yavapaiensis) and Chiricahua leopard frog (Lithobates chiricahuensis)),
as well as juvenile and adult native fish species (e.g., Gila topminnow
(Poeciliopsis occidentalis occidentalis), desert pupfish (Cyprinodon
macularius), Gila chub (Gila intermedia), and roundtail chub (Gila
robusta)) (Rosen and

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Schwalbe 1988, p. 18). Drummond and Marc[iacute]as-Garc[iacute]a (1983,
pp. 25, 30) found that as a subspecies, Mexican gartersnakes fed
primarily on frogs. The northern Mexican gartersnake may congregate at
ephemeral amphibian breeding ponds to exploit high-density prey
populations as observed at New Mexican spadefoot toads (Spea
multiplicata) breeding sites (d'Orgeix et al. 2013, pp. 213-215).
Auxiliary prey items may also include young Woodhouse's toads (Anaxyrus
woodhousei), treefrogs (Family Hylidae), earthworms, deermice
(Peromyscus spp.), lizards of the genera Aspidoscelis and Sceloporus,
larval tiger salamanders (Ambystoma tigrinum), and leeches (Rosen and
Schwalbe 1988, p. 20; Holm and Lowe 1995, pp. 30-31; Degenhardt et al.
1996, p. 318; Rossman et al. 1996, p. 176; Manjarrez 1998, p. 465).
Salamanders (Ambystoma spp.) may be particularly important as prey for
northern Mexican gartersnake populations in northern Mexico, both at
lower elevations and along the Sierra Madre Occidental (Lemos-Espinal
2013, pers. comm.).
In situations where native prey species are rare or absent, this
snake's diet may be almost completely comprised of nonnative species,
including larval and juvenile bullfrogs (Lithobates catesbeianus),
mosquitofish (Gambusia affinis) (Holycross et al. 2006, p. 23), or
subadult green sunfish, bluegill, or largemouth bass (Emmons and Nowak
2013, p. 5; Emmons 2013a, pers. comm.). The most recent observations of
northern Mexican gartersnakes attempting to eat predatory fish was
discussed in Emmons and Nowak (2013, p. 6) where they found fish inside
traps with gartersnakes, and the fish appeared to have been partially
consumed and then regurgitated. These observations suggest that, while
northern Mexican gartersnakes may attempt to eat predatory fish (at
least in the artificial confines of a wire trap), they may often be
spontaneously regurtitated, potentially causing harm to the snake
(Nowak and Santana-Bendix 2002, p. 24), and may not be compatible prey
for northern Mexican gartersnakes. Interestingly, in a 2012 trapping
effort along the upper Santa Cruz River, minnow traps that become self-
baited with bullfrogs, mosquitofish, or macroinvertebrates captured
snakes, but those which contained green sunfish or largemouth bass
never caught a single northern Mexican gartersnake (Lashway 2012, p.
6).
Chinese mystery snails (Cipangopaludina chinensis) have also been
reported as a prey item for northern Mexican gartersnakes at the Page
Springs and Bubbling Ponds State Fish Hatcheries in Arizona, but some
predation attempts on snails have proven fatal for gartersnakes because
of their lower jaw becoming permanently lodged in the snails' shell
(Young and Boyarski 2012a, p. 498). Venegas-Barrera and Manjarrez
(2001, p. 187) reported the first observation of a snake in the natural
diet of any species of Thamnophis after documenting the consumption of
a Mexican alpine blotched gartersnake (Thamnophis scalaris) by a
Mexican gartersnake (T. eques; subspecies not reported); a behavior
termed ophiophagy. Ophiophagy has not been specifically reported in
northern Mexican gartersnakes, although they are a subspecies of the
Mexican gartersnake.
Marc[iacute]as-Garc[iacute]a and Drummond (1988, pp. 129-134)
sampled the stomach contents of Mexican gartersnakes and the prey
populations at (ephemeral) Lake Tecocomulco, Hidalgo, Mexico. Field
observations indicated, with high statistical significance, that larger
Mexican gartersnakes fed primarily upon aquatic vertebrates (fishes,
frogs, and larval salamanders) and leeches, whereas smaller Mexican
gartersnakes fed primarily upon earthworms and leeches (Marc[iacute]as-
Garc[iacute]a and Drummond 1988, p. 131). Marc[iacute]as-Garc[iacute]a
and Drummond (1988, p. 130) also found that the birth of newborn T.
eques tended to coincide with the annual peak density of annelids
(earthworms and leeches). There is also preliminary evidence that birth
may coincide with a pronounced influx of available prey in a given
area, especially with that of explosive breeders, such as toads, but
more research is needed to confirm such a relationship (Boyarski 2012,
pers. comm.). Positive correlations were also made with respect to
capture rates (which are correlated with population size) of T. eques
to lake levels and to prey scarcity; that is, when lake levels were low
and prey species scarce, Mexican gartersnake capture rates declined
(Marc[iacute]as-Garc[iacute]a and Drummond 1988, p. 132). While prey
scarcity could have driven snakes to become active or take shelter
underground, their results suggest the importance of available water
and an adequate prey base to maintaining viable populations of Mexican
gartersnakes. Marc[iacute]as-Garc[iacute]a and Drummond (1988, p. 133)
found that, while certain prey items were positively associated with
size classes of snakes, the largest of specimens consume any prey
available.
Native predators of the northern Mexican gartersnake include birds
of prey, other snakes (kingsnakes (Lampropeltis sp.), whipsnakes
(Coluber sp.), regal ring-necked snakes (Diadophis punctatus regalis),
etc.), wading birds, mergansers (Mergus merganser), belted kingfishers
(Megaceryle alcyon), raccoons (Procyon lotor), skunks (Mephitis sp.),
and coyotes (Canis latrans) (Rosen and Schwalbe 1988, pp. 18, 39;
Brennan et al. 2009, p. 123). Historically, large, highly predatory
native fish species such as Colorado pikeminnow (Ptychocheilus lucius)
may have preyed upon northern Mexican gartersnake where the subspecies
co-occurred. Native chubs (Gila sp.) may also prey on neonatal
gartersnakes, but has not been documented in the literature to our
knowledge.
Sexual maturity in northern Mexican gartersnakes occurs at 2 years
of age in males and at 2 to 3 years of age in females (Rosen and
Schwalbe 1988, pp. 16-17). Northern Mexican gartersnakes are viviparous
(bringing forth living young rather than eggs). Mating has been
documented in April and May followed by the live birth of between 7 and
38 newborns (average is 13.6) in June, July, and August (Rosen and
Schwalbe 1988, p. 16; Nowak and Boyarski 2012, pp. 351-352; Boyarski
2013, pers. comm.). However, field observations in Arizona provide
preliminary evidence that mating may also occur during the fall, but
further research is required to confirm this hypothesis (Boyarski 2012,
pers. comm.). Unlike other gartersnake species, which typically breed
annually, one study suggests that only half of the sexually mature
females within a population of northern Mexican gartersnake might
reproduce in any one season (Rosen and Schwalbe 1988, p. 17). We found
no information on the longevity of northern Mexican gartersnakes but
presume they may live as long as 10 years in the wild.

Historical Distribution

Within the United States, the northern Mexican gartersnake
historically occurred predominantly in Arizona at elevations ranging
from 130 to 6,150 ft (40 to 1,875 m). It was generally found where
water was relatively permanent and supported suitable habitat. The
northern Mexican gartersnake has been documented historically in every
county and nearly every subbasin within Arizona, but its historical
distribution was essentially the southern two-thirds of Arizona. It was
known from several perennial or intermittent creeks, streams, and
rivers as well as lentic (still, non-flowing water) wetlands such as
cienegas, ponds, or stock tanks. Records documenting northern Mexican

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gartersnake exist within the following subbasins in Arizona: Colorado
River, Bill Williams River, Agua Fria River, Salt River, Tonto Creek,
Verde River, Santa Cruz River, Cienega Creek, San Pedro River,
Babocomari River, and the Rio San Bernardino (Black Draw) (Woodin 1950,
p. 40; Nickerson and Mays 1970, p. 503; Bradley 1986, p. 67; Rosen and
Schwalbe 1988, Appendix I; 1995, p. 452; 1997, pp. 16-17; Holm and Lowe
1995, pp. 27-35; Sredl et al. 1995b, p. 2; 2000, p. 9; Rosen et al.
2001, Appendix I; Holycross et al. 2006, pp. 1-2, 15-51; Brennan and
Holycross 2006, p. 123; Radke 2006, pers. comm.; Rosen 2006, pers.
comm.; Holycross 2006, pers. comm.; Cotton et al. 2013, p. 111).
Numerous records for the northern Mexican gartersnake (through 1996) in
Arizona are maintained in the Arizona Game and Fish Department's (AGFD)
Heritage Database (1996a).
Historically, the northern Mexican gartersnake had a limited
distribution in New Mexico that consisted of scattered locations
throughout the Upper Gila River watershed in Grant and western Hidalgo
Counties, including the Upper Gila River, Mule Creek in the San
Francisco River subbasin, and the Mimbres River (Price 1980, p. 39;
Fitzgerald 1986, Table 2; Degenhardt et al. 1996, p. 317; Holycross et
al. 2006, pp. 1-2).
One record for the northern Mexican gartersnake exists for the
State of Nevada, opposite Fort Mohave, in Clark County along the shore
of the Colorado River that was dated 1911 (De Queiroz and Smith 1996,
p. 155). The subspecies may have occurred historically in the lower
Colorado River region of California, although we were unable to verify
any museum records for California. Any populations of northern Mexican
gartersnakes that may have historically occurred in either Nevada or
California were likely associated directly with the Colorado River, and
we believe the northern Mexican gartersnake to be currently extirpated
in Nevada and California.
Within Mexico, northern Mexican gartersnakes historically occurred
within the Sierra Madre Occidental and the Mexican Plateau in the
Mexican states of Sonora, Chihuahua, Durango, Coahuila, Zacatecas,
Guanajuato, Nayarit, Hidalgo, Jalisco, San Luis Potos[iacute],
Aguascalientes, Tlaxacala, Puebla, M[eacute]xico, Veracruz, and
Quer[eacute]taro, comprising approximately 85 percent of the total
rangewide distribution of the subspecies (Conant 1963, p. 473; 1974,
pp. 469-470; Van Devender and Lowe 1977, p. 47; McCranie and Wilson
1987, p. 15; Rossman et al. 1996, p. 173; Lemos-Espinal et al. 2004, p.
83). We are not aware of any systematic, rangewide survey effort for
the northern Mexican gartersnake in Mexico. Therefore, we use other
related ecological surrogates (such as native freshwater fish) to
inform discussion on the status of aquatic communities and aquatic
habitat in Mexico, and therefore on the likely status of northern
Mexican gartersnake populations. We believe that gartersnakes and
native fish are closely ecologically connected because of the high
level of dependency of the gartersnakes on the fish as a food source.
This discussion is found below in the subheadings pertinent to Mexico.

Current Distribution and Population Status

Data on population status of northern Mexican gartersnakes in the
United States are largely summarized in unpublished agency reports. In
our literature review we found that reductions in range and population
densities have affected the status of the northern Mexican gartersnake
significantly in the last 30 years. We found that, in as much as 90
percent of the northern Mexican gartersnakes' historical distribution
in the United States, the subspecies occurs at low to very low
population densities or may even be extirpated. For example, Holycross
et al. (2006, p. 66) detected the northern Mexican gartersnake at only
2 of 11 historical localities within the northern-most part of its
range in the United States. The degraded status of the northern Mexican
gartersnake, in a rangewide context, is primarily the result of
predation by and competition with harmful nonnative species, that have
been legally released, illegally released, or have naturally dispersed
(explained below). However, ecological circumstances and potential
threats vary from site to site, and the same threats do not affect
every population with the same magnitude across their range. Regardless
of how they got into the wild, harmful nonnative species are now
widespread and present throughout the range of the northern Mexican
gartersnake. Land uses that result in the dewatering of habitat,
combined with increasing drought, have destroyed significant amounts of
habitat throughout the northern Mexican gartersnake's range and have,
therefore, reduced its distribution within several subbasins.
Where northern Mexican gartersnakes are locally abundant, they are
usually reliably detected with significantly less effort than
populations characterized as having low densities. Northern Mexican
gartersnakes are well-camouflaged, secretive, and can be very difficult
to detect in structurally complex, dense habitat (Emmons and Nowak
2013, p. 13) or where they occur at very low population densities,
which characterizes most occupied sites in lotic habitat. We considered
factors such as the date of the last known records for northern Mexican
gartersnakes in an area, as well as records of one or more native prey
species in making a conclusion on occupancy of the subspecies. We used
the year 1980 to qualify occupancy because the 1980s marked the first
systematic survey efforts for northern Mexican gartersnakes across
their range in the United States (see Rosen and Schwalbe (1988, entire)
and Fitzgerald (1986, entire)) and the last, previous records were
often dated several decades prior and may not accurately represent the
likelihood for current occupation. Several areas where northern Mexican
gartersnakes were known to occur have received no, or very little,
survey effort in the past several decades. Variability in survey design
and effort makes it difficult to compare population sizes or trends
among sites and between sampling periods. For each of the sites
discussed in Appendix A (available at http://www.regulations.gov,
Docket No. FWS-R2-ES-2013-0071), we have attempted to translate and
quantify search and capture efforts into comparable units (i.e.,
person-search hours and trap-hours) and have cautiously interpreted
those results. Because the presence of suitable prey species in an area
may provide evidence that the northern Mexican gartersnake may still
persist in low density where survey data are sparse, a record of a
native prey species was considered in our determination of occupancy of
this subspecies.
Currently, there are only five northern Mexican gartersnake
populations in the United States, where the subspecies remains reliably
detected and is considered viable, and all are located in Arizona. The
five known populations are: (1) The Page Springs and Bubbling Ponds
State Fish Hatcheries along Oak Creek, (2) lower Tonto Creek, (3) the
upper Santa Cruz River in the San Rafael Valley, (4) the Bill Williams
River, and (5) the upper and middle Verde River. In New Mexico, the
northern Mexican gartersnake was last documented in 2013 along the Gila
River in the vicinity of the Highway 180 crossing (Hotle 2013, entire)
and is considered to occur in extremely low population densities within
its historical distribution along the Gila River and Mule Creek. While

[[Page 38682]]

historically known to occur on tribal lands, the status of the northern
Mexican gartersnake on tribal lands, such as those owned by the White
Mountain or San Carlos Apache Tribes, is poorly known due to limited
survey access. As stated previously, less is known specifically about
the current distribution of the northern Mexican gartersnake in Mexico
due to limited access to information on survey efforts and field data
from Mexico.
In Table 1 below, we summarize the population status of northern
Mexican gartersnakes at all known 29 historical localities throughout
their United States distribution, as supported by museum records or
reliable observations. We categorized each population as either likely
viable, likely not viable, or likely extirpated based on the historical
survey records, suitable habitat, presence of native prey species, and
the presence of harmful nonnative species. For a detailed discussion
that explains the rationale for site-by-site conclusions on occupancy,
please see Appendix A (available at http://www.regulations.gov, Docket
No. FWS-R2-ES-2013-0071). General rationale is provided in the
introductory paragraph to this section, ``Current Distribution and
Population Status.''

Table 1--Current Population Status of the Northern Mexican Gartersnake in the United States
[References for This Information Are Provided in Appendix A]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Suitable physical Native prey species Harmful nonnative
Location Last record habitat present present species present Population status
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gila River (NM, AZ)............... 2013.................. Yes................... Yes................... Yes.................. Likely not viable.
Spring Canyon (NM)................ 1937.................. Yes................... Possible.............. Likely............... Likely extirpated.
Mule Creek (NM)................... 1983.................. Yes................... Yes................... Yes.................. Likely not viable.
Mimbres River (NM)................ Likely early 1900s.... Yes................... Yes................... Yes.................. Likely extirpated.
Lower Colorado River (AZ)......... 1904.................. Yes................... Yes................... Yes.................. Likely extirpated.
Bill Williams River (AZ).......... 2012.................. Yes................... Yes................... Yes.................. Likely viable.
Agua Fria River (AZ).............. 1986.................. Yes................... Yes................... Yes.................. Likely not viable.
Little Ash Creek (AZ)............. 1992.................. Yes................... Yes................... Yes.................. Likely not viable.
Lower Salt River (AZ)............. 1964.................. Yes................... Yes................... Yes.................. Likely extirpated.
Black River (AZ).................. 1982.................. Yes................... Yes................... Yes.................. Likely not viable.
Big Bonito Creek (AZ)............. 1986.................. Yes................... Yes................... Yes.................. Likely not viable.
Tonto Creek (AZ).................. 2005.................. Yes................... Yes................... Yes.................. Likely viable.
Upper Verde River (AZ)............ 2012.................. Yes................... Yes................... Yes.................. Likely viable.
Oak Creek (AZ).................... 2012.................. Yes................... Yes................... Yes.................. Likely viable.
(Page Springs and Bubbling Ponds
State Fish Hatcheries).
Spring Creek (AZ)................. 1986.................. Yes................... Yes................... Yes.................. Likely not viable.
Sycamore Creek (Yavapai/Coconino 1954.................. Yes................... Possible.............. Yes.................. Likely extirpated.
Co., AZ).
Upper Santa Cruz River/San Rafael 2013.................. Yes................... Yes................... Yes.................. Likely viable.
Valley (AZ).
Redrock Canyon (AZ)............... 2008.................. Yes................... Yes................... Yes.................. Likely not viable.
Sonoita Creek (AZ)................ 2013.................. Yes................... Possible.............. Yes.................. Likely not viable.
Scotia Canyon (AZ)................ 2009.................. Yes................... Yes................... No................... Likely not viable.
Parker Canyon (AZ)................ 1986.................. Yes................... Possible.............. Yes.................. Likely not viable.
Las Cienegas National Conservation 2012.................. Yes................... Yes................... Possible............. Likely not viable.
Area and Cienega Creek Natural
Preserve (AZ).
Lower Santa Cruz River (AZ)....... 1956.................. Yes................... Yes................... Yes.................. Likely extirpated.
Buenos Aires National Wildlife 2000.................. Yes................... Yes................... Yes.................. Likely not viable.
Refuge (AZ).
Bear Creek (AZ)................... 1987.................. Yes................... Yes................... Yes.................. Likely not viable.
San Pedro River (AZ).............. 1996.................. Yes................... Yes................... Yes.................. Likely not viable.
Babocomari River and Cienega (AZ). 1986.................. Yes................... Possible.............. Yes.................. Likely not viable.
Canelo Hills-Sonoita Grasslands 2012.................. Yes................... Yes................... Yes.................. Likely not viable.
Area (AZ).

[[Page 38683]]

San Bernardino National Wildlife 1997.................. Yes................... Yes................... Yes.................. Likely not viable.
Refuge (AZ).
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: ``Possible'' means there were no conclusive data found. ``Likely extirpated'' means the last record for an area pre-dated 1980, and existing
threats suggest the species is likely extirpated. ``Likely not viable'' means there is a post-1980 record for the species, it is not reliably found
with minimal to moderate survey effort, and threats exist which suggest the population may be low density or could be extirpated, but there is
insufficient evidence to support extirpation. ``Likely viable'' means that the species is reliably found with minimal to moderate survey effort, and
the population is generally considered to be somewhat resilient.

We conclude that as many as 24 of 29 known northern Mexican
gartersnake localities in the United States (83 percent) are likely not
viable and may exist at low population densities that could be
threatened with extirpation or may already be extirpated. In most
localities where the species may occur at low population densities,
existing survey data are insufficient to support a conclusion of
extirpation. Only five populations of northern Mexican gartersnakes in
the United States are considered likely viable where the species
remains reliably detected. In our November 25, 2008, 12-month finding,
we evaluated the total number of stream miles in the United States that
historically supported the northern Mexican gartersnake that are now
permanently dewatered (except in the case of temporary flows in
response to heavy precipitation), and we concluded that the subspecies
has been extirpated from or occurs at low densities in as much as 90
percent of its historical range in the United States (73 FR 71788, pp.
71792-71793). As shown in Table 1, harmful nonnative species are
present in all but one northern Mexican gartersnake locality in the
United States.
The northern Mexican gartersnake is listed as threatened throughout
its range in Mexico by the Mexican Government. However, our
understanding of the northern Mexican gartersnake's specific population
status throughout its range in Mexico is less precise than that known
for its United States distribution because survey efforts are less and
available records do not exist or are difficult to obtain for many
regions. Some specific geographic distribution records for the Mexican
states of Sonora, Chihuahua, and San Luis Potos[iacute] were presented
in Lemos-Espinal (2013, pers. comm.). Lemos-Espinal (2013 pers. comm),
a Mexican herpetologist whose work is focused on the states of Sonora,
Chihuahua, and Coahuila, commented that the number and magnitude of
threats are not equal across the subspecies' range in Mexico. Habitat
alteration or removal, as a circumstance of human population growth in
Mexico, is reported as a primary concern for populations that occur in
the Sierra Madre Occidental (Lemos-Espinal 2013, pers. comm.). In other
regions of Mexico, such as the states of Sonora and Chihuahua, Lemos-
Espinal (2013, pers. comm.) observed the northern Mexican gartersnake
to be quite common. Another gartersnake researcher from Mexico has
observed the decline or disappearance of some populations in central
Mexico (Manjerrez 2008).

Narrow-Headed Gartersnake

Species Description

The narrow-headed gartersnake is a small to medium-sized
gartersnake with a maximum total length of 44 in (112 cm) (Painter and
Hibbitts 1996, p. 147). Its eyes are set high on its unusually
elongated head, which narrows to the snout, and it lacks striping on
the dorsum (top) and sides, which distinguishes its appearance from
other gartersnake species with which it could co-occur (Rosen and
Schwalbe 1988, p. 7). The base color is usually tan or grey-brown (but
may darken) with conspicuous brown, black, or reddish spots that become
indistinct towards the tail (Rosen and Schwalbe 1988, p. 7; Boundy
1994, p. 126). The scales are keeled. Degenhardt et al. (1996, p. 327),
Rossman et al. (1996, pp. 242-244), and Ernst and Ernst (2003, p. 416)
further describe the species.

Taxonomy

We recognize the narrow-headed gartersnake, Thamnophis
rufipunctatus, as a monotypic species (no currently recognized
subspecies exist). The narrow-headed gartersnake is a member of the
family Colubridae and subfamily Natricinae (harmless live-bearing
snakes) (Lawson et al. 2005, p. 596). The taxonomy of the genus
Thamnophis has a complex history partly because many of the species are
similar in appearance and scutelation (arrangement of scales) and
because many of the early museum specimens were in such poor and faded
condition that it was difficult to study them (Conant 2003, p. 6).
There are approximately 30 species described in the gartersnake genus
Thamnophis (Rossman et al. 1996, pp. xvii-xviii). Two large overlapping
clades (related taxonomic groups) of gartersnakes have been identified
called the ``Mexican'' and ``widespread'' clades, supported by allozyme
and mitochondrial DNA genetic analyses (de Queiroz et al. 2002, p.
321). The narrow-headed gartersnake (Thamnophis rufipunctatus) is a
member of the ``Mexican'' clade and is most closely related
taxonomically to the southern Durango spotted gartersnake (Thamnophis
nigronuchalis) (de Queiroz and Lawson 1994, p. 217; de Queiroz et al.
2002; p. 321).
Due to the narrow-headed gartersnake's morphology and feeding
habits, there has been considerable deliberation among taxonomists
about the correct association of this species within seven various
genera over time (Rosen and Schwalbe 1988, pp. 5-6); chiefly, between
the genera Thamnophis (the ``gartersnakes'') and Nerodia (the
``watersnakes'') (Pierce 2007, p. 5). Chaisson and Lowe (1989, pp. 110-
118) argued that the pattern of ultrastructural (as revealed by an
electron microscope) pores in the scales of narrow-headed gartersnakes
provided evidence that the species is more appropriately placed within
the genus Nerodia. However, De Queiroz and Lawson (1994, p. 217)
rejected this premise using mitochondrial DNA (mtDNA) genetic analyses
to refute the inclusion of the narrow-headed gartersnake in the genus
Nerodia and maintain the species within the genus Thamnophis.
The narrow-headed gartersnake was first described as Chilopoma
rufipunctatum by E. D. Cope (in Yarrow, 1875). Recently, Thamnophis

[[Page 38684]]

rufipunctatus nigronuchalis and T. r. unilabialis were recognized as
subspecies under T. rufipunctatus and comprised what was considered the
T. rufipunctatus complex (Rossman et al. 1996, p. 245). However,
Rossman et al. (1996, pp. 244-246) elevated T. r. nigronuchalis to full
species designation and argued that recognition of T. r. unilabialis be
discontinued due to the diagnostic differences being too difficult to
discern. Wood et al. (2011, p. 14) used genetic analysis of the T.
rufipunctatus complex to propose the elevation of these three formerly
recognized subspecies as three distinct species, as a result of a
combination of interglacial warming, ecological and life-history
constraints, and genetic drift, which promoted differentiation of these
three species throughout the warming and cooling periods of the
Pleistocene epoch (Wood et al. 2011, p. 15). We use these most recent
and complete data in acknowledging these three entities as unique
species: T. rufipunctatus (along the Mogollon Rim of Arizona and New
Mexico, the narrow-headed gartersnake, which is the subject of this
rule), T. unilabialis (Chihuahua, eastern Sonora, and northern Durango,
Mexico), and T. nigronuchalis (southern Durango, Mexico).
Several common names have been used for this species including the
red-spotted gartersnake, the brown-spotted gartersnake, and the
currently used, narrow-headed gartersnake (Rosen and Schwalbe 1988, p.
5). Further discussion of the taxonomic history of the narrow-headed
gartersnake is available in Crother (2012, p. 71), Degenhardt et al.
(1996, p. 326), Rossman et al. (1996, p. 244), De Queiroz and Lawson
(1994, pp. 213-229), Rosen and Schwalbe (1988, pp. 5-7), and De Queiroz
et al. (2002, p. 321).

Habitat and Natural History

The narrow-headed gartersnake, distributed across the Mogollon Rim
of Arizona and New Mexico, is widely considered to be one of the most
aquatic of the gartersnakes (Drummond and Marcias Garcia 1983, pp. 24,
27; Rossman et al. 1996, p. 246). This species is strongly associated
with clear, rocky streams, using predominantly pool and riffle habitat
that includes cobbles and boulders (Rosen and Schwalbe 1988, pp. 33-34;
Degenhardt et al. 1996, p. 327; Rossman et al. 1996, p. 246; Nowak and
Santana-Bendix 2002, pp. 26-37; Ernst and Ernst 2003, p. 417). Rossman
et al. (1996, p. 246) also note the species has been observed using
lake shoreline habitat in New Mexico. Narrow-headed gartersnakes occur
at elevations from approximately 2,300 to 8,000 ft (701 to 2,430 m),
inhabiting Petran Montane Conifer Forest, Great Basin Conifer Woodland,
Interior Chaparral, and the Arizona Upland subdivision of Sonoran
Desertscrub communities (Rosen and Schwalbe 1988, p. 33; Brennan and
Holycross 2006, p. 122).
An extensive evaluation of habitat use of narrow-headed
gartersnakes along Oak Creek in Arizona is provided in Nowak and
Santana-Bendix (2002, pp. 26-37). In the upper reaches of Oak Creek,
occupied habitat is found in a steep-walled, confined canyon with
shallow, braided stream segments, minimal silt, and good canopy
coverage, vegetated islands and significant amounts of aquatic
vegetation (Nowak and Santana-Bendix 2002, pp. 29-30). In the middle
reaches of Oak Creek, occupied habitat is found in a wider canyon with
less stream braiding, deeper pools, more silt, and high canopy coverage
and stream-side vegetation, but less aquatic vegetation (Nowak and
Santana-Bendix 2002, pp. 30-31). In the lower reaches of Oak Creek,
historically occupied habitat occurred outside of the canyon proper,
with predominant pool-run sequences, rare channel braiding, much silt,
significantly less canopy coverage or streamside vegetation and few
areas with aquatic vegetation (Nowak and Santana-Bendix 2002, p. 31).
Nowak and Santana-Bendix (2002, pp. 29-31) found the most narrow-
headed gartersnakes in the upper reaches of Oak Creek, followed by the
middle reaches; no narrow-headed gartersnakes were found in the lower
reaches. Nowak and Santana-Bendix (2002, p. 33) found that, in general,
narrow-headed gartersnakes in Oak Creek were more likely to be found
within reaches without crayfish and without silt. Population densities
of warm-water predatory fish increase on a gradient from the upper to
the lower reaches of Oak Creek, while the inverse is true for native
fish populations, and their presence confounds the analysis of physical
habitat preference of narrow-headed gartersnakes. Rosen and Schwalbe
(1988, p. 35) found that the relative abundance of narrow-headed
gartersnakes may be highest at the conjunction of cascading riffles
with pools, where waters were deeper than 20 in (0.5 m) in the riffle
and deeper than 40 in (1 m) in the immediately adjoining area of the
pool. However, more than twice the number of snakes was found in pools
rather than riffles, but this observation may not translate for smaller
streams. Despite their highly aquatic behavior, narrow-headed
gartersnakes in Oak Creek have been shown to use upland habitat within
328 feet (100 m) during early fall and spring months, strongly
associate with boulders in the floodplain during summer months, and use
upland habitat up to 656 feet (200 m) out of the floodplain as
hibernation sites (Nowak 2006, pp. 20, 26).
Bank-line vegetation is an important component to suitable habitat
for this species (Nowak and Santana-Bendix 2002, pp. 26-37). Narrow-
headed gartersnakes will usually bask in situations where a quick
escape can be made, whether that is into the water or under substrate
such as rocks (Fleharty 1967, p. 16). Common plant species associations
include Arizona alder (Alnus oblongifolia) (highest correlation with
occurrence of the narrow-headed gartersnake), velvet ash (Fraxinus
pennsylvanica), willows (Salix ssp.), canyon grape (Vitis arizonica),
blackberry (Rubus ssp.), Arizona sycamore (Platanus wrightii), Arizona
black walnut (Juglans major), Freemont cottonwood (Populus fremontii),
Gambel oak (Quercus gambelii), and ponderosa pine (Pinus ponderosa)
(Rosen and Schwalbe 1988, pp. 34-35). Rosen and Schwalbe (1988, p. 35)
noted that the composition of bank-side plant species and canopy
structure may be less important to the species' needs than was the size
class of the plant species present; narrow-headed gartersnakes use
shrub- and sapling-sized plants for thermoregulating (basking) at the
waters' edge (Degenhardt et al. 1996, p. 327), as well as islands
within the stream channel that are created by sedge (Carex spp.)
tussocks (Nowak and Santana-Bendix 2002, p. 34).
Narrow-headed gartersnakes may opportunistically forage within
dammed reservoirs formed by streams that are occupied habitat, such as
at Wall Lake, New Mexico, (located at the confluence of Taylor Creek,
Hoyt Creek, and the East Fork Gila River) (Fleharty 1967, p. 207) and
most recently at Snow Lake in 2012 (located near the confluence of Snow
Creek and the Middle Fork Gila River) (Hellekson 2012b, pers. comm.) in
New Mexico, but records from impoundments are rare. The species evolved
in the absence of such habitat, and impoundments are generally managed
as sport fisheries (Wall Lake and Snow Lake are) and often maintain
populations of harmful nonnative species that are incompatible with
narrow-headed gartersnakes.
The narrow-headed gartersnake is surface-active generally between
March and November (Nowak 2006, p. 16). Little information on suitable
temperatures for surface activity of the narrow-headed gartersnake
exists;

[[Page 38685]]

however, it is presumed to be rather cold-tolerant based on its natural
history and foraging behavior that often involves clear, cold streams
at higher elevations. Along Oak Creek in Arizona, Nowak (2006, Appendix
1) found the species to be active in air temperatures ranging from 52
to 89[emsp14][deg]F (11 to 32 [deg]C) and water temperatures ranging
from 54 to 72[emsp14][deg]F (12 to 22 [deg]C). Jennings and Christman
(2011, pp. 12-14) found body temperatures of narrow-headed gartersnakes
along the Tularosa River averaged approximately 68[emsp14][deg]F (20
[deg]C) during the mid-morning hours and 81[emsp14][deg]F (27 [deg]C)
in the late afternoon during the period from late July and August.
Variables that affect their body temperature include the temperature of
the microhabitat used and water temperature (most predictive), but
slope aspect and the surface area of cover used also influenced body
temperatures (Jennings and Christman 2011, p. 13). Narrow-headed
gartersnakes have a lower preferred temperature for activity as
compared to other species of gartersnakes (Fleharty 1967, p. 228),
which may facilitate their highly aquatic nature in cold streams.
Narrow-headed gartersnakes specialize on fish as their primary prey
item (Rosen and Schwalbe 1988, p. 38; Degenhardt et al. 1996, p. 328;
Rossman et al. 1996, p. 247; Nowak and Santana-Bendix 2002, pp. 24-25;
Nowak 2006, p. 22). They are believed to be mainly visual hunters
(Hibbitts and Fitzgerald 2005, p. 364) heavily dependent on visual cues
when foraging based on comparative analyses among other species of
gartersnakes (de Queiroz 2003, p. 381). Unlike many other species of
gartersnakes that are active predators (actively crawl about in search
of prey), narrow-headed gartersnakes are considered to be ambush
predators (sit-and-wait method) (Brennan and Holycross 2006, p. 122;
Pierce et al. 2007, p. 8). The specific gravity (ratio of the mass of a
solid object to the mass of the same volume of water) of the narrow-
headed gartersnake was found to be nearly 1, which means that the snake
can maintain its desired position in the water column with ease, an
adaptation to facilitate foraging on the bottom of streams (Fleharty
1967, pp. 218-219).
Native fish species most often associated as prey items for the
narrow-headed gartersnake include Sonora sucker (Catostomus insignis),
desert sucker (C. clarki), speckled dace (Rhinichthys osculus),
roundtail chub (Gila robusta), Gila chub (Gila intermedia), and
headwater chub (Gila nigra) (Rosen and Schwalbe 1988, p. 39; Degenhardt
et al. 1996, p. 328). Nonnative predatory fish species in their
fingerling size classes are also used as prey by narrow-headed
gartersnakes, including brown trout (Rosen and Schwalbe 1988, p. 39;
Nowak and Santana-Bendix 2002, p. 24; Nowak 2006, pp. 22-23), green
sunfish (Fleharty 1967, p. 223), and smallmouth bass (Micropterus
dolomieu) (M. Lopez, 2010, pers. comm.). Reports suggest that brown
trout are consumed more frequently than smallmouth bass. Trout species
are commonly stocked in, or near, occupied narrow-headed gartersnake
habitat. Fleharty (1967, p. 223) reported narrow-headed gartersnakes
eating green sunfish. But nonnative fish with spiny dorsal fins are not
generally considered suitable prey items due to the risk of injury to
the gartersnake during ingestion and because of where they tend to
occur in the water column (see discussion in the subsection ``Fish''
under the subheading ``Decline of the Gartersnake Prey Base'' and Nowak
and Santana-Bendix (2002, p. 24)).
Although the narrow-headed gartersnake has been reported to also
prey upon amphibians such as frogs, tadpoles, and salamanders (Stebbins
1985, p. 199; Deganhardt et al. 1996, p. 328; Ernst and Ernst 2003, p.
418), we believe these are not important items in their diet. Despite
several studies focusing on the ecology of narrow-headed gartersnakes
in recent times, there are no other records of narrow-headed
gartersnakes, under current taxonomic recognition, feeding on prey
items other than fish. Fitzgerald (1986, p. 6) referenced the Stebbins
(1985) account as the only substantiated account of the species eating
something other than fish as prey, apparently as the result of finding
a small salamander larvae in the stomach of an individual in Durango,
Mexico. Formerly recognized as a subspecies of Thamnophis
rufipunctatus, that individual is now recognized as T. unilabialis
(Wood et al. 2011, p. 3). We found one account of narrow-headed
gartersnakes consuming red-spotted toads in captivity (Woodin 1950, p.
40). Amphibian larvae (i.e. Hyla sp., Anaxyrus sp., Ambystoma sp.) are
generally available to narrow-headed gartersnakes as prey, yet
observations of narrow-headed gartersnakes using them are rare.
Therefore, we do not consider amphibians as ecologically important prey
for this species.
Native predators of the narrow-headed gartersnake include birds of
prey, such as black-hawks (Etzel et al. 2014, p. 56), other snakes such
as regal ring-necked snakes (Brennan et al. 2009, p. 123), wading
birds, mergansers, belted kingfishers, raccoons (Rosen and Schwalbe
1988, p. 39), and possibly other generalist mammalian predators.
Historically, large, highly predatory native fish species, such as
Colorado pikeminnow, may have preyed upon narrow-headed gartersnakes
where the species co-occurred. Native chubs (Gila spp.) may also prey
on neonatal gartersnakes.
Sexual maturity in narrow-headed gartersnakes occurs at 2.5 years
of age in males and at 2 years of age in females (Deganhardt et al.
1996, p. 328). Narrow-headed gartersnakes are viviparous. Narrow-headed
gartersnakes breed annually, and females give birth to 4 to 17
offspring from late July into early August, perhaps earlier at lower
elevations (Rosen and Schwalbe 1988, pp. 35-37). Narrow-headed
gartersnakes may live as long as 10 years in the wild (Rosen and
Schwalbe 1988, p. 38).

Historical Distribution

The historical distribution of the narrow-headed gartersnake ranged
across the Mogollon Rim and along associated perennial stream drainages
from central and eastern Arizona, southeast to southwestern New Mexico
at elevations ranging from 2,300 to 8,000 ft (700 to 2,430 m) (Rosen
and Schwalbe 1988, p. 34; Rossman et al. 1996, p. 242; Holycross et al.
2006, p. 3). The species was historically distributed in headwater
streams of the Gila River subbasin that drain the Mogollon Rim and
White Mountains in Arizona, and the Gila Wilderness in New Mexico.
Major subbasins in its historical distribution included the Salt and
Verde River subbasins in Arizona, and the San Francisco and Gila River
subbasins in New Mexico (Holycross et al. 2006, p. 3). Holycross et al.
(2006, p. 3) suspect the species was likely not historically present in
the lowest reaches of the Salt, Verde, and Gila Rivers, even where
perennial flow persists. Numerous records for the narrow-headed
gartersnake (through 1996) in Arizona are maintained in the AGFD's
Heritage Database (1996b). The narrow-headed gartersnake as currently
recognized does not occur in Mexico.

Current Distribution and Population Status

Population status information suggests that the narrow-headed
gartersnake has experienced significant declines in population density
and distribution along streams and rivers where it was formerly well-
documented and reliably detected. Many areas where the species may
occur likely rely on emigration of individuals from occupied habitat
into those areas to maintain the species, provided there are no
potential

[[Page 38686]]

barriers to movement, such as extensive stretches of dewatered habitat,
or high densities of harmful nonnative species. Holycross et al. (2006,
entire) represents the most recent, comprehensive survey effort for
narrow-headed gartersnakes in Arizona. Narrow-headed gartersnakes were
detected in 5 of 16 historical localities in Arizona and New Mexico
surveyed by Holycross et al. (2006) in 2004 and 2005. Population
densities have noticeably declined in many populations, as compared to
previous survey efforts (Holycross et al. 2006, p. 66). Holycross et
al. (2006, pp. 66-67) compared narrow-headed gartersnake detections
based on results from their effort and that of previous efforts in the
same locations and found that significantly more effort is required to
detect this species in areas where it was formerly robust, such as
along Eagle Creek (AZ), the East Verde River (AZ), the San Francisco
River (NM), the Black River (AZ), and the Blue River (AZ).
Where narrow-headed gartersnakes are locally abundant, they can
usually be detected reliably and with significantly less effort than
populations characterized as having low densities. Narrow-headed
gartersnakes are well-camouflaged, secretive, and very difficult to
detect in structurally complex, dense habitat where they could occur at
very low population densities, which characterizes most occupied sites.
We considered factors such as the date of the last known records for
narrow-headed gartersnakes in an area, as well as records of one or
more native prey species, in making a conclusion on species occupancy.
We used all records that were dated 1980 or later because the 1980s
marked the first systematic survey efforts for narrow-headed
gartersnake species across their range (see Rosen and Schwalbe (1988,
entire) and Fitzgerald (1986, entire)), and the last, previous records
were often dated several decades prior and may not accurately represent
the likelihood for current occupation. Several areas where narrow-
headed gartersnakes were known to occur have received no, or very
little, survey effort in the past several decades. Variability in
survey design and effort makes it difficult to compare population sizes
or trends among sites and between sampling periods. Thus, for each of
the sites discussed in Appendix A (available at http://www.regulations.gov, Docket No. FWS-R2-ES-2013-0071), we have attempted
to translate and quantify search and capture efforts into comparable
units (i.e., person-search hours and trap-hours) and have cautiously
interpreted those results. Where survey data are sparse, the presence
of suitable prey species in an area may provide evidence that narrow-
headed gartersnakes may still persist at low densities. Therefore, a
record of a native prey species was considered in our determination of
occupancy of this species.
As of 2011, the only remaining narrow-headed gartersnake
populations where the species could reliably be found were located at:
(1) Whitewater Creek (NM), (2) Tularosa River (NM), (3) Diamond Creek
(NM), (4) Middle Fork Gila River (NM), and (5) Oak Creek Canyon (AZ).
However, populations found in Whitewater Creek and the Middle Fork Gila
River were likely significantly affected by the large Whitewater-Baldy
Complex Fire, which occurred in June 2012. In addition, salvage efforts
were initiated for these two populations, which included the removal of
25 individuals from Whitewater Creek and 14 individuals from the Middle
Fork Gila River before the onset of summer rains in 2012. These 39
individuals were transported to the Albuquerque BioPark where 22 remain
in captivity. The other 17 of the salvaged individuals were
translocated to Saliz Creek, where the resident native prey base
appears adequate, and beyond the effects from the Whitewater-Baldy
Complex Fire. The status of those populations in Whitewater Creek and
the Middle Fork Gila River has likely deteriorated as a result of
subsequent declines in resident fish communities due to heavy ash and
sediment flows, resulting fish kills, and the removal of snakes, but
subsequent survey data have not been collected. If the Whitewater Creek
and Middle Fork Gila River populations did decline as a result of these
factors, only three remaining populations of this species remain viable
today across their entire distribution. While historical records
confirm the narrow-headed gartersnake was found on tribal lands, its
current status on tribal land is poorly known due to limited survey
access.
In Table 2 below, we summarize the population status of the narrow-
headed gartersnake at all known localities throughout its distribution,
as supported by museum records or reliable observations. For a detailed
discussion that explains the rationale for site-by-site conclusions on
occupancy and status, please see Appendix A (available at http://www.regulations.gov, Docket No. FWS-R2-ES-2013-0071). General rationale
is provided in the introductory paragraph to this section, ``Current
Distribution and Population Status.''

Table 2--Current Population Status of the Narrow-Headed Gartersnake
[References for this information are provided in appendix A]
----------------------------------------------------------------------------------------------------------------
Suitable Harmful
Location Last record physical Native prey nonnative Population
habitat present species present species present status
----------------------------------------------------------------------------------------------------------------
West Fork Gila River (NM)... 2011 Yes............ Yes............ Yes............ Likely not
viable.
Middle Fork Gila River (NM). 2012 Yes............ Yes............ Yes............ Likely not
viable.
East Fork Gila River (NM)... 2006 Yes............ Yes............ Yes............ Likely not
viable.
Gila River (AZ, NM)......... 2009 Yes............ Yes............ Yes............ Likely not
viable.
Snow Creek/Snow Lake (NM)... 2012 Yes............ No............. Yes............ Likely not
viable.
Gilita Creek (NM)........... 2009 Yes............ Yes............ No............. Likely not
viable.
Iron Creek (NM)............. 2009 Yes............ Yes............ No............. Likely not
viable.
Little Creek (NM)........... 2010 Yes............ Possible....... Yes............ Likely not
viable.
Turkey Creek (NM)........... 1985 Yes............ Yes............ Possible....... Likely not
viable.
Beaver Creek (NM)........... 1949 Yes............ Possible....... Yes............ Likely
extirpated.
Black Canyon (NM)........... 2010 Yes............ Yes............ Yes............ Likely not
viable.
Taylor Creek (NM)........... 1960 Yes............ No............. Yes............ Likely
extirpated.
Diamond Creek (NM).......... 2011 Yes............ Yes............ Yes............ Likely viable.
Tularosa River (NM)......... 2012 Yes............ Yes............ Yes............ Likely viable.
Whitewater Creek (NM)....... 2012 Yes............ Yes............ Yes............ Likely not
viable.
San Francisco River (NM).... 2011 Yes............ Yes............ Yes............ Likely not
viable.
South Fork Negrito Creek 2011 Yes............ Possible....... Yes............ Likely not
(NM). viable.
Blue River (AZ)............. 2007 Yes............ Yes............ Yes............ Likely not
viable.

[[Page 38687]]

Dry Blue Creek (AZ, NM)..... 2010 Yes............ Possible....... Yes............ Likely not
viable.
Campbell Blue Creek (AZ, NM) 2010 Yes............ Possible....... Yes............ Likely not
viable.
Saliz Creek (NM)............ 2013 Yes............ Possible....... Yes............ Likely not
viable.
Eagle Creek (AZ)............ 2013 Yes............ Possible....... Yes............ Likely not
viable.
Black River (AZ)............ 2013 Yes............ Yes............ Yes............ Likely not
viable.
East Fork Black River (AZ).. 2004 Yes............ Possible....... Yes............ Likely not
viable.
Fish Creek (Tributary to 2004 Yes............ Yes............ Possible....... Likely viable.
East Fork Black River; AZ).
White River (AZ)............ 1986 Yes............ Yes............ Possible....... Likely not
viable.
Diamond Creek (AZ).......... 1986 Yes............ Possible....... Possible....... Likely not
viable.
Tonto Creek (tributary to 1915 Yes............ Possible....... Possible....... Likely
Big Bonita Creek, AZ). extirpated.
Canyon Creek (AZ)........... 1991 Yes............ Yes............ No............. Likely not
viable.
Upper Salt River (AZ)....... 1985 Yes............ Yes............ Yes............ Likely not
viable.
Cibeque Creek (AZ).......... 1991 Yes............ Yes............ Possible....... Likely not
viable.
Carrizo Creek (AZ).......... 1997 Yes............ Yes............ Possible....... Likely not
viable.
Big Bonito Creek (AZ)....... 1957 Yes............ Yes............ Yes............ Likely
extirpated.
Haigler Creek (AZ).......... 2008 Yes............ Yes............ Yes............ Likely not
viable.
Houston Creek (AZ).......... 2005 Yes............ Yes............ Yes............ Likely not
viable.
Tonto Creek (tributary to 2005 Yes............ Yes............ Yes............ Likely not
Salt River, AZ). viable.
Deer Creek (AZ)............. 1995 No............. No............. No............. Likely
extirpated.
Upper Verde River (AZ)...... 2012 Yes............ Yes............ Yes............ Likely not
viable.
Oak Creek (AZ).............. 2012 Yes............ Yes............ Yes............ Likely viable.
West Fork Oak Creek (AZ).... 2012 Yes............ Yes............ Yes............ Likely viable.
East Verde River (AZ)....... 1992 Yes............ Yes............ Yes............ Likely not
viable.
----------------------------------------------------------------------------------------------------------------
Notes: ``Possible'' means there were no conclusive data found. ``Likely extirpated'' means the last record for
an area pre-dated 1980, and existing threats suggest the species is likely extirpated. ``Likely not viable''
means there is a post-1980 record for the species, it is not reliably found with minimal to moderate survey
effort, and threats exist which suggest the population may be low density or could be extirpated, but there is
insufficient evidence to support extirpation. ``Likely viable'' means that the species is reliably found with
minimal to moderate survey effort, and the population is generally considered to be somewhat resilient.

Table 2 lists the 41 known localities for narrow-headed
gartersnakes throughout their range. We have concluded that, in as many
as 31 of 41 known localities (76 percent), the narrow-headed
gartersnake population is likely not currently viable and may exist at
low population densities that could be threatened with extirpation or
may already be extirpated, but survey data are lacking in areas where
access is restricted. In most localities where the species may occur at
low population densities, existing survey data are insufficient to
conclude extirpation. As of 2014, narrow-headed gartersnake populations
are considered currently likely viable in five localities (12 percent).
The remaining five populations (12 percent) are considered currently
likely extirpated. As displayed in Table 2, harmful nonnative species
are a concern for all but four narrow-headed gartersnake populations.
The status of these populations is expected to continue to decline.

Summary of Biological Status and Threats

Weakened Status of Native Aquatic Communities (Northern Mexican and
Narrow-Headed Gartersnakes) (Factors A, C, and E)

The presence of harmful nonnative species constitutes the most
significant threat to the two gartersnake species. Harmful nonnative
species directly prey upon both species of gartersnake and compete with
them for prey. Harmful nonnative species also compete with gartersnake
prey species as well as modify habitat for both the gartersnakes and
their prey, to the detriment of both gartersnakes. Landscape-level
effects from the continued expansion of harmful nonnative species have
changed the spatial orientation of these gartersnakes' distributions,
creating greater isolation between populations. We expect the viability
of extant gartersnake populations to continue to degrade into the
foreseeable future as a result of ecological interactions with harmful
nonnative species. Riparian and aquatic communities in both the
southwestern United States and Mexico have been significantly impacted
by a shift in species' composition, from one of primarily native fauna,
to one dominated by an expanding assemblage of harmful nonnative animal
species. Harmful nonnative species have been introduced or have spread
into new areas through a variety of mechanisms, including intentional
and accidental releases, sport stocking, aquaculture, aquarium
releases, bait-bucket releases, or natural dispersal (Welcomme 1984,
entire). The ecological ramifications of

[[Page 38688]]

the adversarial relationships within southwestern aquatic communities
have been discussed and described in a broad body of literature,
extending from 1985 to the present (Meffe 1985, pp. 179-185; Propst et
al. 1986, pp. 14-31, 82; 1988, p. 64; 2009, pp. 5-17; Rosen and
Schwalbe 1988, pp. 28, 32; 1997, p. 1; Clarkson and Rorabaugh 1989, pp.
531, 535; Douglas et al. 1994, pp. 9-19; Rosen et al. 1995, pp. 257-
258; 2001, p. 2; Degenhardt et al. 1996, p. 319; Fernandez and Rosen
1996, pp. 8, 23-27, 71, 96; Richter et al. 1997, pp. 1089, 1092; Inman
et al. 1998, p. 17; Rinne et al. 1998, pp. 4-6; Nowak and Santana-
Bendix 2002, Table 3; Propst 2002, pp. 21-25; DFT 2003, pp. 1-3, 5-6,
19; 2004, pp. 1-2, 4-5, 10, Table 1; Bonar et al. 2004, pp. 13, 16-21;
Rinne 2004, pp. 1-2; Clarkson et al. 2005, p. 20; Fagan et al. 2005,
pp. 34, 34-41; Knapp 2005, pp. 273-275; Olden and Poff 2005, pp. 82-87;
Turner 2007, p. 41; Holycross et al. 2006, pp. 13-15; Brennan 2007, pp.
5, 7; Caldwell 2008a, 2008b; d'Orgeix 2008; Luja and Rodr[iacute]guez-
Estrella 2008, pp. 17-22; Propst et al. 2008, pp. 1242-1243; Rorabaugh
2008a, p. 25; Brennan and Rosen 2009, pp. 8-9; Minckley and Marsh 2009,
pp. 50-51; Pilger et al. 2010, pp. 311-312; Stefferud et al. 2009, pp.
206-207; 2011, pp. 11-12; Young and Boyarski 2013, pp. 159-160).

Decline of the Gartersnake Prey Base (Northern Mexican and Narrow-
Headed Gartersnakes) (Factors A and E)

The prey base of these gartersnakes includes native amphibians and
fish populations. Declines in their prey base have led to subsequent
declines in the distribution and density of gartersnake populations. In
most areas across their ranges, prey base declines are largely
attributed to the introduction and expansion of harmful nonnative
species.
Northern Mexican and narrow-headed gartersnakes may be particularly
vulnerable to the loss of native prey species (Rosen and Schwalbe 1988,
pp. 20, 44-45). Rosen et al. (2001, pp. 10, 13, 19) theorized that the
northern Mexican gartersnake: (1) Is unlikely to increase foraging
efforts at the risk of increased predation; and (2) needs adequate food
on a regular basis to maintain its weight and health. If forced to
forage more often for smaller prey items, a reduction in growth and
reproductive rates can result (Rosen et al. 2001, pp. 10, 13). Rosen et
al. (2001, p. 22) hypothesized that the presence and expansion of
nonnative predators (mainly bullfrogs, crayfish, and green sunfish
(Lepomis cyanellus)) are the primary causes of decline in northern
Mexican gartersnakes and in their prey in southeastern Arizona. In
another example, Drummond and Mac[iacute]as Garcia (1989, pp. 25, 30)
found that Mexican gartersnakes fed primarily on frogs, and when frogs
became unavailable, the species simply ceased major foraging
activities. This led the authors to conclude that frog abundance is
probably the most important correlate, and main determinant, of
foraging behavior in northern Mexican gartersnakes.
With respect to narrow-headed gartersnakes, the relationship
between harmful nonnative species, a declining prey base, and
gartersnake populations is clearly depicted in one population along Oak
Creek. Nowak and Santana-Bendix (2002, Table 3) found a strong
correlation in the distribution of fish communities and narrow-headed
gartersnake communities in the vicinity of Midgely Bridge. Downstream
of that point, nonnative, predatory fish species increase in abundance,
and narrow-headed gartersnakes notably decrease in abundance. Upstream
of that point, native fish and nonnative, soft-rayed fish species
increase in abundance as do narrow-headed gartersnakes (Nowak and
Santana-Bendix 2002, p. 23).
Fish (Northern Mexican and Narrow-headed Gartersnakes)--Fish are an
important prey item for the northern Mexican gartersnake and are the
only prey for the narrow-headed gartersnake. Native fish communities
throughout the range of these gartersnake have been on the decline,
both in terms of species composition and biomass, for many decades, and
largely as a result of predation and competition from and with
nonnative, predatory fish species. Stocked for sport, forage, or
biological control, nonnative fishes have been shown to become invasive
where released and do not require the natural flow regimes that native
species do (Kolar et al. 2003, p. 9), which has contributed to their
expansion in the Gila River basin and elsewhere. Northern Mexican and
narrow-headed gartersnakes can successfully use nonnative, soft-rayed
fish species as prey, such as mosquitofish, red shiner, and introduced
trout species, such as rainbow trout (Oncorynchus mykiss), brook trout
(Salvelinus fontinalis), or brown trout (Nowak and Santana-Bendix 2002,
pp. 24-25; Holycross et al. 2006, p. 23). However, predatory fish are
not generally considered prey species for northern Mexican or narrow-
headed gartersnakes and, in addition, are known to prey on neonatal and
juvenile gartersnakes (Young and Boyarski 2013, pp. 158-159). Nowak and
Santana-Bendix (2002, p. 24) propose two hypotheses regarding the
reluctance of narrow-headed gartersnakes to prey on nonnative,
predatory fish: (1) The laterally compressed shape and presence of
sharp, spiny dorsal spines of many nonnative, predatory fish present a
choking hazard to gartersnakes that can be fatal; and (2) nonnative,
predatory fish (with the exception of catfish) tend to occupy the
middle and upper zones in the water column, while narrow-headed
gartersnakes typically hunt along the bottom (where native suckers and
minnows often occur). As a result, nonnative, predatory fish may be
less ecologically available as prey.
Brown trout are highly predatory in all size classes in a wide
range of water temperatures, and they adversely affect native fish
communities wherever they are introduced (Taylor et al. 1984, pp. 343-
344). Predation on gartersnakes by adult brown trout may be a
particular problem for narrow-headed gartersnakes due to their
overlapping distributions and habitat preferences, both in terms of
direct predation on neonatal gartersnakes and through competitive
pressures for gartersnakes by preying on their food source.
Specifically, the younger age classes of brown trout present
competition problems for the narrow-headed gartersnake by eating small
fish. As brown trout mature into the medium to larger size classes,
they may prey upon neonatal narrow-headed gartersnakes. These issues
are confounded by the fact that young brown trout are also eaten by
narrow-headed gartersnakes and may represent an important component of
their prey base, depending on fish species composition and age classes
represented within the resident fish community. However, whatever
benefits fingerling brown trout present for narrow-headed gartersnakes
are likely off-set by effects of brown trout predation on important
native fish species, and possible effects to recruitment of narrow-
headed gartersnakes through predation.
Harmful nonnative species invasions can indirectly affect the
health, maintenance, and reproduction of northern Mexican and narrow-
headed gartersnakes by altering their foraging strategy and
compromising foraging success. Rosen et al. (2001, p. 19), in
addressing the northern Mexican gartersnake, proposed that an increase
in energy expended in foraging, coupled by the reduced number of small
to medium-sized prey fish available, results in deficiencies in
nutrition, affecting growth and reproduction. This occurs because
energy is allocated to maintenance and the increased energy costs of
intense foraging activity, rather than to growth and reproduction. In

[[Page 38689]]

contrast, a northern Mexican gartersnake diet that includes both fish
and amphibians, such as leopard frogs, reduces the necessity to forage
at a higher frequency, allowing metabolic energy gained from larger
prey items to be allocated instead to growth and reproductive
development. Myer and Kowell (1973, p. 225) experimented with food
deprivation in common gartersnakes, and found significant reductions in
lengths and weights of juvenile snakes that were deprived of regular
feedings versus the control group that were fed regularly at natural
frequencies. Reduced foraging success of both northern Mexican and
narrow-headed gartersnakes means that individuals are likely to become
vulnerable to effects from starvation, which may increase fatality
rates of juveniles and, consequently, affect recruitment.
Northern Mexican gartersnakes have a more varied diet than narrow-
headed gartersnakes. We are not aware of any studies that have
addressed the direct relationship between prey base diversity and
northern Mexican gartersnake recruitment and survivorship. However,
Krause and Burghardt (2001, pp. 100-123) discuss the benefits and costs
that may be associated with diet variability in the common gartersnake
(Thamnophis sirtalis), an ecologically similar species to the northern
Mexican gartersnake. Foraging for mixed-prey species may impede
predator learning, as compared to specialization on a certain prey
species, but it may also provide long-term benefits such as the ability
to capture prey throughout their lifespan (Krause and Burghardt 2001,
p. 101).
A wide variety of native fish species (many of which are now listed
as endangered, threatened, or candidates for listing under the Act)
were historically primary prey species for northern Mexican and narrow-
headed gartersnakes (Rosen and Schwalbe 1988, pp. 18, 39). Marsh and
Pacey (2005, p. 60) predict that, despite the significant physical
alteration of aquatic habitat in the southwestern United States, native
fish species could flourish in these altered environments but for the
presence of harmful nonnative fish species. Northern Mexican and, in
particular, narrow-headed gartersnakes depend largely on native fish as
a principal part of their prey base, although nonnative, soft-rayed
predatory fish have also been documented as prey where they overlap in
distribution with these gartersnakes (Nowak and Santana-Bendix 2002,
pp. 24-25; Holycross et al. 2006, p. 23; Emmons and Nowak 2013, p. 6).
Nonnative, predatory fish compete with northern Mexican and narrow-
headed gartersnakes for prey. In their extensive surveys, Rosen and
Schwalbe (1988, p. 44) only found narrow-headed gartersnakes in
abundance where native fish species predominated but did not find them
abundant in the presence of robust nonnative, predatory fish
populations. Minckley and Marsh (2009, pp. 50-51) found nonnative
fishes to be the single-most significant factor in the decline of
native fish species and also their primary obstacle to recovery. Of the
48 conterminous States in the United States, Arizona has the highest
proportion of nonnative fish species (66 percent) represented by
approximately 68 species (Turner and List 2007, p. 13).
Collier et al. (1996, p. 16) note that interactions between native
and nonnative fish have significantly contributed to the decline of
many native fish species from direct predation and, indirectly, from
competition (which has adversely affected the prey base for northern
Mexican and narrow-headed gartersnakes). Holycross et al. (2006, pp.
52-61) documented depressed or extirpated native fish prey bases for
northern Mexican and narrow-headed gartersnakes along the Mogollon Rim
in Arizona and New Mexico. Rosen et al. (2001, Appendix I) documented
the decline of several native fish species in several locations visited
in southeastern Arizona, further affecting the prey base of northern
Mexican gartersnakes in that area.
Harmful nonnative fish species tend to be nest-builders and
actively guard their young, which may provide them another ecological
advantage over native species that are broadcast spawners and provide
no parental care to their offspring (Marsh and Pacey 2005, p. 60). In
fact, nesting smallmouth bass will attack gartersnakes (Winemiller and
Taylor 1982, p. 270). It is, therefore, likely that recruitment and
survivorship is greater in nonnative species than native species where
they overlap, providing nonnative species with an ecological advantage.
Table 2-1 in Kolar et al. (2003, p. 10) provides a map depicting the
high degree of overlap in the distribution of native and nonnative
fishes within the Gila River basin of Arizona and New Mexico as well as
watersheds thought to be dominated by nonnative fish species.
The widespread decline of native fish species from the arid
southwestern United States and Mexico has resulted largely from
interactions with nonnative species and has been noted in the listing
rules of 11 fishes under the Act, and their historical ranges overlap
with the historical distribution of northern Mexican and narrow-headed
gartersnakes. Native fish species that were likely prey species for
these gartersnakes and are now listed under the Act, include the
bonytail chub (Gila elegans, 45 FR 27710, April 23, 1980), Yaqui chub
(Gila purpurea, 49 FR 34490, August 31, 1984), Yaqui topminnow
(Poeciliopsis occidentalis sonoriensis, 32 FR 4001, March 11, 1967),
beautiful shiner (Cyprinella formosa, 49 FR 34490, August 31, 1984),
Gila chub (Gila intermedia, 70 FR 66663, November 2, 2005), Colorado
pikeminnow (Ptychocheilus lucius, 32 FR 4001, March 11, 1967),
spikedace (Meda fulgida, 77 FR 10810, February 23, 2012), loach minnow
(Tiaroga cobitis, 77 FR 10810, February 23, 2012), razorback sucker
(Xyrauchen texanus, 56 FR 54957, October 23, 1991), desert pupfish
(Cyprinodon macularius, 51 FR 10842, March 31, 1986), woundfin
(Plagopterus argentissiums, 35 FR 16047, October 13, 1970), and Gila
topminnow (Poeciliopsis occidentalis, 32 FR 4001, March 11, 1967). In
total within Arizona, 19 of 31 (61 percent) native fish species are
listed under the Act. Arizona ranks the highest of all 50 States in the
percentage of native fish species with declining trends (85.7 percent),
and New Mexico ranks sixth (48.1 percent) (Stein 2002, p. 21; Warren
and Burr 1994, p. 14).
The fastest expanding nonnative species are red shiner (Cyprinella
lutrensis), fathead minnow (Pimephales promelas), green sunfish,
largemouth bass (Micropterus salmoides), western mosquitofish, and
channel catfish (Ictalurus punctatus). A nonnative species can become
invasive if ecological advantages exist for broad physical tolerances,
feeding habits and diet, or reproductive behavior (Taylor et al. 1984,
Table 16-1). These species are considered to be the most invasive in
terms of their negative impacts on native fish communities (Olden and
Poff 2005, p. 75). Many nonnative fishes, in addition to those listed
immediately above, including yellow and black bullheads (Ameiurus sp.),
flathead catfish (Pylodictis olivaris), and smallmouth bass, have been
introduced into formerly and currently occupied northern Mexican or
narrow-headed gartersnake habitat and are predators on these species
(Young and Boyarski 2013, pp. 158-159) and their prey (Bestgen and
Propst 1989, pp. 409-410; Marsh and Minckley 1990, p. 265; Sublette et
al. 1990, pp. 112, 243, 246, 304, 313, 318; Abarca and Weedman 1993,
pp. 6-12; Stefferud and Stefferud 1994, p. 364; Weedman and Young 1997,
pp. 1,

[[Page 38690]]

Appendices B, C; Rinne et al. 1998, pp. 3-6; Voeltz 2002, p. 88; Bonar
et al. 2004, pp. 1-108; Fagan et al. 2005, pp. 34, 38-39, 41; Propst et
al. 2008, pp. 1242-1243). Nonnative, predatory fish species, such as
flathead catfish, may be especially dangerous to narrow-headed
gartersnake populations through competition and direct predation
because they are primarily piscivorous (fish-eating) (Pilger et al.
2010, pp. 311-312), have large mouths, and have a tendency to occur
along the stream bottom, where narrow-headed gartersnakes principally
forage.
Rosen et al. (2001, Appendix I) and Holycross et al. (2006, pp. 15-
51) conducted large-scale surveys for northern Mexican gartersnakes in
southeastern and central Arizona and narrow-headed gartersnakes in
central and east-central Arizona, and documented the presence of
nonnative fish at many locations. Holycross et al. (2006, pp. 14-15)
found nonnative fish species in 64 percent of the sample sites in the
Agua Fria subbasin, 85 percent of the sample sites in the Verde River
subbasin, 75 percent of the sample sites in the Salt River subbasin,
and 56 percent of the sample sites in the Gila River subbasin. In
total, nonnative fish were observed at 41 of the 57 sites surveyed (72
percent) across the Mogollon Rim (Holycross et al. 2006, p. 14).
Entirely native fish communities were presumed in only 8 of 57 sites
surveyed (14 percent) (Holycross et al. 2006, p. 14). It is well
documented that nonnative fish have now infiltrated the majority of
aquatic communities in the southwestern United States as depicted in
Tables 1 and 2, above, as well as in Appendix A (available at http://www.regulations.gov, Docket No. FWS-R2-ES-2013-0071).
Several authors have identified both the presence of nonnative fish
as well as their deleterious effects on native species within Arizona.
Many areas have seen a shift from a predominance of native fishes to a
predominance of nonnative fishes. On the upper Verde River, native
species dominated the total fish community at greater than 80 percent
from 1994 to 1996, before dropping to approximately 20 percent in 1997
and 19 percent in 2001. At the same time, three nonnative species
increased in abundance between 1994 and 2000 (Rinne et al. 2005, pp. 6-
7). In an assessment of the Verde River, Bonar et al. (2004, p. 57)
found that, in the Verde River mainstem, nonnative fishes were
approximately 2.6 times more dense per unit volume of river than native
fishes, and their populations were approximately 2.8 times that of
native fishes per unit volume of river. Similar changes in the
dominance of nonnative fishes have occurred on the Middle Fork Gila
River, with a 65 percent decline of native fishes between 1988 and 2001
(Propst 2002, pp. 21-25). Abarca and Weedman (1993, pp. 6-12) found
that the number of nonnative fish species was twice the number of
native fish species in Tonto Creek in the early 1990s, with a stronger
nonnative species influence in the lower reaches, where the northern
Mexican gartersnake is considered to still occur (Burger 2010, p. 1,
Madera-Yagla 2010, p. 6, 2011, p. 6).
Beginning in 2014, the AGFD plans to stock 4.6 million Florida-
strain largemouth bass, 3.3 million bluegill, and 4.5 million black
crappie annually into Roosevelt Lake in order to control the gizzard
shad (Dorosoma cepedianum) population, which is currently the most
prevalent fish species in the lake and is thought to be depressing
sport fish populations in the reservoir (AGFD 2014, p. 3). Roosevelt
Lake is not, and will never be, suitable habitat for the northern
Mexican gartersnake because of its management as a sport fishery.
However, if the goal of this effort is achieved, we expect a higher
risk of predation of gartersnakes in lower Tonto Creek when a suitable
hydrologic connection is made between Tonto Creek and the lake body
(providing the opportunity for predatory nonnative fish to move into
lower Tonto Creek). We also expect high risk of predation of individual
snakes that may disperse downstream into the lake itself. Fish surveys
in the Salt River above Lake Roosevelt already indicate a decline of
roundtail chub and other native fishes, with an increase in flathead
and channel catfish numbers (Voeltz 2002, p. 49).
In New Mexico, nonnative fish have been identified as the main
cause for declines observed in native fish populations (Voeltz 2002, p.
40; Propst et al. 2008, pp. 1242-1243). Fish experts from the U.S.
Forest Service, U.S. Bureau of Reclamation, U.S. Bureau of Land
Management (BLM), University of Arizona, Arizona State University, The
Nature Conservancy, and others declared the native fish fauna of the
Gila River basin to be critically imperiled, and they cite habitat
destruction and nonnative species as the primary factors for the
declines (DFT 2003, p. 1). They call for the control and removal of
nonnative fish as an overriding need to prevent the decline, and
possible extinction, of native fish species within the basin (DFT 2003,
p. 1). In some areas, nonnative fishes may not dominate the system, but
their abundance has increased. This is the case for the Cliff-Gila
Valley area of the Gila River where nonnative fishes increased from 1.1
percent to 8.5 percent, while native fishes declined steadily over a
40-year period (Propst et al. 1986, pp. 27-32). At the Redrock and
Virden Valleys on the Gila River, the relative abundance in nonnative
fishes in the same time period increased from 2.4 percent to 17.9
percent (Propst et al. 1986, pp. 32-34). Four years later, the relative
abundance of nonnative fishes increased to 54.7 percent at these sites
(Propst et al. 1986, pp. 32-36). The percentage of nonnative fishes
increased by almost 12 percent on the Tularosa River between 1988 and
2003, while on the East Fork Gila River, nonnative fishes increased to
80.5 percent relative abundance in 2003 (Propst 2005, pp. 6-7, 23-24).
In addition to harmful nonnative species, various parasites may
affect native fish species that are prey for northern Mexican and
narrow-headed gartersnakes. Parasites affecting various species of
native fishes within the range of these gartersnakes include Asian
tapeworm (U.S. Fish and Wildlife Service (USFWS) National Wild Fish
Health Survey 2010), Ichthyophthirius multifiliis (Ich) (Mpoame 1982,
p. 46; Robinson et al. 1998, p. 603), anchor worm (Lernaea cyprinacea)
(Robinson et al. 1998, pp. 599, 603-605; Hoffnagle and Cole 1999, p.
24), yellow grub (Clinostomum marginatum) (Amin 1969, p. 436; Mpoame
and Rinne 1983, pp. 400-401; Bryan and Robinson 2000, p. 19; Maine
Department of Inland Fisheries and Wildlife 2002a, p. 1), and black
grub (Neascus spp.), also called black spot (Robinson et al. 1998, p.
603; Bryan and Robinson 2000, p. 21; Lane and Morris 2000, pp. 2-3;
Maine Department of Inland Fisheries and Wildlife 2002b, p. 1; Paroz
2011, pers. comm.). However, currently, we have no information on what
effect parasite infestation in native fish might have on gartersnake
populations.
Decline of Native Fish Communities in Mexico (Northern Mexican
Gartersnake)--The first tabulations of freshwater fish species at risk
in Mexico occurred in 1961, when 11 species were identified as being at
risk (Contreras-Balderas et al. 2003, p. 242). As of 2003, of the 506
species of freshwater fish recorded in Mexico, 185 (37 percent) have
been listed by the Mexican Federal Government as either endangered,
facing extinction, under special protection, or likely extinct
(Alvarez-Torres et al. 2003, p. 323), almost a 17-fold increase in
slightly over four decades; 25 species are believed to have gone
extinct (Contreras-Balderas et al. 2003, p. 241). In the lower
elevations of

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Mexico, within the distribution of the northern Mexican gartersnake,
there are approximately 200 species of native freshwater fish
documented, with 120 native species under some form of threat and an
additional 15 that have gone extinct (Contreras-Balderas and Lozano
1994, pp. 383-384). The Fisheries Law in Mexico empowered the country's
National Fisheries Institute to compile and publish the National
Fisheries Chart in 2000, which found that Mexico's fish fauna has
seriously deteriorated as a result of environmental impacts
(pollution), water basin degradation (dewatering, siltation), and the
introduction of nonnative species (Alvarez-Torres et al. 2003, pp. 320,
323). The National Fisheries Chart is regarded as the first time the
Mexican Government has openly revealed the status of its freshwater
fisheries and described their management policies (Alvarez-Torres et
al. 2003, pp. 323-324).
Industrial, municipal, and agricultural water pollution, dewatering
of aquatic habitat, and the proliferation of nonnative species are
widely considered to be the greatest threats to freshwater ecosystems
in Mexico (Branson et al. 1960, p. 218; Conant 1974, pp. 471, 487-489;
Miller et al. 1989, pp. 25-26, 28-33; 2005, pp. 60-61; DeGregorio 1992,
p. 60; Contreras Balderas and Lozano 1994, pp. 379-381; Lyons et al.
1995, p. 572; 1998, pp. 10-12; Landa et al. 1997, p. 316; Mercado-Silva
et al. 2002, p. 180; Contreras-Balderas et al. 2003, p. 241;
Dom[iacute]nguez-Dom[iacute]nguez et al. 2007, Table 3). A shift in
land use policies in Mexico to encourage free market principles in
rural, small-scale agriculture has been found to promote land use
practices that threaten local biodiversity (Ortega-Huerta and Kral
2007, p. 2; Randall 1996, pp. 218-220; Kiernan 2000, pp. 13-23).
These threats have been documented throughout the distribution of
the northern Mexican gartersnake in Mexico and are best represented in
the scientific literature in the context of fisheries studies.
Contreras-Balderas et al. (2003, pp. 241, 243) named Chihuahua (46
species), Coahuila (35 species), Sonora (19 species), and Durango (18
species) as Mexican states that had some of the most reports of
freshwater fish species at risk. These states are all within the
distribution of the northern Mexican gartersnake, indicating an
overlapping trend of declining prey bases and threatened ecosystems
within the range of the northern Mexican gartersnake in Mexico.
Contreras-Balderas et al. (2003, Appendix 1) found various threats to
be adversely affecting the status of freshwater fish and their habitat
in several states in Mexico: (1) Habitat reduction or alteration
(Sonora, Chihuahua, Durango, Coahuila, San Luis Potos[iacute], Jalisco,
Guanajuato); (2) water depletion (Chihuahua, Durango, Coahuila, Sonora,
Guanajuato, Jalisco, San Luis Potos[iacute]); (3) harmful nonnative
species (Durango, Chihuahua, Coahuila, San Luis Potos[iacute], Sonora,
Veracruz); and (4) pollution (M[eacute]xico, Jalisco, Chihuahua,
Coahuila, Durango). Within the states of Chihuahua, Durango, Coahuila,
Sonora, Jalisco, and Guanajuato water depletion is considered serious,
with entire basins having been dewatered, or conditions have been
characterized as ``highly altered'' (Contreras-Balderas et al. 2003,
Appendix 1). All of the Mexican states with the highest numbers of fish
species at risk are considered arid, a condition hastened by increasing
desertification (Contreras-Balderas et al. 2003, p. 244).
Aquaculture and Nonnative Fish Proliferation in Mexico (Northern
Mexican Gartersnake)--Nonnative fish compete with and prey upon
northern Mexican gartersnakes and their native prey species. The
proliferation of nonnative fish species throughout Mexico happened
mainly by natural dispersal, intentional stockings, and accidental
breaches of artificial or constructed barriers by nonnative fish
(Welcomme 1984, entire). Lentic water bodies such as lakes, reservoirs,
and ponds are often used for flood control, agricultural purposes, and
most commonly to support commercial fisheries. The most recent
estimates indicate that Mexico has 13,936 of such water bodies, where
approximately 96 percent are between 2.47-247 acres (1-100 hectares)
and approximately half are artificial (Sugunan 1997, Table 8.3;
Alvarez-Torres et al. 2003, pp. 318, 322). Areas where these landscape
features are most prevalent occur within the distribution of the
northern Mexican gartersnake. For example, Jalisco and Zacatecas are
listed as two of four states with the highest number of reservoirs, and
Chihuahua is one of two states known for a high concentration of lakes
(Sugunan 1997, Section 8.4.2).
Based on the data presented in Sugunan (1997, Table 8.5), a total
of 422 dammed reservoirs are located within the 16 Mexican states where
the northern Mexican gartersnake is thought to occur. Mercado-Silva et
al. (2006, p. 534) found that, within the state of Guanajuato,
``Practically all streams and rivers in the (Laja) basin are truncated
by reservoirs or other water extraction and storage structures.'' On
the Laja River alone, there are two major reservoirs and a water
diversion dam; 12 more reservoirs are located on its tributaries
(Mercado-Silva et al. 2006, p. 534). As a consequence of dam
operations, the main channel of the Laja remains dry for extensive
periods of time (Mercado-Silva et al. 2006, p. 541). The damming and
modification of the lower Colorado River in Mexico, where the northern
Mexican gartersnake occurred, has facilitated the replacement of the
entire native fishery with nonnative species (Miller et al. 2005, p.
61). Each reservoir created by a dam is either managed as a nonnative
commercial fishery or has become a likely source population of
nonnative species, which have naturally or artificially colonized the
reservoir, dispersed into connected riverine systems, and damaged
native aquatic communities.
Mexico depends in large part on freshwater commercial fisheries as
a source of protein for both urbanized and rural human populated areas.
Commercial and subsistence fisheries rely heavily on introduced,
nonnative species in the largest freshwater lakes (Soto-Galera et al.
1999, p. 133) down to rural, small ponds (Tapia and Zambrano 2003, p.
252). At least 87 percent of the species captured or cultivated in
inland fisheries of Mexico from 1989-1999 included tilapia (Tilapia
spp.), common carp (Cyprinus carpio), channel catfish, trout, and black
bass (Micropterus sp.), all of which are nonnative (Alvarez-Torres et
al. 2003, pp. 318, 322). In fact, the northern and central plateau
region of Mexico (which comprises most of the distribution of the
northern Mexican gartersnake's distribution in Mexico) is considered
ideal for the production of harmful, predatory species such as bass and
catfish (Sugunan 1997, Section 8.3). Largemouth bass are now produced
and stocked in reservoirs and lakes throughout the distribution of the
northern Mexican gartersnake (Sugunan 1997, Section 8.8.1).
The Secretariat for Environment, Natural Resources and Fisheries
(SEMARNAP), formed in 1995, is the Mexican federal agency responsible
for management of the country's environment and natural resources.
SEMARNAP dictates the stocking rates of nonnative species into the
country's lakes and reservoirs. For example, the permitted stocking
rate for largemouth bass in Mexico is one fish per square meter in
large reservoirs (Sugunan 1997, Table 8.8); therefore, a 247-acre (100-
ha) reservoir could be stocked with 1,000,000 largemouth bass. The
common carp, the subject of significant aquaculture investment since
the 1960s in Mexico, is known for altering aquatic habitat and
consuming the eggs and fry of native fish species, and is now

[[Page 38692]]

established in 95 percent of Mexico's freshwater systems (Tapia and
Zambrano 2003, p. 252).
Basins in northern Mexico, such as the Rio Yaqui, have been found
to be significantly compromised by harmful nonnative fish species.
Unmack and Fagan (2004, p. 233) compared historical museum collections
of nonnative fish species from the Gila River basin in Arizona and the
Yaqui River basin in Sonora, Mexico, to gain insight into the trends in
distribution, diversity, and abundance of nonnative fishes in each
basin over time. They found that nonnative species are slowly, but
steadily, increasing in all three parameters in the Yaqui Basin (Unmack
and Fagan 2004, p. 233). Unmack and Fagan (2004, p. 233) predicted
that, in the absence of aggressive management intervention, significant
extirpations or range reductions of native fish species are expected to
occur in the Yaqui Basin of Sonora, Mexico, which may have extant
populations of the northern Mexican gartersnake, as did much of the
Gila Basin before the introduction of nonnative species. Loss of native
fishes impacts prey availability for the northern Mexican gartersnake
and threatens its persistence in these areas. Black bullheads (Ameiurus
melas) were reported as abundant, and common carp were detected from
the Rio Yaqui in southern Sonora, Mexico (Branson et al. 1960, p. 219).
Bluegill (Lepomis macrochirus) were also reported at this location,
representing a significant range expansion that the authors expected
was the result of escaping nearby farm ponds or irrigation ditches
(Branson et al. 1960, p. 220). Largemouth bass, green sunfish, and an
undetermined crappie species have also been reported from this area
(Branson et al. 1960, p. 220).
Documented problems with aquatic habitats in Mexico include water
pollution, harmful nonnative species, and physical habitat alteration.
All of these factors lead to declines in native fish abundance and,
therefore, a decline in the food source for the northern Mexican
gartersnake. Dom[iacute]nguez-Dom[iacute]nguez et al. (2007, p. 171)
sampled 52 localities for a rare freshwater fish, the Picotee goodeid
(Zoogoneticus quitzeoensis), along the southern portion of the Mesa
Central (Mexican Plateau) of Mexico and found 21 localities had
significant signs of pollution. Of the 29 localities where the target
species was detected, 28 of them also had harmful nonnative species
present, such as largemouth bass, cichlids (Oreochromis sp.), bluegill,
and P[aacute]tzcuaro chub (Algansea lacustris) (Dom[iacute]nguez-
Dom[iacute]nguez et al. 2007, pp. 171, Table 3). The first assessment
of the impacts of largemouth bass on native fishes in Mexico was in
1941 during the examination of their effect in Lago de P[aacute]tzcuaro
(Contreras and Escalante 1984, p. 102). Other nonnative fish species
reported are soft-rayed and small bodied, and may be prey items for
younger age classes of gartersnakes.
Several examples of significant aquatic habitat degradation or
destruction were also observed by Dom[iacute]nguez-Dom[iacute]nguez et
al. (2007, Table 3) in this region of Mexico, including the draining of
natural lakes and cienegas for conversion to agricultural purposes,
modification of springs for recreational swimming, diversions, and dam
construction. It should be noted that approximately 17 percent of the
localities sampled by Dom[iacute]nguez-Dom[iacute]nguez et al. (2007,
entire) are within the likely range of the northern Mexican
gartersnake; chiefly sites located within the Rio Grande de Santiago
and Laja Basin. However, collectively, observations made by
Dom[iacute]nguez-Dom[iacute]nguez et al. (2007, entire) provide a
regional context to potential threats acting on northern Mexican
gartersnakes in their southern-most distribution. As of 2006, native
fish species dominated the fish community in both species composition
and overall abundance in the Laja Basin; however, the basin is now
trending toward a nonnative fishery compared to historical data. For
example, nonnative species were most recently collected from 16 of 17
sample sites in the basin, with largemouth bass significantly expanding
their distribution within the headwaters of the basin and bluegill
being widespread in the Laja River (Mercado-Silva et al. 2006, pp. 537,
542, Table 4). The decline of native fishes in this region of Mexico is
likely negatively affecting the status of the northern Mexican
gartersnakes there.
Harmful nonnative fish species in Mexico (Contraras and Escalante
1984, pp. 102-125) may be posing a significant threat to the native
fish prey base of northern Mexican gartersnakes and to the gartersnakes
themselves. The ecological risk of nonnative, freshwater fishes is only
expected to increase with increases in aquaculture production, most
notably in the country's rural, poorest regions (Tapia and Zambrano
2003, p. 252). Amendments to Mexico's existing fishing regulations
imposed by other government regulations have been relaxed, and
investment in commercial fishing has expanded to promote growth in
Mexico's aquaculture sector (Sugunan 1997, Section 8.7.1). Several
areas within the range of the northern Mexican gartersnake in Mexico
have experienced adverse effects associated with nonnative species.
Amphibian Decline (Northern Mexican Gartersnake)--Amphibians are a
principle prey item for the northern Mexican gartersnake, and
documented declines in amphibian population densities and distributions
have significantly contributed to the decline in northern Mexican
gartersnakes. As an example of these effects from another region,
Matthews et al. (2002, p. 16) examined the relationship of gartersnake
distributions, amphibian population declines, and nonnative fish
introductions in high-elevation aquatic ecosystems in California.
Matthews et al. (2002, p. 16) specifically examined the effect of
nonnative trout introductions on populations of amphibians and mountain
gartersnakes (Thamnophis elegans elegans). Their results indicated that
the probability of observing gartersnakes was 30 times greater in lakes
containing amphibians than in lakes where amphibians have been
extirpated by nonnative fish. These results supported a prediction by
Jennings et al. (1992, p. 503) that native amphibian declines will lead
directly to gartersnake declines.
Declines in the native leopard frog populations in Arizona have
likely been a significant, contributing factor to declines in many
northern Mexican gartersnake populations. Native ranid (of the family
Ranidae) frog species, such as lowland leopard frogs, northern leopard
frogs, and federally threatened Chiricahua leopard frogs, have
experienced declines in various degrees throughout their distribution
in the Southwest, largely due to predation and competition with
nonnative species (Clarkson and Rorabaugh 1989, pp. 531, 535; Hayes and
Jennings 1986, p. 490). Rosen et al. (1995, pp. 257-258) found that
Chiricahua leopard frog distribution in the Chiricahua Mountain region
of Arizona was inversely related to nonnative species distribution.
Along the Mogollon Rim, Holycross et al. (2006, p. 13) found that only
8 sites of 57 surveyed (15 percent) consisted of an entirely native
anuran (of the order Anura) community and that native frog populations
in another 19 sites (33 percent) had been completely displaced by
invading bullfrogs. However, such declines in native frog populations
are not necessarily irreversible. Ranid frog populations have been
shown to rebound strongly when nonnative fish are removed (Knapp et al.
2007, pp. 15-18).
Scotia Canyon, in the Huachuca Mountains of southeastern Arizona,
is a location where corresponding declines of leopard frog and northern
Mexican

[[Page 38693]]

gartersnake populations have been documented through repeated survey
efforts over time (Holm and Lowe 1995, p. 33). Surveys of Scotia Canyon
occurred during the early 1980s and again during the early 1990s.
Leopard frogs in Scotia Canyon were infrequently observed during the
early 1980s and were nearly extirpated by the early 1990s (Holm and
Lowe 1995, pp. 45-46). Northern Mexican gartersnakes were observed in
decline during the early 1980s, with low capture rates continuing
through the early 1990s (Holm and Lowe 1995, pp. 27-35). Surveys
documented further decline of leopard frogs and northern Mexican
gartersnakes in 2000 (Rosen et al. 2001, pp. 15-16).
A former large, local population of northern Mexican gartersnakes
at the San Bernardino National Wildlife Refuge (SBNWR) in southeastern
Arizona has also experienced a correlative decline of leopard frogs,
and northern Mexican gartersnakes are now thought to occur at very low
population densities or may be extirpated there (Rosen and Schwalbe
1988, p. 28; 1995, p. 452; 1996, pp. 1-3; 1997, p. 1; 2002b, pp. 223-
227; 2002c, pp. 31, 70; Rosen et al. 1996b, pp. 8-9; 2001, pp. 6-10).
Survey data indicate that declines of leopard frog populations,
often correlated with nonnative species introductions, the spread of a
chytrid fungus (Batrachochytrium dendrobatidis, Bd), and habitat
modification and destruction, have occurred throughout much of the
northern Mexican gartersnake's U.S. distribution (Nickerson and Mays
1970, p. 495; Vitt and Ohmart 1978, p. 44; Ohmart et al. 1988, p. 150;
Rosen and Schwalbe 1988, Appendix I; 1995, p. 452; 1996, pp. 1-3; 1997,
p. 1; 2002b, pp. 232-238; 2002c, pp. 1, 31; Clarkson and Rorabaugh
1989, pp. 531-538; Sredl et al. 1995a, pp. 7-8; 1995b, pp. 8-9, 1995c,
pp. 7-8; 2000, p. 10; Holm and Lowe 1995, pp. 45-46; Rosen et al.
1996b, p. 2; 2001, pp. 2, 22; Degenhardt et al. 1996, p. 319; Fernandez
and Rosen 1996, pp. 6-20; Drost and Nowak 1997, p. 11; Turner et al.
1999, p. 11; Nowak and Spille 2001, p. 32; Holycross et al. 2006, pp.
13-14, 52-61). Holycross et al. (2006, pp. 53-57, 59) documented
population declines and potential extirpations of lowland leopard frogs
(an important prey species of the northern Mexican gartersnake) in most
of the Agua Fria subbasin and areas of the Salt and Verde subbasins in
the period 1986-2006. Specifically, Holycross et al. (2006, pp. 53-57,
59) detected no lowland leopard frogs at several recently,
historically, or potentially occupied locations, including the Agua
Fria River in the vicinity of Table Mesa Road and Little Grand Canyon
Ranch, and at Rock Springs, Dry Creek from Dugas Road to Little Ash
Creek, Little Ash Creek from Brown Spring to Dry Creek, Sycamore Creek
(Agua Fria subbasin) in the vicinity of the Forest Service Cabin, the
Page Springs and Bubbling Ponds fish hatchery along Oak Creek, Sycamore
Creek (Verde River subbasin) in the vicinity of the confluence with the
Verde River north of Clarkdale, along several reaches of the Verde
River mainstem, Cherry Creek on the east side of the Sierra Ancha
Mountains, and Tonto Creek from Gisela to ``the Box,'' near its
confluence with Rye Creek. Rosen et al. (2013, p. 8) suggested that the
decline of leopard frogs in the Empire Valley of southern Arizona is
likely largely responsible for the decline of the northern Mexican
gartersnake there.
A primary factor in the decline of native amphibians as a food
source for northern Mexican gartersnakes in southern Arizona is likely
the result of impacts from nonnative species, mainly bullfrogs. Rosen
et al. (1995, pp. 252-253) sampled aquatic herpetofauna at 103 sites in
the Chiricahua Mountains region, which included the Chiricahua,
Dragoon, and Peloncillo Mountains, and the Sulphur Springs, San
Bernardino, and San Simon valleys. They found that 43 percent of all
ectothermic (cold-blooded) aquatic and semi-aquatic vertebrate species
detected were nonnative. The most commonly encountered nonnative
species was the bullfrog (Rosen et al. 1995, p. 254). Witte et al.
(2008, p. 1) found that the disappearance of ranid frog populations in
Arizona were 2.6 times more likely in the presence of crayfish. Witte
et al. (2008, p. 7) emphasized the significant influence of nonnative
species on the disappearance of ranid frogs in Arizona. In one area,
Rosen et al. (2001, p. 22) identified the expansion of bullfrogs into
the Sonoita grasslands, which contain occupied northern Mexican
gartersnake habitat, and the introduction of crayfish into Lewis
Springs as being of particular concern for the northern Mexican
gartersnake in that area.
In addition to harmful nonnative species, disease and nonnative
parasites have been implicated in the decline of the prey base of the
northern Mexican gartersnake. In particular, the outbreak of
chytridiomycosis or ``Bd,'' a skin fungus, has been identified as a
chief causative agent in the significant declines of many of the native
ranid frogs and other amphibian species. As indicated, Bd has been
implicated in both large-scale declines and local extirpations of many
amphibians, chiefly anuran species, around the world (Johnson 2006, p.
3011). Lips et al. (2006, pp. 3166-3169) suggest that the high
virulence and large number of potential hosts make Bd a serious threat
to amphibian diversity. In Arizona, Bd infections have been reported in
several of the native prey species of the northern Mexican gartersnake
within the distribution of the snake (Morell 1999, pp. 731-732; Sredl
and Caldwell 2000, p. 1; Hale 2001, pp. 32-37; Bradley et al. 2002, p.
207; USFWS 2002, pp. 40802-40804; USFWS 2007a, pp. 26, 29-32). Declines
of native prey species of the northern Mexican gartersnake from Bd
infections have contributed to the decline of this species in the
United States (Morell 1999, pp. 731-732; Sredl and Caldwell 2000, p. 1;
Hale 2001, pp. 32-37; Bradley et al. 2002, p. 207; USFWS 2002, pp.
40802-40804; USFWS 2007a, pp. 26, 29-32).
Evidence of Bd-related amphibian declines has been confirmed in
portions of southern Mexico (just outside the range of northern Mexican
gartersnakes), and data suggest declines are more prevalent at higher
elevations where northern Mexican gartersnakes can occur (Lips et al.
2004, pp. 560-562). However, much less is known about the role of Bd in
amphibian declines across much of Mexico, in particular the mountainous
regions of Mexico (including much of the range of northern Mexican
gartersnakes in Mexico) as the region is significantly understudied
(Young et al. 2000, p. 1218). Because narrow-headed gartersnakes feed
on fish, Bd has not affected their prey base. A recent study in Panama
by Kilburn et al. (2011, p. 132) found that reptiles may act as
reservoirs for Bd (at least in environments such as Panama) based on
the presence of the fungus at non-pathological levels on lizards that
occur in areas with significant Bd outbreaks in resident amphibians.
Their study did not conclude that Bd is a virulent reptile pathogen, or
that it causes disease-induced population declines in reptiles (Kilburn
et al. 2011, p. 132).
Effects of Bullfrogs on Native Aquatic Communities (Northern Mexican
and Narrow-Headed Gartersnakes) (Factors A, C, and E)
Direct predation by, and competition with, bullfrogs is a serious
threat to northern Mexican gartersnakes throughout their range (Conant
1974, pp. 471, 487-489; Rosen and Schwalbe 1988, pp. 28-30; Rosen et
al. 2001, pp. 21-22). Bullfrogs have and do threaten some populations
of narrow-headed

[[Page 38694]]

gartersnakes, but differing habitat preferences between bullfrogs and
narrow-headed gartersnakes lessen their effect on narrow-headed
gartersnake populations. Bullfrogs adversely affect northern Mexican
and narrow-headed gartersnake populations through direct predation of
juveniles and sub-adults. Bullfrogs also compete with northern Mexican
gartersnakes for prey species.
Bullfrogs are not native to the southwestern United States or
Mexico, and they first appeared in Arizona in 1926 as a result of a
systematic introduction effort by the State Game Department (now, the
AGFD) for the purposes of sport hunting and as a food source (Tellman
2002, p. 43). The first bullfrog record from New Mexico is dated 1885
(Degenhardt et al. 1996, p. 85). Bullfrogs are extremely prolific, are
strong colonizers, can reach high densities, are persistent via
cannibalism, and may disperse distances of up to 10 mi (16 km) across
uplands and likely further within drainages (Bautista 2002, p. 131;
Rosen and Schwalbe 2002a, p. 7; Casper and Hendricks 2005, p. 582;
Suhre 2008, pers. comm.; Rosen et al. 2013, pp. 35-36).
Bullfrogs are large-bodied, voracious, opportunistic, even
cannibalistic predators that readily attempt to consume any living
thing smaller than them. Bullfrogs have a highly varied diet, which has
been documented to include vegetation, invertebrates, fish, birds,
mammals, amphibians, and reptiles, including numerous species of snakes
(eight genera, including six different species of gartersnakes, two
species of rattlesnakes, and Sonoran gophersnakes (Pituophis catenifer
affinis)) (Bury and Whelan 1984, p. 5; Clarkson and DeVos 1986, p. 45;
Holm and Lowe 1995, pp. 37-38; Carpenter et al. 2002, p. 130; King et
al. 2002; Hovey and Bergen 2003, pp. 360-361; Casper and Hendricks
2005, pp. 543-544; Combs et al. 2005, p. 439; Wilcox 2005, p. 306;
DaSilva et al. 2007, p. 443; Neils and Bugbee 2007, p. 443; Rowe and
Garcia 2012, pp. 633-634). In one study, three different species of
gartersnakes (Thamnophis sirtalis, T. elegans, and T. ordinoides)
totaling 11 snakes were found inside the stomachs of resident bullfrogs
from a single region (Jancowski and Orchard 2013, p. 26). Bullfrogs can
significantly reduce or eliminate the native amphibian populations
(Moyle 1973, pp. 18-22; Conant 1974, pp. 471, 487-489; Hayes and
Jennings 1986, pp. 491-492; Rosen and Schwalbe 1988, pp. 28-30; 2002b,
pp. 232-238; Rosen et al. 1995, pp. 257-258; 2001, pp. 2, Appendix I;
Wu et al. 2005, p. 668; Pearl et al. 2004, p. 18; Kupferberg 1994, p.
95; Kupferburg 1997, pp. 1736-1751; Lawler et al. 1999; Bury and Whelan
1986, pp. 9-10; Hayes and Jennings 1986, pp. 500-501; Jones and Timmons
2010, pp. 473-474), which are vital for northern Mexican gartersnakes.
Different age classes of bullfrogs can affect native ranid
populations via different mechanisms. Juvenile bullfrogs affect native
ranids through competition; male bullfrogs affect native ranids through
predation; and female bullfrogs affect native ranids through both
mechanisms depending on body size and microhabitat (Wu et al. 2005, p.
668). Pearl et al. (2004, p. 18) also suggested that the effect of
bullfrog introductions on native ranids may be different based on
specific habitat conditions but also suggested that an individual ranid
frog species' physical ability to escape influences the effect of
bullfrogs on each native ranid community. Bullfrogs can also negatively
affect native ranid frog populations, both locally and regionally, as
carriers or reservoir species for Bd, depending on the strain of Bd
(Gervasi et al. 2013, p. 169).
Bullfrogs have been documented to occur throughout Arizona.
Holycross et al. (2006, pp. 13-14, 52-61) found bullfrogs at 55 percent
of sample sites in the Agua Fria subbasin, 62 percent of sites in the
Verde River subbasin, 25 percent of sites in the Salt River subbasin,
and 22 percent of sites in the Gila River subbasin. In total, bullfrogs
were observed at 22 of the 57 sites surveyed (39 percent) across the
Mogollon Rim (Holycross et al. 2006, p. 13). A number of authors have
also documented the presence of bullfrogs throughout many subbasins in
Arizona and New Mexico adjacent to the historical distribution of the
northern Mexican or narrow-headed gartersnake, including northern
Arizona (Sredl et al. 1995a, p. 7; 1995c, p. 7), central Arizona and
along the Mogollon Rim of Arizona and New Mexico (Nickerson and Mays
1970, p. 495; Hulse 1973, p. 278; Sredl et al. 1995b, p. 9; Drost and
Nowak 1997, p. 11; Nowak and Spille 2001, p. 11; Holycross et al. 2006,
pp. 15-51; Wallace et al. 2008; pp. 243-244; Hellekson 2012a, pers.
comm.), southern Arizona (Rosen and Schwalbe 1988, Appendix I; 1995, p.
452; 1996, pp. 1-3; 1997, p. 1; 2002b, pp. 223-227; 2002c, pp. 31, 70;
Holm and Lowe 1995, pp. 27-35; Rosen et al. 1995, p. 254; 1996a, pp.
16-17; 1996b, pp. 8-9; 2001, Appendix I; Turner et al. 1999, p. 11;
Sredl et al. 2000, p. 10; Turner 2007; p. 41), and along the Colorado
River (Vitt and Ohmart 1978, p. 44; Clarkson and DeVos 1986, pp. 42-49;
Ohmart et al. 1988, p. 143). In one of the more conspicuous examples,
bullfrogs were identified as the primary cause for collapse of the
northern Mexican gartersnake and its prey base on the SBNWR (Rosen and
Schwalbe 1988, p. 28; 1995, p. 452; 1996, pp. 1-3; 1997, p. 1; 2002b,
pp. 223-227; 2002c, pp. 31, 70; Rosen et al. 1996b, pp. 8-9).
Once established, bullfrogs are persistent in an area and very
difficult to eradicate. Rosen and Schwalbe (1995, p. 452) experimented
with bullfrog removal at various sites on the SBNWR, in addition to a
control site with no bullfrog removal in similar habitat on the Buenos
Aires National Wildlife Refuge (BANWR). Removal of adult bullfrogs,
without removal of eggs and tadpoles, resulted in a substantial
increase in younger age-class bullfrogs where removal efforts were the
most intensive (Rosen and Schwalbe 1997, p. 6). Contradictory to the
goals of bullfrog eradication, evidence from dissection samples from
young adult and subadult bullfrogs indicated these age-classes readily
prey upon juvenile bullfrogs (up to the average adult leopard frog
size) as well as juvenile gartersnakes, which suggests that the
selective removal of only the large adult bullfrogs (presumed to be the
most dangerous size class to leopard frogs and gartersnakes), favoring
the young adult and sub-adult age classes, could indirectly lead to
increased predation of leopard frogs and juvenile gartersnakes (Rosen
and Schwalbe 1997, p. 6). These findings illustrate that, in addition
to large adults, sub-adult bullfrogs also negatively impact northern
Mexican gartersnakes and their prey species. The findings also indicate
the importance of including egg mass and tadpole removal during efforts
to control bullfrogs and timing removal projects to ensure reproductive
bullfrogs are removed prior to breeding. Recent success in regional
bullfrog eradication has been found in a few cases described below in
the section entitled ``Current Conservation of Northern Mexican and
Narrow-headed Gartersnakes.''
Bullfrogs not only compete with the northern Mexican gartersnake
for prey items but directly prey upon juvenile and, occasionally, sub-
adult northern Mexican and narrow-headed gartersnakes (Rosen and
Schwalbe 1988, pp. 28-31; 1995, p. 452; 2002b, pp. 223-227; Holm and
Lowe 1995, pp. 29-29; Rossman et al. 1996, p. 177; AGFD In Prep., p.
12; 2001, p. 3; Rosen et al. 2001, pp. 10, 21-22; Carpenter et al.
2002, p. 130; Wallace 2002, p. 116). A well-circulated photograph of an
adult bullfrog in the process of consuming a northern Mexican
gartersnake at Parker Canyon Lake, Cochise County, Arizona,

[[Page 38695]]

taken by John Carr of the AGFD in 1964, provides photographic
documentation of bullfrog predation (Rosen and Schwalbe 1988, p. 29;
1995, p. 452). The most recent, physical evidence of bullfrog predation
of northern Mexican gartersnakes is provided in photographs of a
dissected bullfrog at Pasture 9 Tank in the San Rafael Valley of
Arizona that had a freshly eaten neonatal northern Mexican gartersnake
in its stomach (Akins 2012, pers. comm.).
A common observation in northern Mexican gartersnake populations
that co-occur with bullfrogs is a preponderance of large, mature adult
snakes with conspicuously low numbers of individuals in the newborn and
juvenile age size classes. This occurs due to bullfrogs preying on
young small snakes more effectively, which leads to reduced survival of
young and depressed recruitment within populations (Rosen and Schwalbe
1988, p. 18; Holm and Lowe 1995, p. 34). In lotic (flowing water)
systems, bullfrogs prefer sites with low or limited flow, such as
backwaters, side channels, and pool habitat. These areas are also used
frequently by northern Mexican and narrow-headed gartersnakes, which
likely results in increased predation rates and likely depressed
recruitment of gartersnakes. Potential recruitment problems for
northern Mexican gartersnakes due to effects from nonnative species are
suspected at Tonto Creek (Wallace et al. 2008, pp. 243-244). Rosen and
Schwalbe (1988, p. 18) stated that the low recruitment at the SBNWR, a
typical characteristic of gartersnake populations affected by harmful
nonnative species, is the likely cause of that populations' decline and
possibly for declines in populations throughout their range in Arizona.
Specific localities within the distribution of northern Mexican and
narrow-headed gartersnakes where bullfrogs have been detected are
presented in Appendix A (available at http://www.regulations.gov,
Docket No. FWS-R2-ES-2013-0071).
Effects of Crayfish on Native Aquatic Communities (Northern Mexican and
Narrow-Headed Gartersnakes) (Factors A and C)
Crayfish are another nonnative species in Arizona and New Mexico
that threaten northern Mexican and narrow-headed gartersnakes through
competition by consuming prey species of the gartersnakes and through
direct predation on juvenile gartersnakes themselves (Fernandez and
Rosen 1996, p. 25; Voeltz 2002, pp. 87-88; USFWS 2007a, p. 22).
Rogowski et al. (2013, p. 1,280) found Arizona's aquatic communities to
be particularly vulnerable to crayfish because many endemic aquatic
species never evolved in the presence of crayfish. Fernandez and Rosen
(1996, p. 3) studied the effects of crayfish introductions on two
stream communities in Arizona, a low-elevation semi-desert stream and a
high mountain stream, and concluded that crayfish can noticeably reduce
species diversity and destabilize food chains in riparian and aquatic
ecosystems through their effect on vegetative structure, stream
substrate (stream bottom; i.e., silt, sand, cobble, boulder)
composition, and predation on eggs, larval, and adult forms of native
invertebrate and vertebrate species. Crayfish fed on embryos, tadpoles,
newly metamorphosed frogs, and adult leopard frogs, but they did not
feed on egg masses (Fernandez and Rosen 1996, p. 25). However, Gamradt
and Kats (1996, p. 1155) found that crayfish readily consumed the egg
masses of California newts (Taricha torosa). Crayfish are known to also
eat fish eggs and larva (Inman et al. 1998, p. 17), especially those
bound to the substrate (Dorn and Mittlebach 2004, p. 2135). Fernandez
and Rosen (1996, pp. 6-19, 52-56) and Rosen (1987, p. 5) discussed
observations of inverse relationships between crayfish abundance and
native reptile and amphibian populations, including narrow-headed
gartersnakes, northern leopard frogs, and Chiricahua leopard frogs.
Crayfish may also affect native fish populations. Carpenter (2005, pp.
338-340) documented that crayfish may reduce the growth rates of native
fish through competition for food and noted that the significance of
this impact may vary between species.
Crayfish alter the abundance and structure of aquatic vegetation by
grazing on aquatic and semiaquatic vegetation, which reduces the cover
needed by frogs and gartersnakes, as well as the food supply for prey
species such as tadpoles (Fernandez and Rosen 1996, pp. 10-12).
Fernandez and Rosen (1996, pp. 10-12) found that crayfish frequently
burrow into stream banks, leading to increased bank erosion, stream
turbidity, and siltation of stream bottoms. Creed (1994, p. 2098) found
that filamentous alga (Cladophora glomerata) was at least 10-fold
greater in aquatic habitats that lacked crayfish. Filamentous algae is
an important component of aquatic vegetation that provides cover for
foraging gartersnakes, as well as microhabitat for prey species, in
situations where predation risk is high.
Crayfish have recently been found to also act as a host for the
amphibian disease-causing fungus, Bd (McMahon et al. 2013, pp. 210-
213). This could have serious implications for northern Mexican
gartersnakes because crayfish can now be considered a source of disease
in habitat that is devoid of amphibians but otherwise potentially
suitable habitat for immigrating amphibians, such as leopard frogs,
which could serve as a prey base. Because crayfish are so widespread
throughout Arizona, New Mexico, and portions of Mexico, the scope of
this threat is significant for native amphibian populations and,
therefore, to northern Mexican gartersnake populations.
Inman et al. (1998, p. 3) documented crayfish as widely distributed
and locally abundant in a broad array of natural and artificial free-
flowing and still-water habitats throughout Arizona, many of which
overlap the historical and current distribution of northern Mexican and
narrow-headed gartersnakes. Hyatt (undated, p. 71) concluded that the
majority of waters in Arizona contained at least one species of
crayfish. In surveying for northern Mexican and narrow-headed
gartersnakes, Holycross et al. (2006, p. 14) found crayfish in 64
percent of the sample sites in the Agua Fria subbasin; in 85 percent of
the sites in the Verde River subbasin; in 46 percent of the sites in
the Salt River subbasin; and in 67 percent of the sites in the Gila
River subbasin. In total, crayfish were observed at 35 (61 percent) of
the 57 sites surveyed across the Mogollon Rim (Holycross et al. 2006,
p. 14), most of which were sites historically or currently occupied by
northern Mexican or narrow-headed gartersnakes, or sites the
investigators believed possessed suitable habitat and may be occupied
by these gartersnakes based upon their known historical distributions.
A number of authors have documented the presence of crayfish
through their survey efforts throughout Arizona and New Mexico in
specific regional areas, drainages, and lentic wetlands within or
adjacent to the historical distribution of the northern Mexican or
narrow-headed gartersnake, including northern Arizona (Sredl et al.
1995a, p. 7; 1995c, p. 7), central Arizona and along the Mogollon Rim
of Arizona and New Mexico (Sredl et al. 1995b, p. 9; Fernandez and
Rosen 1996, pp. 54-55, 71; Inman et al. 1998, Appendix B; Nowak and
Spille 2001, p. 33; Holycross et al. 2006, pp. 15-51; Brennan 2007, p.
7; Burger 2008, p. 4; Wallace et al. 2008; pp. 243-244; Brennan and
Rosen 2009, p. 9; Karam et al. 2009; pp. 2-3; Hellekson 2012a, pers.
comm.), southern Arizona (Rosen and Schwalbe 1988, Appendix I; Inman et
al. 1998,

[[Page 38696]]

Appendix B; Sredl et al. 2000, p. 10; Rosen et al. 2001, Appendix I),
and along the Colorado River (Ohmart et al. 1988, p. 150; Inman et al.
1998, Appendix B). Specific localities within the distribution of
northern Mexican and narrow-headed gartersnakes where crayfish have
been detected are presented in Appendix A (available at http://www.regulations.gov, Docket No. FWS-R2-ES-2013-0071). Like bullfrogs,
crayfish can be very difficult, if not impossible, to eradicate once
they have become established in an area, depending on the complexity of
the habitat (Rosen and Schwalbe 1996a, pp. 5-8; 2002a, p. 7; Hyatt
undated, pp. 63-71).
It is likely that crayfish populations, where they overlap with
northern Mexican or narrow-headed gartersnakes, could have a varied
influence on gartersnake populations. The size of crayfish can
influence their predatory influence on gartersnakes or their prey
species; small crayfish are unlikely to pose a significant threat to
gartersnakes themselves but may still consume fish eggs or fry, whereas
larger crayfish can prey on neonatal gartersnakes directly. The
presence of adequate numbers of favorable fish prey for narrow-headed
gartersnakes may counter the effects of resident crayfish to some
degree. Crayfish densities may also be affected by periodic flooding,
which is thought to reduce crayfish population densities temporarily
until recolonization occurs from the dispersal of individuals from
downstream populations. More field research is needed to fully
understand the ecological relationship between crayfish and these
gartersnakes, at least at any particular site. However, the best
available scientific and commercial information strongly suggests that
crayfish in larger size classes or in high densities are a cause for
concern for gartersnakes and their prey species, especially with other
threats simultaneously affecting gartersnake populations.
Effects of Predation-Related Injuries to Gartersnakes (Northern Mexican
and Narrow-Headed Gartersnakes) (Factor C)
The tails of gartersnakes are often broken off during predation
attempts by bullfrogs, crayfish, or other predators, and do not
regenerate. The incidence of tail breaks in gartersnakes can often be
used to assess predation pressure within gartersnake populations.
Attempted predation occurs on both sexes and all ages of gartersnakes
within a population, although some general trends have been detected.
For example, female gartersnakes may be more susceptible to predation
as evidenced by the incidence of tail damage (Willis et al. 1982, pp.
100-101; Rosen and Schwalbe 1988, p. 22; Mushinsky and Miller 1993, pp.
662-664; Fitch 2003, p. 212). This can be explained by higher basking
rates associated with pregnant females that increase their visibility
to predators. Fitch (2003, p. 212) found that tail injuries in the
common gartersnake occurred more frequently in adults than in
juveniles. Predation on juvenile snakes likely results in complete
consumption of the animal, which would limit observations of tail
injury in their age class.
Tail injuries can have negative effects on the health, longevity,
and overall success of individual gartersnakes from infection, slower
swimming and crawling speeds, or impeding reproduction. Mushinsky and
Miller (1993, pp. 662-664) commented that, while tail breakage in
gartersnakes can save the life of an individual snake, it also leads to
permanent handicapping of the snake, resulting in slower swimming and
crawling speeds, which could leave the snake more vulnerable to
predation or affect its foraging ability. Willis et al. (1982, p. 98)
discussed the incidence of tail injury in three species in the genus
Thamnophis (common gartersnake, Butler's gartersnake (T. butleri), and
the eastern ribbon snake (T. sauritus)) and concluded that individuals
that suffered nonfatal injuries prior to reaching a length of 12 in (30
cm) are not likely to survive and that physiological stress during
post-injury hibernation may play an important role in subsequent
fatality. While northern Mexican or narrow-headed gartersnakes may
survive an individual predation attempt from a bullfrog or crayfish
with tail damage, secondary effects from infection of the wound may
significantly contribute to fatality of individuals. Perry-Richardson
et al. (1990, p. 77) described the importance of tail-tip alignment in
the successful courtship and mating in Thamnophiine snakes and found
that missing or shortened tails adversely affected these activities
and, therefore, mating success. In researching the role of tail length
in mating success in the red-sided gartersnake (Thamnophis sirtalis
parietalis), Shine et al. (1999, p. 2150) found that males that
experienced injuries or the partial or whole loss of the tail
experienced a three-fold decrease in mating success.
The frequency of tail injuries can be quite high in a given
gartersnake population; for example at the SBNWR (Rosen and Schwalbe
1988, pp. 28-31), 78 percent of northern Mexican gartersnakes had
broken tails with a ``soft and club-like'' terminus, which suggests
repeated injury from multiple predation attempts by bullfrogs. While
medically examining pregnant female northern Mexican gartersnakes,
Rosen and Schwalbe (1988, p. 28) noted bleeding from the posterior
region, which suggested to the investigators the snakes suffered from
``squeeze-type'' injuries inflicted by adult bullfrogs. In another
example, Holm and Lowe (1995, pp. 33-34) observed tail injuries in 89
percent of northern Mexican gartersnakes during the early 1990s in
Scotia Canyon in the Huachuca Mountains, as well as a skewed age class
ratio that favored adults over sub-adults, which is consistent with
data collected by Willis et al. (1982, pp. 100-101) on other
gartersnake species. Bullfrogs are largely thought to be responsible
for the significant decline of northern Mexican gartersnake and its
prey base at this locality, although the latter has improved through
recovery actions. In the Black River, crayfish are very abundant and
have been identified as the likely cause for a high-frequency of tail
injuries to narrow-headed gartersnakes (Brennan 2007, p. 7; Brennan and
Rosen 2009, p. 9). Brennan (2007, p. 5) found that, in the Black River,
14 of 15 narrow-headed gartersnakes captured showed evidence of damaged
or missing tails (Brennan 2007, p. 5). In 2009, 16 of 19 narrow-headed
gartersnakes captured in the Black River showed evidence of damaged or
missing tails (Brennan and Rosen 2009, p. 8). In the middle Verde River
region, Emmons and Nowak (2013, p. 5) reported that 18 of 49 (37
percent) northern Mexican gartersnakes captured had scars (n = 17) and/
or missing tails tips (n = 7).
Vegetation or other forms of protective cover may be particularly
important for gartersnakes to reduce the effects of harmful nonnative
species on populations. For example, the population of northern Mexican
gartersnakes at the Page Springs and Bubbling Ponds State Fish
Hatcheries occurs with harmful nonnative species (Boyarski 2008b, pp.
3-4, 8). Yet, only 11 percent of northern Mexican gartersnakes captured
in 2007 were observed as having some level of tail damage (Boyarski
2008b, pp. 5, 8). The relatively low occurrence of tail damage, as
compared to 78 percent of snakes with tail damage found by Rosen and
Schwalbe (1988, pp. 28-31), may indicate: (1) Adequate vegetation
density was used by gartersnakes to avoid harmful nonnative species
predation attempts; (2) a relatively small population of harmful
nonnative species may be at a comparatively lower density than sites
sampled by previous studies

[[Page 38697]]

(harmful nonnative species population density data were not collected
by Boyarski (2008b)); (3) gartersnakes may not have needed to move
significant distances at this locality to achieve foraging success,
which might reduce the potential for encounters with harmful nonnative
species; or (4) gartersnakes infrequently escaped predation attempts by
harmful nonnative species, were removed from the population, and were
consequently not detected by surveys.
Expansion of the American Bullfrog and Crayfish in Mexico (Northern
Mexican Gartersnake) (Factors A, C, and E)
Bullfrogs are a significant threat to native aquatic and riparian
species throughout Mexico. Luja and Rodr[iacute]guez-Estrella (2008,
pp. 17-22) examined the invasion of the bullfrog in Mexico. The
earliest records of bullfrogs in Mexico were Nuevo Leon (1853),
Tamaulipas (1898), Morelos (1968), and Sinaloa (1969) (Luja and
Rodr[iacute]guez-Estrella 2008, p 20). By 1976, the bullfrog was
documented in seven more states: Aguacalientes, Baja California Sur,
Chihuahua, Distrito Federal, Puebla, San Luis Potosi, and Sonora (Luja
and Rodr[iacute]guez-Estrella 2008, p. 20). The bullfrog was recently
verified from the state of Hidalgo, Mexico, at an elevation of 8,970
feet (2,734 m), which indicates the species continues to spread in that
country and can exist even at the uppermost elevations inhabited by
northern Mexican gartersnakes (Duifhuis Rivera et al. 2008, p. 479). As
of 2008, Luja and Rodr[iacute]guez-Estrella (2008, p. 20) have recorded
bullfrogs in 20 of the 31 Mexican States (65 percent of the states in
Mexico) and suspect that they have invaded other States, but were
unable to find documentation.
Bullfrogs have been commercially produced for food in Mexico in
Yucatan, Nayarit, Morelos, Estado de Mexico, Michoac[aacute]n,
Guadalajara, San Luis Potosi, Tamaulipas, and Sonora, and their use for
food was endorsed by the Mexican Secretary of Aquaculture Support (Luja
and Rodr[iacute]guez-Estrella 2008, p. 20). However, frog legs
ultimately never gained popularity in Mexican culinary culture (Conant
1974, pp. 487-489), and Luja and Rodr[iacute]guez-Estrella (2008, p.
22) point out that only 10 percent of these farms remain in production.
Luja and Rodr[iacute]guez-Estrella (2008, pp. 20, 22) document
instances where bullfrogs have escaped production farms and suspect the
majority of the frogs that were produced commercially in farms that
have since ceased operation have assimilated into surrounding habitat.
Luja and Rodr[iacute]guez-Estrella (2008, p. 20) also state that
Mexican people deliberately introduce bullfrogs for ornamental
purposes, or ``for the simple pleasure of having them in ponds.'' The
act of deliberately releasing bullfrogs into the wild in Mexico was
cited by Luja and Rodr[iacute]guez-Estrella (2008, p. 21) as being
``more common than we can imagine.'' Bullfrogs are available for
purchase at some Mexican pet stores (Luja and Rodr[iacute]guez-Estrella
2008, p. 22). Luja and Rodr[iacute]guez-Estrella (2008, p. 21) state
that bullfrog eradication efforts in Mexico are often thwarted by their
popularity in rural communities (presumably as a food source).
Currently, no regulation exists in Mexico to address the threat of
bullfrog invasions or prevent their release into the wild (Luja and
Rodr[iacute]guez-Estrella 2008, p. 22). As a result, the bullfrogs'
distribution continues to increase in Mexico, beyond what it would
through natural dispersal mechanisms.
Rosen and Melendez (2006, p. 54) report bullfrog invasions to be
prevalent in northwestern Chihuahua and northwestern Sonora, where the
northern Mexican gartersnake is thought to occur. In many areas, native
leopard frogs were completely displaced where bullfrogs were observed.
Rosen and Melendez (2006, p. 54) also demonstrated the relationship
between fish and amphibian communities in Sonora and western Chihuahua.
Native leopard frogs, a primary prey item for the northern Mexican
gartersnake, only occurred in the absence of nonnative fish, and were
absent from waters containing nonnative species, which included several
major waters. In Sonora, Rorabaugh (2008a, p. 25) also considers the
bullfrog to be a significant threat to the northern Mexican gartersnake
and its prey base, substantiated by field observations made during
surveys conducted in Chihuahua and Sonora in 2006 (Rorabaugh 2008b, p.
1).
Few data were found on the presence or distribution of nonnative
crayfish species in Mexico. However, in a 2-week gartersnake survey
effort in 2006 in northern Mexico, crayfish were observed as ``widely
distributed'' in the valleys of western Chihuahua (Rorabaugh 2008b, p.
1). Based on the invasive nature of crayfish ecology and their
distribution in the United States along the Border region, it is
reasonable to assume that, at a minimum, crayfish are likely
distributed along the entire Border region of northern Mexico, adjacent
to where they occur in the United States, and act in a similar fashion
on affected northern Mexican gartersnake populations.
Risks to Gartersnakes From Fisheries Management Activities (Northern
Mexican and Narrow-Headed Gartersnakes) (Factors A and E)
The decline in native fish communities from the effects of harmful
nonnative fish species has spurred resource managers to take action to
help recover native fish species. While we fully support activities
designed to help recover native fish, recovery actions for native fish,
in the absence of thorough planning, can have negative effects on
resident gartersnake populations.
Piscicides--Piscicide is a term that refers to a ``fish poison.''
The use of piscicides, such as rotenone or antimycin A, for the removal
of harmful nonnative fish species has widely been considered invaluable
for the conservation and recovery of imperiled native fish species
throughout the United States, and in particular the Gila River basin of
Arizona and New Mexico (Dawson and Kolar 2003, entire). Antimycin A is
rarely used anymore due to limited production and has been largely
replaced by rotenone in field applications. Experimentation with
ammonia as a piscicide has shown promising results and may ultimately
replace rotenone in the future as a desired control method if legally
registered for such use (Ward et al. 2013, pp. 402-404). Currently,
rotenone is the most commonly used piscicide. The active ingredient in
rotenone is a natural chemical compound extracted from the stems and
roots of tropical plants in the family Leguminosae that interrupts
oxygen absorption in gill-breathing animals (Fontenot et al. 1994, pp.
150-151). In the greater Gila River subbasin alone, 57 streams or water
bodies have been treated with piscicide, some on several occasions
spanning many years (Carpenter and Terrell 2005; Table 6). However,
this practice has been the source of recent controversy due to a
perceived link between rotenone and Parkinson's disease in humans, as
well as potential effects to livestock.
Speculation of the potential role of rotenone in Parkinson's
disease was fueled by Tanner et al. (2011, entire), which correlated
the incidence of the disease with lifetime exposure to certain
pesticides, including rotenone. As a result, in 2012, the Arizona State
Legislature proposed two bills that called for the development of an
environmental impact statement prior to the application of rotenone or
antimycin A (S.B. 1453, see State of Arizona Senate (2012b)) and urged
the U.S. Environmental Protection Agency to deregister rotenone from
use in the

[[Page 38698]]

United States (S.B. 1009, see State of Arizona Senate (2012b)). Public
safety considerations were fully evaluated by a multidisciplined
technical team of specialists that found no correlation between
rotenone applications performed, according to product label
instructions, and Parkinson's disease (Rotenone Review Advisory
Committee 2012, pp. 24-25). Nonetheless, continued anxiety regarding
the use of piscicides for conservation and management of fish
communities leaves an uncertain future for this important management
tool. Should circumstances result in the discontinued practice of using
piscicides for fish recovery and management, the likelihood of recovery
for listed or sensitive aquatic vertebrates in Arizona, such as
northern Mexican and narrow-headed gartersnakes, would be substantially
reduced, if not eliminated outright.
The use of piscicides is a vital and scientifically sound tool, the
only tool, in most circumstances, for reestablishing native fish
communities and removing threats related to nonnative aquatic species
in occupied northern Mexican and narrow-headed gartersnake habitat. By
extension, the use of piscicides is also invaluable in the recovery and
conservation of northern Mexican and narrow-headed gartersnakes.
However, without proper planning the amount of time a treated water
body remains fishless post-treatment can affect gartersnakes by
removing fish, their primary food source. The time period between
rotenone applications and the subsequent restocking of native fish is
contingent on two basic variables, the time it takes for piscicide
levels to reach nontoxic levels and the level of certainty required to
ensure that renovation goals and objectives have been met prior to
restocking. Implementation of the latter consideration may vary from to
a year or longer, depending on the level of certainty required by
project proponents. Carpenter and Terrell (2005, p. 14) reported that
standard protocols used by the AGFD for Apache trout renovations at
that time required two applications of piscicide before repatriating
native fish to a stream, waiting a season to see if the renovation was
successful, and then continuing to renovate if necessary. Past
protocols have included goals for the renovated water body to remain
fishless for extended periods, sometimes up to an entire year before
restocking (Carpenter and Terrell 2005, p. 14). At a minimum and
according to our files, reaches of Big Bonito Creek, the West Fork
Black River, West Fork Gila River, Little Creek, and O'Donnell Creek
have all been subject to fish renovations using these or similarly
accepted protocols (Carpenter and Terrell 2005; Table 6; Paroz and
Propst 2009, p. 4; Hellekson 2012a, pers. comm.). Therefore, northern
Mexican or narrow-headed gartersnake populations in these streams have
likely been negatively affected, due to the eradication of a portion
of, or their entire, prey base in these systems for varying periods of
time. Big Bonito Creek was restocked with salvaged native fish shortly
after renovation occurred. However, we are uncertain how long other
stream reaches remained fishless post-treatment, but it was likely to
be a minimum of weeks in each instance, and possibly a year or longer
in some instances.
Although significant efforts are generally made to salvage as many
native fish as possible prior to treatment, logistics of holding fish
for several weeks prior to restocking limit the number of individuals
that can be held safely. Therefore, not every individual fish is
salvaged, and native fish remaining in the stream are subsequently lost
during the treatment. The number of fish subsequently restocked is,
therefore, smaller than the number of fish that were present prior to
the treatment. The full restoration of native fish populations to pre-
treatment levels may take several years, depending on the size of the
treated area and the size and maturity of the founding populations.
Restocking salvaged fish in the fall may allow natural spawning and
recruitment to begin in the spring, which would provide a more
immediate benefit to resident gartersnake populations.
Several streams within the distribution of narrow-headed
gartersnakes in New Mexico have been identified for potential future
fish barrier construction, for which piscicide applications are likely
necessary. These streams include Little Creek, West Fork Gila River,
Middle Fork Gila River, Turkey Creek, Saliz Creek, Dry Blue Creek, Iron
Creek, and the San Francisco River (Riley and Clarkson 2005, pp. 4-5,
7, 9, 12; Clarkson and Marsh 2012, p. 8; 2013, pp. 1, 4, 6; Hellekson
2013, pers. comm.). Of these, the Middle Fork Gila River and Turkey
Creek appear to the most likely chosen for renovation (Clarkson and
Marsh 2013, p. 8). Mule Creek and Cienega Creek, both occupied by
northern Mexican gartersnakes, as well as Whitewater Creek (occupied by
narrow-headed gartersnakes), are under consideration but ultimately may
not be chosen (Clarkson and Marsh 2013, pp. 8-9). Haigler Creek
(occupied by narrow-headed gartersnakes) is planned for renovation in
2015 (Burger and Jeager 2013, p. 2) and barrier development.
The current standard operating procedures for piscicide
application, as adopted nationally and provided in Finlayson et al.
(2010, p. 23), provide guidance for assuring that nontarget, baseline
environmental conditions (the biotic community) are accounted for in
assessing whether mitigation measures are necessary. This procedural
protocol states, ``Survival and recovery of the aquatic community may
be demonstrated by sampling plankton, macroinvertebrates (aquatic
insects, crustacea, leeches, and mollusks), and amphibians (frogs,
tadpoles, and larval and adult salamanders)'' (Finlayson et al. 2010,
p. 23). This protocol, adopted by the AGFD (see AGFD 2012a), does not
in itself consider the effects of leaving a treated water body without
a prey base for a sensitive species much less for a fish-specialist,
such as the narrow-headed gartersnake, for extended periods of time.
However, the AGFDs' internal Environmental Assessment Checklist (EAC)
addresses considerations for nontarget aquatic reptiles. Thus, we
believe that concerns for potential effects of piscicide treatments on
these gartersnake species within Arizona should not be substantial in
the future.
As of 2012, a new policy was finalized by the AGFD that includes an
early and widespread public notification and planning process that
involves the approval of several decision-makers within four major
stages: (1) Piscicide project internal review and approval; (2)
preliminary planning and public involvement; (3) intermediate planning
and public involvement; and (4) project implementation and evaluation
(AGFD 2012a, p. 3). Within the Internal Review and Approval stage of
the process, sensitive, endemic, and listed species potentially
impacted by the project must be identified (AGFD 2012a, p. 13), such as
northern Mexican or narrow-headed gartersnakes. This change ensures
that an analysis of potential effects to nontarget wildlife by
fisheries management activities occurs within the same planning
document, versus a separate process. In addition, the AGFD's
Conservation and Mitigation Program has specifically committed to
quickly restocking renovated streams that are occupied by either
northern Mexican or narrow-headed gartersnakes (USFWS 2011, Appendix
C).
Piscicide application protocols used by the New Mexico Department
of Game and Fish are provided in Pierce (2014,

[[Page 38699]]

entire) and specify that effects to amphibian species are reviewed
prior to application; however, the protocol does not provide for an
assessment of potential gartersnake effects from treatment. No specific
timeframe, post-treatment, was recommended by the protocol for when
native fish are recommended for stocking into treated waters (Pierce
2014, pers. comm.). We intend to coordinate with the New Mexico
Department of Game and Fish as active partners in wildlife conservation
to ensure potential effects, from piscicide treatments, to either
gartersnake are avoided or minimized. However, if proper protocols are
not incorporated into future fish restoration projects, these
activities will continue to threaten local gartersnake populations.
Mechanical Methods--In addition to chemical renovation techniques,
mechanical methods using electroshocking equipment are often used in
fisheries management, both for nonnative aquatic species removal and
fisheries survey and monitoring activities that often occur in
conjunction with piscicide treatments. Northern Mexican and narrow-
headed gartersnakes often flee into the water as a first line of
defense when startled. In occupied habitat, gartersnakes present in the
water and within the affected radius of electroshockers are often
temporarily paralyzed from electrical impulses intended for fish, and
are, therefore, readily detected by surveyors (Hellekson 2012a, pers.
comm.). We are not aware of any research that has investigated
potential short- or long-term consequences to gartersnakes from these
events, and so we do not consider electroshock surveys as a substantial
threat to either gartersnake.
Trapping methods are also used in fisheries surveys, for other
applications in aquatic species management, and for the collection of
live baitfish in recreational fishing. One such common method to study
aquatic or semi-aquatic wildlife (including populations of aquatic
snakes such as gartersnakes) is through the use of wire minnow traps.
When used to monitor gartersnake populations, wire minnow traps are
anchored to vegetation, logs, etc., along the shoreline (in most
applications) and positioned so that half to one-third of the trap,
along its lateral line, is above the water surface to allow snakes to
surface for air. These traps often attract prey species, such as small
fishes and amphibian larvae (when present), and, therefore, become
self-baiting. They are then checked according to a predetermined
schedule. Because the wire, twine, etc., used to anchor these traps is
fixed in length, these traps may become fully submerged if there is a
sudden, unanticipated rise in water levels (e.g., storm event). During
the monsoon in Arizona and New Mexico, these types of storm events are
common, and river hydrographs respond accordingly with rapid and
dynamic increases in flow.
We are aware of examples where northern Mexican gartersnakes,
intentionally captured in minnow traps, have drowned as a direct result
of a rapid, unexpected rise in water levels. Some examples include an
adult female northern Mexican gartersnake along lower Tonto Creek in
2004, an adult and two neonates at the Bubbling Ponds State Fish
Hatchery in 2009 and 2010, respectively, and an individual of
undisclosed age in the upper Santa Cruz River (Holycross et al. 2006,
p. 41, Boyarski 2011, pp. 2-3; Lashway 2012, p. 5). In another example,
involving an underwater funnel trap used to survey for lowland leopard
frogs (but which are not used for fishery surveys), a large adult
female northern Mexican gartersnake was discovered deceased in the trap
(Jones 2012a, pers. comm.). Death of that individual was likely due to
drowning or predation by numerous crayfish that were also confined in
the funnel trap with the gartersnake (Jones 2012a, pers. comm.).
Depending on the mesh size of traps, neonatal gartersnakes can become
stuck in the mesh of traps (Lashway 2012, p. 5), which could result in
injury or death of the individual. There are likely additional cases
where northern Mexican or narrow-headed gartersnake fatality from
trapping has not been reported, particularly where trapping has
occurred in occupied habitat prone to flash flooding.
Minnow traps are often deployed for monitoring fully aquatic
species, such as fish, and are, therefore, intentionally positioned in
the water column where they are fully under water. Traps used for this
purpose may be checked less frequently, because risks to gill-breathing
aquatic species are less if held in the trap for longer periods of
time. As fish collectively become trapped, the trap becomes
incidentally self-baited for gartersnakes and, if deployed in habitat
occupied by either northern Mexican or narrow-headed gartersnakes,
these traps may accidentally attract, capture, and drown gartersnakes
that are actively foraging under water and are lured to the traps
because of captured prey species. Neonatal northern Mexican and narrow-
headed gartersnakes can also wriggle through the mesh of some wire
minnow traps and become lodged halfway through, depending on the pore
size of the wire mesh (Jaeger 2012, pers. comm.). If not found in time,
this situation would likely result in their death from drowning,
predation, or exposure.
The use of minnow traps is also allowed in recreational fishing in
Arizona and New Mexico (AGFD 2013a, p. 57; New Mexico Department of
Game and Fish (NMDGF) 2013, p. 17). In Arizona and New Mexico, it is
lawful to set minnow traps for the collection of live baitfish (AGFD
2013a, pp. 56-57; NMDGF 2013, p. 17). In Arizona, minnow traps used for
collecting live baitfish must be checked once daily and the trapping
activity must occur where captured bait will be used (AGFD 2013a, pp.
56-57); in New Mexico, there is no stipulation on time intervals in the
regulations to check minnow traps (NMDGF 2013, p. 17). In either
scenario in either state, these minnow traps are likely to be fully
submerged when in use and pose a drowning hazard to resident
gartersnakes while foraging underwater, as they can be lured into the
traps by fish already caught.
We do not have adequate information to assess the frequency and
geographical extent to which accidental drownings of gartersnakes in
minnow traps may be occurring. This is mainly because it happens
incidentally as a result of trapping efforts for other species, and so
it historically did not get reported by researchers. Without additional
information, we cannot conclude at this time that deaths from
accidental minnow trapping are likely having population-level effects
on either gartersnake. However, if even a few adult females are lost
from populations that already have low densities and low rates of
recruitment, these losses would contribute to population extirpations
and the continued decline in the status of the gartersnakes. Working
with researchers in the future to minimize the chances of snake
drownings and to report any incidental collections of gartersnakes will
be important for future conservation of both species.
Intentional Dewatering--Lastly, dewatering or water fluctuation
techniques are sometimes considered for eliminating undesirable fish
species from water bodies (Finlayson et al. 2010, p. 4). Dewatering of
occupied northern Mexican or narrow-headed gartersnake habitat would
have deleterious effects to affected populations by removing a primary
habitat feature and eliminating the prey base. Because northern Mexican
gartersnakes often occupy lentic water bodies or intermittently watered
canyon bottoms, where this practice is most feasible, effects of
dewatering activities may disproportionately affect that

[[Page 38700]]

species. This technique is being considered by the AGFD for pools
within Redrock Canyon where northern Mexican gartersnakes could be
adversely affected. We have been made aware that northern Mexican
gartersnakes are being considered by the AGFD in their implementation
planning process. Depending on the availability of suitable habitat
regionally and the length of time water is absent, these activities may
ultimately cause local extirpations of gartersnake populations.
Summary
In our review of the scientific and commercial literature, we have
found that over time, native aquatic communities, specifically the
native prey bases for northern Mexican and narrow-headed gartersnakes,
have been substantially weakened as a result of the cumulative effects
of disease and harmful nonnative species. Harmful nonnative species
have been intentionally introduced or have naturally dispersed into
virtually every subbasin throughout the distribution of northern
Mexican and narrow-headed gartersnakes in the United States and Mexico.
According to Geographic Information System (GIS) analyses, nonnative,
predatory fish are known to occur in 90 percent of the historical
distribution of the northern Mexican gartersnake and 85 percent of the
historical distribution of the narrow-headed gartersnake in the United
States. Bullfrogs are known to occur in 85 percent of the historical
distribution of the northern Mexican gartersnake and 53 percent of the
historical distribution of the narrow-headed gartersnake in the United
States. Crayfish are known to occur in 77 percent of the historical
distribution of the northern Mexican gartersnake and 75 percent of the
historical distribution of the narrow-headed gartersnake in the United
States. Nonnative, predatory fish, bullfrogs, and crayfish are known to
occur simultaneously in 65 percent of the historical distribution of
the northern Mexican gartersnake and 44 percent of the historical
distribution of the narrow-headed gartersnake in the United States.
Native fish are important prey for northern Mexican gartersnakes
but much more so for narrow-headed gartersnakes. Predation by and
competition with primarily nonnative, predatory fish species, and
secondarily with brown trout and crayfish, are widely considered to be
the primary reason for major declines in native fish communities
throughout the range of both gartersnakes. In Arizona, 19 of 31 (61
percent) of all native fish species are listed under the Act.
Consequently, Arizona ranks the highest of all 50 States in the
percentage of native fish species with declining trends (85.7 percent).
Similar trends in the loss of native fish biodiversity have been
described in New Mexico and Mexico. Native amphibians such as the
Chiricahua leopard frog, an important component of the northern Mexican
gartersnake prey base, have declined significantly and may face future
declines as a result of Bd and harmful nonnative species. Historical
native frog populations have been wholly replaced by harmful nonnative
species, both on local and regional scales. These declines have
directly contributed to subsequent northern Mexican gartersnake
population declines or extirpations in these areas. An adequate native
prey base is essential to the conservation and recovery of northern
Mexican gartersnakes, and this native ranid frog prey base faces an
uncertain future if harmful nonnative species continue to persist and
expand their distributions in occupied habitat.
The best available commercial and scientific information confirms
that harmful nonnative species are the most important threat to
northern Mexican and narrow-headed gartersnakes and their prey bases,
and they have had a profound role in their decline. A large body of
literature documents that northern Mexican and narrow-headed
gartersnakes are uniquely susceptible to the influence of harmful
nonnative species in their biotic communities. This sensitivity is
largely the result of complex ecological interactions that result in
direct predation on gartersnakes; shifts in biotic community structure
from largely native to largely nonnative; and competition for a
diminished prey base that can ultimately result in the injury,
starvation, or death of northern Mexican or narrow-headed gartersnakes
followed by reduced recruitment, population declines, and extirpations.
Lastly, fisheries management activities can have negative effects
on gartersnake populations when gartersnakes are not considered in
project planning and implementation. The use of rotenone and other
fisheries management techniques are important in the conservation and
recovery of native fish. However, significant threats can occur if
streams are left without an intact fish community for extended periods
of time. New policies and mitigation measures have been developed in
Arizona that will reduce the likelihood of these activities having
negative effects on either northern Mexican or narrow-headed
gartersnake populations in the future. However, some level of effect is
still expected based on logistical complications and complexities of
restoring fish populations to pre-treatment levels. We expect to
coordinate with resource managers in New Mexico as we do in Arizona, to
ensure gartersnake populations are not significantly affected by these
activities. However, if proper protocols are not incorporated into
future fish restoration projects, these activities will continue to
threaten local gartersnake populations. Other mechanisms or activities
used in fisheries management, such as electroshocking, trapping, or
dewatering, can result in the injury or death of northern Mexican or
narrow-headed gartersnakes, where these activities coincide with extant
populations, and if they have not been considered in the planning or
implementation processes. The significance of these losses depends on
the status of the gartersnake population affected and whether or not
either gartersnake, as appropriate, was considered in project planning.
If similar fisheries management techniques are used in Mexico, we
conclude that the northern Mexican gartersnake populations in Mexico
are threatened by the same mechanisms described above.
The presence of harmful nonnative species ultimately affects where
northern Mexican and narrow-headed gartersnakes can live as viable
populations. Collectively, the ubiquitous presence of harmful nonnative
species across the landscape has appreciably reduced the quantity of
suitable gartersnake habitat and changed its spatial orientation on the
landscape. Most northern Mexican and narrow-headed gartersnake
populations, even some considered viable today, live in the presence of
harmful nonnative species. While they continue to persist, they do so
under constant threat from unnatural levels of predation and
competition associated with harmful nonnative species. This weakens
their resistance to other threats, including those that affect the
physical suitability of their habitat (discussed below). This
ultimately renders populations much less resilient to stochastic,
natural, or anthropogenic stressors that could otherwise be withstood.
Over time and space, subsequent population declines have threatened the
genetic representation of each species because many populations have
become disconnected and isolated from neighboring populations.
Expanding distances between extant populations coupled with increasing
populations of

[[Page 38701]]

harmful nonnative species prevents normal colonizing mechanisms that
would otherwise reestablish populations where they have become
extirpated. This subsequently leads to a reduction in species
redundancy when isolated, small populations are at increased
vulnerability to the effects of stochastic events, without a means for
natural recolonization. Ultimately, the effect of scattered, small, and
disjunct populations, without the means to naturally recolonize, is
weakened species resiliency as a whole, which ultimately enhances the
risk of either or both species becoming endangered.
Therefore, based on the best available scientific and commercial
information, we conclude that harmful nonnative species are the most
significant threat to both the northern Mexican and narrow-headed
gartersnake, rangewide. We expect the impacts from harmful nonnative
species to only increase in the foreseeable future. The effects of
these threats on both gartersnakes have resulted in the extirpation of
a few populations already and the decline in abundance in the vast
majority of populations, so we expect the results of continuing decline
of the gartersnakes, in terms of additional population losses and
increased risk of extinction in the foreseeable future, which we
consider as the next several decades.

Main Factors That Destroy or Modify the Physical Habitat of Northern
Mexican and Narrow-Headed Gartersnakes (Factor A)

Relationship Between Harmful Nonnative Species and Adverse Effects to
Physical Habitat (Northern Mexican and Narrow-headed Gartersnakes)
The presence or absence of harmful nonnative species in occupied
gartersnake habitat affects the tolerance, or sensitivity, of
gartersnake populations to factors or activities that threaten to
modify or destroy components of their physical habitat. When we use the
term ``physical habitat,'' we refer to the structural integrity of
aquatic and terrestrial components to habitat, such as plant species
richness and density, available water, stream banks and substrates, and
any habitat feature that does not pertain to the animal community,
which we also define as a habitat component. The animal community (the
prey and predator species that co-occur within habitat) is not
considered in our usage of ``physical habitat,'' for reasons described
immediately below. In the presence of harmful nonnative species,
gartersnake populations are more sensitive to alterations in their
physical habitat. In the absence of harmful nonnative species,
gartersnake populations have shown resiliency, or tolerance, to changes
in their physical habitat.
As discussed above, we found harmful nonnative species to be a
significant and widespread factor that continues to drive further
declines in and extirpations of gartersnake populations. Furthermore,
we found various activities have affected, and continue to affect,
primary components of the physical habitat required by northern Mexican
and narrow-headed gartersnakes, even when the potential impact of
harmful nonnatives is absent. These activities, such as dams, water
diversions, groundwater pumping, and residential and commercial
development, result in the loss of stream flow. The period from 1850 to
1940 marked the greatest loss and degradation of riparian and aquatic
communities in Arizona, many of which were caused by anthropogenic
(human-caused) land uses (Stromberg et al. 1996, p. 114; Webb and Leake
2005, pp. 305-310). An estimated one-third of Arizona's wetlands has
dried or is no longer suitable (Yuhas 1996, entire). However, not all
aquatic and riparian habitats in the United States that support
northern Mexican or narrow-headed gartersnakes have been degraded or
lost. Despite the loss or modification of aquatic and riparian habitat,
large reaches of the Verde, Salt, San Pedro, and Gila Rivers, as well
as several of their tributaries, remain functionally suitable as
physical habitat for either gartersnake species.
Our treatment of how the loss or modification of physical habitat
may affect the northern Mexican or narrow-headed gartersnake is based,
in part, on recent observations made in Mexico that illustrate the
relationship of gartersnakes' physical habitat suitability to the
presence of native prey species and the lack of harmful nonnative
species, and the presence, or lack thereof, of attributes associated
with these gartersnakes' physical habitat. In 2007, two groups
consisting of agency biologists (including U.S. Fish and Wildlife
Service staff), species experts, and field technicians conducted
numerous gartersnake surveys in Durango and Chihuahua, Mexico (Burger
2007, p. 1; Burger et al. 2010, entire).
While considerable gartersnake habitat in Mexico is affected by the
presence of harmful nonnative species (Conant 1974, pp. 471, 487-489;
Contreras Balderas and Lozano 1994, pp. 383-384; Unmack and Fagan 2004,
p. 233; Miller et al. 2005, pp. 60-61; Rosen and Melendez 2006, p. 54;
Luja and Rodr[iacute]guez-Estrella 2008, pp. 17-22), Burger (2007, pp.
1-72) surveyed several sites in remote areas that appeared to be free
of nonnative species. In some sites, the physical habitat for northern
Mexican gartersnakes and similar species of gartersnakes appeared to be
in largely good condition, but few or no gartersnakes were detected. At
other sites, the physical habitat was drastically affected by
overgrazing, rural development, or road crossings; however,
gartersnakes were relatively easily detected, indicating seemingly
adequate population densities, but we do not have the necessary data to
calculate population trends at sampled localities. Inversely,
gartersnake habitat in Arizona and New Mexico is in relatively better
physical condition compared to observations of these habitats made in
Durango and Chihuahua, Mexico. However, harmful nonnative species are
essentially ubiquitous in the southwestern United States, based on our
literature review and GIS modeling. Several sites visited by Burger
(2007, pp. 1-72) in Durango and Chihuahua, Mexico, had physical habitat
in poor to very poor condition, but were largely free of nonnative
species. These situations are rarely encountered in Arizona and New
Mexico and, therefore, provided Burger (2007, entire) a unique
opportunity to examine differences in gartersnake population densities
based on condition of the physical habitat, without the confounding
effect of harmful nonnative species on resident gartersnake
populations.
Our observations of gartersnake populations in Mexico provide
evidence for the relative importance of native prey species and the
lack of nonnative species in comparison to the physical attributes of
gartersnake habitat. For example, Burger (2007, pp. 6, 12, 36, 41, 58,
63) detected moderate to high densities of gartersnakes at six sites
where their physical habitat was moderately to highly impacted by land
uses but were largely free of nonnatives. Burger (2007, pp. 18, 26, 32,
61, 64, 66, 67, 69, 72) also detected either low densities or no
gartersnakes at nine sites where the physical habitat was in moderate
to good condition but where nonnative species were detected. Eight
streams surveyed by Burger (2007, pp. 15, 22, 46, 49, 51-52, 54, 62)
had little to no surface flow, were without fish detections and had few
to no gartersnake observations. As a result, we have formulated three
general hypotheses: (1) Northern Mexican and narrow-headed gartersnakes
may be

[[Page 38702]]

more resilient to adverse effects to physical habitat in the absence of
harmful nonnative species and, therefore, more sensitive to negative
effects to physical habitat in the presence of harmful nonnative
species; (2) the presence of an adequate prey base is important for
persistence of gartersnake populations regardless of whether or not
harmful nonnative species are present; and (3) detections and effects
from harmful nonnative species appear to decrease from north to south
in the Mexican states of Chihuahua and Durango (from the United States-
Mexico International Border), as discussed in Unmack and Fagan (2004,
pp. 233-243).
Based on field data collected by Burger (2007, entire), Burger et
al. (2010, entire), and on the above hypotheses, we evaluated effects
to physical habitat in the context of the presence or absence of
nonnative species. Effects to the physical habitat of gartersnakes can
have varying effects on the gartersnakes themselves depending on the
composition of their biotic community. In the presence of harmful
nonnative species, effects to physical habitat, especially those that
diminish or weaken the gartersnake prey base, are believed to be
comparatively more significant than those that do not. As previously
discussed, harmful nonnative species are essentially ubiquitous in
Arizona and New Mexico where the northern Mexican and narrow-headed
gartersnakes occur and, therefore, exacerbate the effects from
activities or factors that modify or destroy their physical habitat.
Altering or Dewatering Aquatic Habitat (Northern Mexican and Narrow-
headed Gartersnakes)
Dams and Diversions (Northern Mexican and Narrow-headed
Gartersnakes)--The presence of water is critical for northern Mexican
and narrow-headed gartersnakes, as well as their prey base. Activities
that reduce flows or dewater habitat, such as dams, diversions, flood-
control projects, and groundwater pumping, seriously threaten the
physical habitat of the gartersnakes, because both fish and amphibians
must have water to survive and reproduce and without this prey base,
gartersnakes cannot persist. Such activities are widespread in Arizona.
For example, municipal water use in central Arizona increased by 39
percent from 1998 to 2006 (American Rivers 2006), and at least 35
percent of Arizona's perennial rivers have been dewatered, assisted by
approximately 95 dams that are in operation in Arizona today (Turner
and List 2007, pp. 3, 9). Larger dams may prevent movement of fish
between populations (which affects prey availability for northern
Mexican and narrow-headed gartersnakes) and dramatically alter the flow
regime of streams through the impoundment of water (Ligon et al. 1995,
pp. 184-189). These diversions also require periodic maintenance and
reconstruction, resulting in potential habitat damages and inputs of
sediment into the active stream.
Flow regimes within stream systems are a primary factor that shape
fish community assemblages. The timing, duration, intensity, and
frequency of flood events has been altered to varying degrees by the
presence of dams, which has an effect on fish communities (Rinne et al.
1998, pp. 8-10; 2005, p. 2). Specifically, Haney et al. (2008, p. 61)
suggested that flood pulses may help to reduce populations of nonnative
species, and efforts to increase the baseflows may assist in sustaining
native prey species for northern Mexican and narrow-headed
gartersnakes. However, the investigators in this study also suggest
that, because the northern Mexican gartersnake preys on both fish and
frogs, it may be less affected by reductions in baseflow of streams
(Haney et al. 2008, pp. 82, 93). The effect of regulated flow regimes
on the fish community in the Bill Williams River was studied by Pool
and Olden (2014 In press, p. 5), who found the presence of Alamo Dam
having a negative effect on native fish, while benefitting harmful
nonnative species, which now account for the majority of the fish
fauna, in terms of species composition and relative biomass, in the
Bill Williams River.
Other streams that are not dammed in the same watershed still
reflect a largely native fish community due to the presence of a
natural flow regime (Pool and Olden 2014 In press, pp. 5-6). Collier et
al. (1996, p. 16) mentions that water development projects are one of
two main causes for the decline of native fish in the Salt and Gila
rivers of Arizona. Unregulated flows with elevated discharge events
favor native species, and regulated flows, absent significant discharge
events, favor nonnative species (Propst et al. 2008, p. 1246).
Interactions among native fish, nonnative fish, and flow regimes were
observed in the upper reaches of the East Fork of the Gila River. Prior
to the 1983 and 1984 floods in the Gila River system, native fish
occurrence was limited, while nonnative fish were moderately common.
Following the 1983 flood event, adult nonnative predators were
generally absent, and native fish were subsequently collected in
moderate numbers in 1985 (Propst et al. 1986, p. 83). These
relationships are most readily observed in canyon-bound streams, where
shelter sought by nonnative species during large-scale floods is
minimal (Propst et al. 2008, p. 1249). Propst et al. (2008, p. 1246)
also suggested the effect of nonnative fish species on native fish
communities may be most significant during periods of natural drought
(simulated by artificial dewatering).
Effects from flood control projects threaten riparian and aquatic
habitat, as well as threaten the northern Mexican gartersnake directly
in lower Tonto Creek. Kimmell (2008, pers. comm.), Gila County Board of
Supervisors (2008, pers. comm.), Trammell (2008, pers. comm.), and
Sanchez (2008, pers. comm.) all discuss a growing concern of residents
that live within or adjacent to the floodplain of Tonto Creek in Gila
County, Arizona, both upstream and downstream of the town of Gisela,
Arizona. Specifically, there is growing concern to address threats to
private property and associated infrastructure posed by flooding of
Tonto Creek (Sanchez 2008, pers. comm.). An important remaining
population of northern Mexican gartersnakes within the Salt River
subbasin occurs on Tonto Creek. In Resolution No. 08-06-02, the Gila
County Board of Supervisors proactively declared a state of emergency
within Gila County as a result of the expectation for heavy rain and
snowfall causing repetitive flooding conditions (Gila County Board of
Supervisors 2008, pers. comm.). In response, the Arizona Division of
Emergency Management called meetings and initiated discussions among
stakeholders in an attempt to mitigate these flooding concerns (Kimmell
2008, pers. comm., Trammell 2008, pers. comm.).
Mitigation measures that have been discussed include removal of
riparian vegetation, removal of debris piles, potential channelization
of Tonto Creek, improvements to existing flood control structures or
addition of new structures, and the construction of new bridges.
Adverse effects from these types of activities to aquatic and riparian
habitat, and to the northern Mexican gartersnake or its prey species,
will result from the physical alteration or destruction of habitat,
significant increases to flow velocity, and removal of key foraging
habitat and areas to hibernate, such as debris jams. Specifically,
flood control projects permanently alter stream flow characteristics
and have the potential to make the stream unsuitable as habitat for the
northern Mexican gartersnake by reducing or eliminating stream
sinuosity

[[Page 38703]]

and associated pool and backwater habitats that are critical to
northern Mexican gartersnakes and their prey species. Threats presented
by these flood control planning efforts are considered imminent within
the next decade because high flows associated with the monsoon are
expected to increase in both intensity and frequency according to
climate change predictions, as discussed below in the section ``Climate
Change and Drought.''
Many streams in New Mexico, currently or formerly occupied by
northern Mexican or narrow-headed gartersnakes, have been or could be
affected by water withdrawals. Approximately 9.5 river mi (15.3 km) of
the Gila River mainstem in New Mexico, from Little Creek to the Gila
Bird Area, are in private ownership and have been channelized, and the
water is largely used for agricultural purposes (Hellekson 2012a, pers.
comm.). Below the Highway 180 crossing of the mainstem Gila River,
several water diversions have reduced stream flow (Hellekson 2012a,
pers. comm.). Channelization has also affected a privately owned reach
of Whitewater Creek from the Catwalk downstream to Glenwood, New Mexico
(Hellekson 2012a, pers. comm.). The Gila River downstream of the town
of Cliff, New Mexico, flows through a broad valley where irrigated
agriculture and livestock grazing are the predominant uses. Human
settlement has increased since 1988 (Propst et al. 2008, pp. 1237-
1238). Agricultural practices have led to dewatering of the river in
the Cliff-Gila valley at times during the dry season (Soles 2003, p.
71). For those portions of the Gila River downstream of the Arizona-New
Mexico border, agricultural diversions and groundwater pumping have
caused declines in the water table, and surface flows in the central
portion of the river basin are diverted for agriculture (Leopold 1997,
pp. 63-64; Tellman et al. 1997, pp. 101-104).
The San Francisco River in New Mexico has undergone sedimentation,
riparian habitat degradation, and extensive water diversion, and at
present has an undependable water supply throughout portions of its
length (Hellekson 2012a, pers. comm.; 2013, pers. comm.). The San
Francisco River is seasonally dry in the Alma Valley, and two diversion
structures fragment habitat in the upper Alma Valley and at Pleasanton
(NMDGF 2006, p. 302). An approximate 2-stream-mi (3.2-km) reach of the
lower San Francisco River between the Glenwood Diversion and Alma
Bridge, which would otherwise be good narrow-headed gartersnake
habitat, has been completely dewatered by upstream diversions
(Hellekson 2012a, pers. comm.).
Additional withdrawals of water from the Gila and San Francisco
Rivers may occur in the next several decades as the effects of drought
and human population levels increase. Implementation of Title II of the
Arizona Water Settlements Act (AWSA) (Public Law 108-451) would
facilitate the exchange of Central Arizona Project water within and
between southwestern river basins in Arizona and New Mexico, and may
result in the construction of new water development projects. Section
212 of the AWSA pertains to the New Mexico Unit of the Central Arizona
Project. The AWSA provides for New Mexico water users to deplete 14,000
acre-feet of additional water from the Gila Basin in any 10-year
period. The settlement also provides the ability to divert that water
without complaint from downstream pre-1968 water rights in Arizona. New
Mexico will receive $66 million to $128 million in non-reimbursable
Federal funding. The Interstate Stream Commission (ISC) funds may be
used to cover costs of an actual water supply project, planning,
environmental mitigation, or restoration activities associated with or
necessary for the project, and may be used on one or more of 15
alternative projects ranging from Gila National Forest San Francisco
River Diversion/Ditch improvements to a regional water supply project
(the Deming Diversion Project). Currently, 3 of the 15 projects under
consideration include elements of diversion or storage. At this time,
it is not known how the funds will be spent or which potential
alternatives may be chosen. While multiple potential project proposals
have been accepted by the New Mexico Office of the State Engineer
(NMOSE) (NMOSE 2011a, p. 1), implementation of the AWSA is still in the
planning stages on these streams, and final notice is expected by the
end of 2014. Should water be diverted from the Gila or San Francisco
Rivers, flows would be diminished and direct and indirect losses and
degradation of habitat for the narrow-headed gartersnake and its prey
species would result.
In addition to affecting the natural behavior of streams and rivers
through changes in timing, intensity, and duration of flood events,
dams create reservoirs that alter resident fish communities (Paradzick
et al. 2006, entire). Water level fluctuation can affect the degree of
benefit to harmful nonnative fish species. Reservoirs that experience
limited or slow fluctuations in water levels are especially beneficial
to harmful nonnative species whereas reservoirs that experience greater
fluctuations in water levels provide less benefit for harmful nonnative
species (Paradzick et al. 2006, entire). The timing of fluctuating
water levels contributes to their effect; a precipitous drop in water
levels during harmful nonnative fish reproduction is most deleterious
to their recruitment (Paradzick et al. 2006, entire). A drop in water
levels outside of the reproductive season of harmful nonnative species
has less effect on overall population dynamics (Paradzick et al. 2006,
entire). Large dams can also act as fish barriers, which prevent
upstream migration of harmful nonnative fish that occur downstream of
these structures.
The cross-sectional profile of any given reservoir also contributes
to its benefit for harmful nonnative fish species (Paradzick et al.
2006, entire). Shallow reservoir profiles generally provide maximum
space and elevated water temperatures favorable to reproduction of
harmful nonnative species, while deep reservoir profiles, with limited
shallow areas, provide commensurately less benefit (Paradzick et al.
2006, entire). Examples of reservoirs that benefit harmful nonnative
species, and therefore adversely affect northern Mexican and narrow-
headed gartersnakes (presently or historically), include Horseshoe and
Bartlett Reservoirs on the Verde River, and Roosevelt, Saguaro, Canyon,
and Apache Lakes on the Salt River. The Salt River Project (SRP)
operates the previously mentioned reservoirs on the Verde and Salt
Rivers and, in the case of Horseshoe and Bartlett Reservoirs, received
section 10(a)(1)(B) take authorization under the Act for adverse
effects to several avian and aquatic species (including northern
Mexican and narrow-headed gartersnakes) through a comprehensive threat
minimization and mitigation program found in SRP's habitat conservation
plan (SRP 2008, entire). There is no such minimization and mitigation
program developed for the operation of Lake Roosevelt, where
comparatively limited fluctuation in reservoir levels benefit harmful
nonnative species and negatively affect northern Mexican or narrow-
headed gartersnakes and their prey bases in Tonto Creek. A detailed
analysis of the effects of reservoir operations on aquatic communities
is provided in our intra-Service biological and conference opinion
provided in USFWS (2008, pp. 112-131).
The Effect of Human Population Growth and Development on Water
Demands and Gartersnake Habitat (Northern Mexican and Narrow-headed

[[Page 38704]]

Gartersnakes)--Arizona's population is expected to double from 5
million to 10 million people by the year 2030, which will put
increasing pressure on water demands (Overpeck 2008, entire). Arizona
increased its population by 474 percent from 1960 to 2006 (Gammage
2008, p. 15) and is second only to Nevada as the fastest growing State
in terms of human population (Social Science Data Analysis Network
(SSDAR) (2000, p. 1). Over approximately the same time period,
population growth rates in Arizona counties where northern Mexican or
narrow-headed gartersnake habitat exists have varied by county but are
no less remarkable, and all are increasing: Maricopa (463 percent);
Pima (318 percent); Santa Cruz (355 percent); Cochise (214 percent);
Yavapai (579 percent); Gila (199 percent); Graham (238 percent); Apache
(228 percent); Navajo (257 percent); Yuma (346 percent); LaPaz (142
percent); and Mohave (2,004 percent) (SSDAR 2000, entire). From 1960 to
2006, the Phoenix metropolitan area alone grew by 608 percent, and the
Tucson metropolitan area grew by 356 percent (Gammage 2008, p. 15).
Population growth in Arizona is expected to be focused along wide
swaths of land from the international border in Nogales, through
Tucson, Phoenix, and north into Yavapai County (called the Sun Corridor
``Megapolitan'') and is predicted to have 8 million people by 2030, an
82.5 percent increase from 2000 (Gammage et al. 2008, pp. 15, 22-23).
If build-out occurs as expected, it could indirectly affect (through
increased recreation pressure and demand for water) currently occupied
habitat for the northern Mexican or narrow-headed gartersnake,
particularly regional populations in lower Cienega Creek near Vail,
Arizona, and the Verde Valley, and, to a lesser extent, Red Rock Canyon
in extreme south-central Arizona.
The effect of the increased water withdrawals may be exacerbated by
the current, long-term drought facing the arid southwestern United
States, which is predicted to continue. The effect of long-term drought
has already been observed in the Southwest. Philips and Thomas (2005,
pp. 1-4) provided stream flow records that indicate that the drought
Arizona experienced between 1999 and 2004 was the worst drought since
the early 1940s and possibly earlier. The Arizona Drought Preparedness
Plan Monitoring Technical Committee (ADPPMTC) (2012) determined the
drought status within the Arizona distributions of northern Mexican and
narrow-headed gartersnakes, through June 2012, to be in ``severe
drought.'' Ongoing drought conditions have depleted recharge of
aquifers and decreased base flows in the region. While drought periods
have been relatively numerous in the arid Southwest from the mid-1800s
to the present, the effects of human-caused impacts on riparian and
aquatic communities have compromised the ability of these communities
to function under the additional stress of prolonged drought
conditions. Below we further discuss the effect of climate change-
induced drought in the future.
The Arizona Department of Water Resources (ADWR) manages water
supplies in Arizona and has established five Active Management Areas
(AMAs) across the State (ADWR 2006, entire). An AMA is established by
ADWR when an area's water demand has exceeded the groundwater supply
and an overdraft has occurred. In these areas, groundwater use has
exceeded the rate where precipitation can recharge the aquifer, and
these areas are subject to regulation pursuant to Arizona's Groundwater
Code with a goal of balancing groundwater use with recharge (reaching
safe yield) by the year 2025. Geographically, these five AMAs overlap
the historical distribution of the northern Mexican or narrow-headed
gartersnake, or both, in Arizona. The establishment of these AMAs
further illustrates the condition of limited water availability for
riparian habitat in these areas both currently and into the future, and
they indicate a cause of concern for the long-term maintenance of
northern Mexican and narrow-headed gartersnake habitat. These areas are
already vulnerable to declines in surface and groundwater availability,
and surface water may not be sustainable to support the gartersnakes'
prey base. An overdraft of groundwater withdrawal creates what is
referred to as a cone of depression within the groundwater. Reduced or
eliminated surface flow can result in areas where these cones of
depression intersect with stream alluvium (deposits in a valley a
stream flows through).
The presence of surface water is a primary habitat component for
northern Mexican and narrow-headed gartersnakes. Existing water laws in
Arizona and New Mexico may not be fully adequate to protect gartersnake
habitat from the dewatering effects of groundwater withdrawals. New
Mexico water law now includes provisions for instream water rights to
protect fish and wildlife and their habitats. Arizona water law also
recognizes such provisions; however, because this change is relatively
recent, instream water rights have low priority, and are often never
fulfilled because more senior diversion rights have priority. Existing
water laws are considered outdated and reflect a legislative
interpretation of water resources that is not consistent with current
scientific understanding of the hydrologic connection between
groundwater and surface water (Gelt 2008, pp. 1-12).
Water for development and urbanization is often supplied by
groundwater pumping and surface water diversions from sources that
include reservoirs and Central Arizona Project's allocations from the
Colorado River. As stated previously, groundwater pumping creates a
cone of depression within the affected aquifer that slowly radiates
outward from the well site. When the cone of depression intersects the
hyporheic zone of a stream (the active transition zone between two
adjacent ecological communities under or beside a stream channel or
floodplain between the surface water and groundwater that contributes
water to the stream itself), the surface water flow may decrease, and
the subsequent drying of riparian and wetland vegetative communities
can follow. Continued groundwater pumping at such levels draws down the
aquifer sufficiently to create a water-level gradient away from the
stream and floodplain (Webb and Leake 2005, p. 309). Complete
disconnection of the aquifer and the stream results in strong negative
effects to riparian vegetation (Webb and Leake 2005, p. 309) that
result in a reduction or loss in surface water and riparian vegetation
that can reduce or eliminate the local prey base that gartersnakes
depend on for survival.
The arid southwestern United States is characterized by limited
annual precipitation, which means limited annual recharge of
groundwater aquifers; even modest changes in groundwater levels from
groundwater pumping can affect above-ground stream flow as evidenced by
depleted flows in the Santa Cruz, Verde, San Pedro, Blue, and lower
Gila rivers as a result of regional groundwater demands (Stromberg et
al. 1996, pp. 113, 124-128; Rinne et al. 1998, p. 9; Voeltz 2002, pp.
45-47, 69-71; Haney et al. 2009 p. 1). Groundwater demands are expected
to reduce surface water flow in Arivaca Creek, Babocomari River, lower
Cienega Creek, San Pedro River, upper Verde River, and Agua Fria River
over the next several decades (Haney et al. 2009 p. 3, Table 2), which
historically or currently support northern Mexican or narrow-headed
gartersnake populations. If

[[Page 38705]]

surface flow is lost entirely from additional stress caused by drought
induced by projected climate change in the Southwest, local or regional
extirpations of both gartersnake species are likely to occur.
Water depletion is a concern for the Verde River (Garner et al.
2013, entire). For example, the City of Prescott, Arizona, experienced
a 22 percent increase in population between 2000 and 2005 (U.S. Census
Bureau 2010, p. 1), averaging around 4 percent growth per year (City of
Prescott 2010, p. 1). In addition, the towns of Prescott Valley and
Chino Valley experienced growth rates of 66 and 67 percent,
respectively (Arizona Department of Commerce 2009a, p. 1; 2009b, p. 1).
This growth is facilitated by groundwater pumping in the Verde River
basin. In 2004, the cities of Prescott and Prescott Valley purchased a
ranch in the Big Chino basin in the headwaters of the Verde River, with
the intent of drilling new wells to supply up to approximately 5
million cubic meters (4,000 acre-feet (AF)) of groundwater per year.
Barnett and Hawkins (2002, Table 4) reported population census data
from 1970, as well as projections for 2030, for communities situated
along the middle Verde River or within the Verde River subbasin as a
whole, such as Clarkdale, Cottonwood, Jerome, and Sedona. From 1970-
2000, population growth was recorded as Clarkdale (384 percent),
Cottonwood (352 percent), Jerome (113 percent), and Sedona (504
percent) (Barnett and Hawkins 2002, Table 4). Projected growth in these
same communities from 1970-2030 was tabulated at Clarkdale (620
percent), Cottonwood (730 percent), Jerome (292 percent), and Sedona
(818 percent) (Barnett and Hawkins 2002, Table 4).
Garner et al. (2013, p. 5) found that the Verde Valley population
grew 13 percent in 10 years from 63,000 in 2000 to 71,000 in 2010.
These examples of documented and projected population growth within the
Verde River subbasin indicate ever-increasing water demands that have
impacted base flow in the Verde River and are expected to continue. The
middle and lower Verde River has limited or no flow during portions of
the year due to agricultural diversion and upstream impoundments, and
it has several impoundments in its middle reaches, which could expand
the area of impacted northern Mexican and narrow-headed gartersnake
habitat. Blasch et al. (2006, p. 2) suggests that groundwater storage
in the Verde River subbasin has already declined due to groundwater
pumping and reductions in natural channel recharge resulting from
stream flow diversions.
Scientific studies have shown a link between the Big Chino aquifer
and spring flows that form the headwaters of the Verde River. It is
estimated that 80 to 86 percent of baseflow in the upper Verde River
comes from the Big Chino aquifer (Wirt 2005, p. G8). An in-depth
discussion of the potential effects to the Verde River from pumping of
the Big Chino Aquifer is available in Marder (2009, pp. 183-189).
However, while these withdrawals could potentially dewater the upper 26
mi (42 km) of the Verde River (Wirt and Hjalmarson 2000, p. 4; Marder
2009, pp. 188-189), it is uncertain that this project will occur given
the cost and administrative challenges it faces. An agreement in
principle was signed among the Salt River Project, the City of
Prescott, and Town of Prescott Valley to work toward resolution of
water rights in the Verde watershed, and, in 2012, Comprehensive
Agreement No. 1, which established monitoring and modeling plans, was
entered into. Within the Verde River subbasin, and particularly within
the Verde Valley, where the northern Mexican and narrow-headed
gartersnakes could occur, several other activities continue to threaten
surface flows (Rinne et al. 1998, p. 9; Paradzick et al. 2006, pp. 104-
110).
Portions of the Verde River or its tributaries are permanently or
seasonally dewatered by water diversions for agriculture (Paradzick et
al. 2006, pp. 104-110). The demands for surface water allocations from
rapidly growing communities and agricultural and mining interests have
altered flows or dewatered significant reaches during the spring and
summer months in some of the Verde River's larger, formerly perennial
tributaries such as Wet Beaver Creek, West Clear Creek, and the East
Verde River (Girmendonk and Young 1993, pp. 45-47; Sullivan and
Richardson 1993, pp. 38-39; Paradzick et al. 2006, pp. 104-110), which
may have supported either the northern Mexican or narrow-headed
gartersnake, or both. Groundwater pumping in the Tonto Creek drainage
regularly eliminates surface flows during parts of the year (Abarca and
Weedman 1993, p. 2).
Further south in Arizona, portions of the once-perennial San Pedro
River are now ephemeral, and water withdrawals are a concern for the
San Pedro River (USGS 2013, p. 3). The Cananea Mine in Sonora, Mexico,
owns the land surrounding the headwaters of the San Pedro. There is
disagreement on the exact amount of water withdrawn by the mine,
Mexicana de Cananea, which is one of the largest open-pit copper mines
in the world. However, there is agreement that it is the largest water
user in the basin (Harris et al. 2001, p. 213; Varady et al. 2000, p.
232). Along the upper San Pedro River, Stromberg et al. (1996, pp. 124-
127) found that wetland herbaceous species, important as cover for
northern Mexican gartersnakes, are the most sensitive to the effects of
a declining groundwater level. Webb and Leake (2005, pp. 302, 318-320)
described a correlative trend regarding vegetation along southwestern
streams from historically being dominated by marshy grasslands
preferable to northern Mexican gartersnakes, to currently being
dominated by woody species that are more tolerant of declining water
tables due to their deeper rooting depths. The cone of depression
associated with regional groundwater pumping is expected to continue
expanding its influence on surface flow in the San Pedro River over the
next several decades, which is expected to further reduce surface flow
in the river and negatively affect riparian vegetation (Stromberg et
al. 1996, pp. 124-128).
Another primary groundwater user in the San Pedro subbasin is Fort
Huachuca. Fort Huachuca is a U.S. Army installation located near Sierra
Vista, Arizona. Initially established in 1877 as a camp for the
military, the Fort has some of the earliest priority dates for water
rights in the state (Varady et al. 2000, p. 230). Fort Huachuca has
pursued a rigorous water use reduction plan, working over the past
decade to reduce groundwater consumption in the Sierra Vista subbasin.
Their efforts have focused primarily on reductions in groundwater
demand both on-post and off-post and increased artificial and enhanced
recharge of the groundwater system. Annual pumping from Fort Huachuca
production wells has decreased from a high of approximately 3,200 AF in
1989, to a low of approximately 1,400 AF in 2005. In addition, Fort
Huachuca and the City of Sierra Vista have increased the amount of
water recharged to the regional aquifer through construction of
effluent recharge facilities and detention basins that not only
increase stormwater recharge but mitigate the negative effects of
increased runoff from urbanization. The amount of effluent that was
recharged by Fort Huachuca and the City of Sierra Vista in 2005 was 426
AF and 1,868 AF, respectively. During this same year, enhanced
stormwater recharge at detention basins was estimated to be 129 AF. The
total net effect of all the combined efforts initiated by Fort Huachuca
has been to reduce the net groundwater

[[Page 38706]]

consumption by approximately 2,272 AF (71 percent) since 1989 (USFWS
2007b, pp. 41-42). Additional water conservation and recharge efforts
have since been implemented by Fort Huachuca and have reduced the
Fort's effect on baseflow in the upper San Pedro River to near zero, as
analyzed in a recent section 7 consultation (see http://www.fws.gov/southwest/es/arizona/Documents/Biol_Opin/120173_Fort%20HuachucaFINALBO_3.31.2014.pdf).
Groundwater withdrawal in Eagle Creek, primarily for water
supplying the large open-pit copper mine at Morenci, Arizona, dries
portions of the stream (Sublette et al. 1990, p. 19; USFWS 2005; Propst
et al. 1986, p. 7) that otherwise supports habitat for narrow-headed
gartersnakes. Mining is the largest industrial water user in
southeastern Arizona (ADWR Undated (accessed 2014), p. 62). The Morenci
mine on Chase Creek is North America's largest producer of copper,
covering approximately 24,281 hectares (ha) (60,000 acres (ac)). Water
for the Morenci mine is pumped from the Black River as an inter-basin
transfer via pipeline and open channel to Willow Creek, an east-flowing
tributary to Eagle Creek, then downstream more than 30 stream miles (50
km) to a facility where water is withdrawn and pumped uphill to the
mine in the adjacent Chase Creek drainage (Arizona Department of Water
Resources 2009, p. 1; Marsh 2013, pers. comm.). We are not aware of
plans for the closure of the Morenci Mine over the next several years,
and as the price for copper increases, the demand for copper mining
will increase into the future.
The Rosemont Copper Mine proposed to be constructed in the
northeastern area of the Santa Rita Mountains in Santa Cruz County,
Arizona, will include a mine pit that will be excavated to a depth
greater than that of the regional aquifer. Water will thus drain from
storage in the aquifer into the pit. The need to dewater the pit during
mining operations will thus result in ongoing removal of aquifer water
storage. Upon cessation of mining, a pit lake will form, and
evaporation from this water body will continue to remove water from
storage in the regional aquifer. This aquifer also supplies baseflow to
Cienega Creek, immediately east of the proposed project site. Several
groundwater models have been developed to analyze potential effects of
expected groundwater withdrawals. The latest independent models
indicate that a potentially significant reduction to baseflows in
Cienega Creek and Emprire Gulch are expected within 50 years post-
closure of the Rosemont Copper Mine, should it be permitted for
development (see http://www.rosemonteis.us/final-eis).
The best available scientific and commercial information indicates
that any reduction in the presence or availability of water is a
significant threat to northern Mexican and narrow-headed gartersnakes,
their prey base, and their habitat. This is because water is a
fundamental need that supports the necessary aquatic and riparian
habitats and prey species needed by both species of gartersnake.
Through GIS analyses, we found that approximately 32 percent of
formerly perennial streams have been dewatered within the historical
distribution of the northern Mexican gartersnake. Within the historical
distribution of the narrow-headed gartersnake, approximately 13 percent
of formerly perennial streams have been dewatered. With continued human
population growth and corresponding water use throughout the range of
both gartersnakes, we expect the loss of habitat due to reduction in
stream flows to increase in the foreseeable future and result in
additional declines and extirpations of gartersnake populations.
Climate Change and Drought (Northern Mexican and Narrow-headed
gartersnake)--Our analyses under the Act include consideration of
ongoing and projected changes in climate. The terms ``climate'' and
``climate change'' are defined by the Intergovernmental Panel on
Climate Change (IPCC). ``Climate'' refers to the mean and variability
of different types of weather conditions over time, with 30 years being
a typical period for such measurements, although shorter or longer
periods also may be used (IPCC 2007, p. 78). The term ``climate
change'' thus refers to a change in the mean or variability of one or
more measures of climate (e.g., temperature or precipitation) that
persists for an extended period, typically decades or longer, whether
the change is due to natural variability, human activity, or both (IPCC
2007, p. 78). Various types of changes in climate can have direct or
indirect effects on species. These effects may be positive, neutral, or
negative and they may change over time, depending on the species and
other relevant considerations, such as the effects of interactions of
climate with other variables (e.g., habitat fragmentation) (IPCC 2007,
pp. 8-14, 18-19). In our analyses, we use our expert judgment to weigh
relevant information, including uncertainty, in our consideration of
various aspects of climate change and their predicted effects on
northern Mexican and narrow-headed gartersnakes.
The ecology and natural histories of northern Mexican and narrow-
headed gartersnakes are strongly linked to water. As discussed above,
the northern Mexican gartersnake is a highly aquatic species and relies
largely upon other aquatic species, such as ranid frogs and native and
nonnative, soft-rayed fish as prey. The narrow-headed gartersnake is
the most aquatic of the southwestern gartersnakes and is a specialized
predator on native and nonnative, soft-rayed fish found primarily in
clear, rocky, higher elevation streams. Because of their aquatic
nature, they may be uniquely susceptible to environmental change,
especially factors associated with climate change (Wood et al. 2011, p.
3). Together, these factors are likely to make northern Mexican and
narrow-headed gartersnakes vulnerable to effects of climate change and
drought discussed below.
Several climate-related trends have been detected since the 1970s
in the southwestern United States, including increases in surface
temperatures, rainfall intensity, drought, heat waves, extreme high
temperatures, and average low temperatures (Overpeck 2008, entire).
Annual precipitation amounts in the southwestern United States may
decrease by 10 percent by the year 2100 (Overpeck 2008, entire). Seager
et al. (2007, pp. 1181-1184) analyzed 19 different computer models of
differing variables to estimate the future climatology of the
southwestern United States and northern Mexico in response to
predictions of changing climatic patterns. All but 1 of the 19 models
predicted a drying trend within the Southwest; one predicted a trend
toward a wetter climate (Seager et al. 2007, p. 1181). A total of 49
projections were created using the 19 models, and all but 3 predicted a
shift to increasing aridity (dryness) in the Southwest as early as
2021-2040 (Seager et al. 2007, p. 1181). Northern Mexican and
particularly narrow-headed gartersnakes, and their prey bases, depend
on permanent or nearly permanent water for survival. A large percentage
of habitats within the current distribution of northern Mexican and
narrow-headed gartersnakes are predicted to be at risk of becoming more
arid with reductions in snow pack levels by 2021-2040 (Seager et al.
2007, pp. 1183-1184). This has severe implications for the integrity of
aquatic and riparian ecosystems and the water that supports them.
In assessing potential effects of predicted climate change to river
systems in New Mexico, Molles (2007,

[[Page 38707]]

entire) found that: (1) Variation in stream flow will likely be higher
than variation in precipitation; (2) predicted effects such as warming
and drying are expected to result in higher variability in stream
flows; and (3) high-elevation fish and non-flying invertebrates (which
are prey for gartersnake prey species) are at greatest risk from
effects of predicted climate change. Enquist and Gori (2008, p. iii)
found that most of New Mexico's mid- to high-elevation forests and
woodlands have experienced either consistently warmer and drier
conditions or greater variability in temperature and precipitation from
1991 to 2005. However, Enquist et al. (2008, p. v) found the upper Gila
and San Francisco subbasins, which support narrow-headed gartersnake
populations, have experienced very little change in moisture stress
during the same period.
Cavazos and Arriaga (2010, entire) found that average temperatures
along the Mexican Plateau in Mexico could rise in the range of
1.8[emsp14][deg]F (1 [deg]C) to 9[emsp14][deg]F (5 [deg]C) in the next
20 years, according to their models. Cavazos and Arriaga (2010, entire)
also found that precipitation may decrease up to 12 percent over the
next 20 years in the same region, with pronounced decreases in winter
and spring precipitation.
Potential drought associated with changing climatic patterns may
adversely affect the amphibian prey base for the northern Mexican
gartersnake. Amphibians may be among the first vertebrates to exhibit
broad-scale changes in response to changes in global climatic patterns
due to their sensitivity to changes in moisture and temperature (Reaser
and Blaustein 2005, p. 61). Changes in temperature and moisture,
combined with the ongoing threat to amphibians from the persistence of
disease-causing bacteria such as Batrachochytrium dendrobatidis (Bd)
may cause prey species to experience increased physiological stress and
decreased immune system function, possibly leading to disease outbreaks
(Carey and Alexander 2003, pp. 111-121; Pounds et al. 2006, pp. 161-
167). Of the 30 different vertebrate species in the Sky Island region
of southeastern Arizona, the northern Mexican gartersnake was found to
be the fifth most vulnerable (total combined score) to predicted
climate change; one of its primary prey species, the Chiricahua leopard
frog, was determined to be the fourth most vulnerable (Coe et al. 2012,
p. 16). Both the northern Mexican gartersnake and the Chiricahua
leopard frog ranked the highest of all species assessed for
vulnerability of their habitat to predicted climate change, and the
Chiricahua leopard frog was also found to be the most vulnerable in
terms of its physiology (Coe et al. 2012, p. 18). Relative uncertainty
for the vulnerability assessment provided by Coe et al. (2012, Table
2.2) ranged from 0 to 8 (higher score means greater uncertainty), and
the northern Mexican gartersnake score was 3, meaning that the
vulnerability assessment was more certain than not. Coe et al. (2012,
entire) focused their assessment of species vulnerability to climate
change on those occurring on the Coronado National Forest in
southeastern Arizona. However, it is not unreasonable to hypothesize
that results might be applicable in a larger, regional context as
applied in most climate models.
The bullfrog, also assessed by Coe et al. (2012, pp. 16, 18, Table
2.2), was shown to be significantly less vulnerable to predicted
climate change than either northern Mexican gartersnakes or Chiricahua
leopard frogs with an uncertainty score of 1 (very certain). We suspect
bullfrogs were found to be less vulnerable by Coe et al. (2012) to
predicted climate change in southeastern Arizona due to their dispersal
and colonization capabilities, capacity for self-sustaining
cannibalistic populations, and ecological dominance where they occur.
Based upon climate change models, nonnative species biology, and
ecological observations, Rahel et al. (2008, p. 551) concluded that
climate change could foster the expansion of nonnative aquatic species
into new areas, magnify the effects of existing aquatic nonnative
species where they currently occur, increase nonnative predation rates,
and heighten the virulence of disease outbreaks in North America.
Rahel and Olden (2008, p. 526) expect that increases in water
temperatures in drier climates such as the southwestern United States
will result in periods of prolonged low flows and stream drying. These
effects from changing climatic conditions may have profound effects on
the amount, permanency, and quality of habitat for northern Mexican and
narrow-headed gartersnakes as well as their prey base. Changes in
amount or type of winter precipitation may affect snowpack levels as
well as the timing of their discharge into high-elevation streams. Low
or no snowpack levels would jeopardize the amount and reliability of
stream flow during the arid spring and early summer months, which would
increase water temperatures to unsuitable levels or eliminate flow
altogether. Harmful nonnative species such as largemouth bass are
expected to benefit from prolonged periods of low flow (Rahel and Olden
2008, p. 527). These nonnative predatory species evolved in river
systems with hydrographs that were largely stable, not punctuated by
flood pulses in which native species evolved and benefit from. Propst
et al. (2008, p. 1246) also suggested that nonnative fish species may
benefit from drought.
Changes to climatic patterns may warm water temperatures, alter
stream flow events, and increase demand for water storage and
conveyance systems (Rahel and Olden 2008, pp. 521-522). Warmer water
temperatures across temperate regions are predicted to expand the
distribution of existing harmful nonnative species, which evolved in
warmer water temperatures, by providing 31 percent more suitable
habitat. This conclusion is based upon studies that compared the
thermal tolerances of 57 fish species with predictions made from
climate change temperature models (Mohseni et al. 2003, p. 389). Eaton
and Scheller (1996, p. 1,111) reported that, while several cold-water
fish species (such as trout, a prey species for narrow-headed
gartersnakes) in North America are expected to have reductions in their
distribution from effects of climate change, several harmful nonnative
species are expected to increase their distribution. In the
southwestern United States, this situation may occur where the quantity
of water is sufficient to sustain effects of potential prolonged
drought conditions but where water temperature may warm to a level
found suitable to harmful nonnative species that were previously
physiologically precluded from occupation of these areas. Species that
are particularly harmful to northern Mexican and narrow-headed
gartersnake populations, such as the green sunfish, channel catfish,
largemouth bass, and bluegill, are expected to increase their
distribution by 7.4 percent, 25.2 percent, 30.4 percent, and 33.3
percent, respectively (Eaton and Scheller 1996, p. 1,111).
Vanishing Cienegas (Northern Mexican Gartersnake)--Cienegas are
particularly important habitat for the northern Mexican gartersnake
because these areas present ideal habitat characteristics for the
species and its prey base and have been shown to support robust
populations of both (Rosen and Schwalbe 1988, p. 14). Hendrickson and
Minckley (1984, p. 131) defined cienegas as ``mid-elevation (3,281-
6,562 ft (1,000-2000 m)) wetlands characterized by permanently
saturated, highly organic, reducing (lowering of oxygen level) soils.''
Many of these unique communities of the southwestern United States,
Arizona in

[[Page 38708]]

particular, and Mexico have been lost in the past century to streambed
modification, intensive livestock grazing, woodcutting, artificial
drainage structures, stream flow stabilization by upstream dams,
channelization, and stream flow reduction from groundwater pumping and
water diversions (Hendrickson and Minckley 1984, p. 161). Stromberg et
al. (1996, p. 114) state that cienegas were formerly extensive along
streams of the Southwest; however, most were destroyed during the late
1800s, when groundwater tables declined several meters and stream
channels became incised. Drying trends are expected to continue into
the next several decades and likely beyond.
Development and Recreation Within Riparian Corridors (Northern
Mexican and Narrow-headed Gartersnake)--Development within and adjacent
to riparian areas has proven to be a significant threat to riparian
biological communities and their suitability for native species (Medina
1990, p. 351; Nowak and Santana-Bendix 2002, p. 37). Riparian
communities are sensitive to even low levels (less than 10 percent) of
urban development within a subbasin (Wheeler et al. 2005, p. 142).
Development along or within proximity to riparian zones can alter the
nature of stream flow dramatically, changing once-perennial streams
into ephemeral streams, which has direct consequences on the riparian
community (Medina 1990, pp. 358-359). Medina (1990, pp. 358-359)
correlated tree density and age class representation to stream flow in
a high-elevation system with a narrow alluvium basin, finding that
decreased flow reduced tree densities and generally resulted in few to
no small-diameter trees. Small-diameter trees assist northern Mexican
and narrow-headed gartersnakes by providing additional habitat
complexity, thermoregulatory opportunities, and cover needed to reduce
predation risk and enhance the usefulness of areas for maintaining
optimal body temperature. Development along lower elevation streams
with broad alluvial basins may have different effects on stream flow
and riparian vegetation, as compared to high-elevation streams. The
presence of small shrubs and trees may be particularly important for
the narrow-headed gartersnake (Deganhardt et al. 1996, p. 327).
Development within occupied riparian habitat also likely increases the
number of human-gartersnake encounters and, therefore, the frequency of
adverse human interaction, described below.
Obvious examples of the influence of urbanization and development
can be observed within the areas of greater Tucson and Phoenix,
Arizona, where impacts have modified riparian vegetation, structurally
altered stream channels, facilitated nonnative species introductions,
and dewatered large reaches of formerly perennial rivers where the
northern Mexican gartersnake historically occurred (Santa Cruz, lower
Gila, and lower Salt Rivers, respectively). Urbanization and
development of these areas, along with the introduction of nonnative
species, are largely responsible for the likely extirpation of the
northern Mexican gartersnake from these regions.
Development near riparian areas usually leads to increased
recreation. Riparian areas located near urban areas are vulnerable to
the effects of increased recreation. An example of such an area within
the existing distribution of both the northern Mexican and narrow-
headed gartersnake is the Verde Valley. The reach of the Verde River
that winds through the Verde Valley receives a high amount of
recreational use from people living in central Arizona (Paradzick et
al. 2006, pp. 107-108). Increased human use results in the trampling of
near-shore vegetation, which reduces cover for gartersnakes, especially
newborns. Increased human visitation in occupied habitat also increases
the potential for adverse human interactions with gartersnakes, which
frequently leads to the capture, injury, or death of the snake (Rosen
and Schwalbe 1988, p. 43; Ernst and Zug 1996, p. 75; Green 1997, pp.
285-286; Nowak and Santana-Bendix 2002, pp. 37-39).
Oak Creek Canyon, which represents an important source population
for narrow-headed gartersnakes, is also a well-known example of an area
with very high recreation levels (Nowak and Santana-Bendix 2002, p.
37). In 1995, 1.3 million people visited the Red Rock Ranger District,
which includes Oak Creek Canyon and the Sedona, Arizona area; that
figure climbed to six million visitors by 1999 (Nowak and Santana-
Bendix 2002, p. 37). Recreational activities in the Southwest are often
heavily tied to water bodies and riparian areas, due to the general
lack of surface water on the landscape. Increased recreational impacts
on the quantity and quality of water, as well as the adjacent
vegetation, negatively affect northern Mexican and narrow-headed
gartersnakes. The impacts to riparian habitat from recreation can
include movement of people or livestock, such as horses or mules, along
stream banks, trampling, loss of vegetation, and increased danger of
fire starts (Northern Arizona University 2005, p. 136; Monz et al.
2010, pp. 553-554).
High stream-side recreation levels can result in increased
siltation of streams, which can result in lower recruitment rates of
native fish and, therefore, negatively affect the prey base for narrow-
headed gartersnakes (Nowak and Santana-Bendix 2002, pp. 37-38). In the
arid Gila River Basin, recreational impacts are disproportionately
distributed along streams as a primary focus for recreation (Briggs
1996, p. 36). Within the range of the northern Mexican and narrow-
headed gartersnakes in the United States, the majority of the occupied
areas occur on Federal lands, which are managed for recreation and
other purposes. On the Gila National Forest, and associated private,
state, or non-Forest Service inholdings in the area, heavy recreation
use can affect gartersnakes within occupied narrow-headed gartersnake
habitat along the Middle Fork Gila River, the West Fork Gila River
between Cliff Dwellings and Little Creek, and Whitewater Creek from the
Catwalk to Glenwood (Hellekson 2012a, pers. comm.). Much of the
recreation use in these areas is related to hiking and backpacking,
which are not a threat to gartersnakes except when increased human
visitation leads to more gartersnake encounters and potentially more
killing of gartersnakes where the foot trail is near the canyon bottom
(see ``Adverse Human Interactions with Gartersnakes'' below).
Urbanization on smaller scales can also impact habitat suitability
and the prey base for the northern Mexican or narrow-headed
gartersnakes, such as along Tonto Creek, within the Verde Valley, and
the vicinity of Rock Springs along the Agua Fria River (Girmendonk and
Young 1997, pp. 45-52; Voeltz 2002, pp. 58-59, 69-71; Holycross et al.
2006, pp. 53, 56; Paradzick et al. 2006, pp. 89-90). One of the more
stable populations of the northern Mexican gartersnake in the United
States, at the Page Springs and Bubbling Ponds fish hatcheries along
Oak Creek, is likely to be affected by future small-scale development
over the next decade. As mitigation for effects to species covered
under their habitat conservation plan for the operation of Horseshoe
and Bartlett Reservoirs on the Verde River, the Salt River Project will
be funding development improvements and capacity expansion at these
State-owned and operated hatcheries for the purpose of creating a
native fish hatchery. Construction is likely to include the replacement
of earthen ponds currently used by the gartersnakes, with modernized
non-earthen units. However, the AGFD is committed to

[[Page 38709]]

maintaining the healthy population of northern Mexican gartersnakes at
these hatcheries, and is investigating land use options to improve
gartersnake habitat. A variety of activities associated with ongoing
and future operation of the hatchery is likely to contribute to some
level of fatality in resident gartersnakes, but that level might be
offset by a mitigation strategy when adopted.
Diminishing Water Quantity and Quality in Mexico (Northern Mexican
Gartersnake)--While effects to riparian and aquatic communities affect
both the northern Mexican gartersnake and the narrow-headed gartersnake
in the United States, Mexico provides habitat only for the northern
Mexican gartersnake. Threats to northern Mexican gartersnake habitat in
Mexico include intensive livestock grazing, urbanization and
development, water diversions and groundwater pumping, loss of
vegetation cover and deforestation, and erosion, as well as
impoundments and dams that have modified or destroyed riparian and
aquatic communities in areas of Mexico where the species occurred
historically. Rorabaugh (2008, pp. 25-26) noted threats to northern
Mexican gartersnakes and their native amphibian prey base in Sonora,
which included disease, pollution, intensive livestock grazing,
conversion of land for agriculture, nonnative plant invasions, and
logging.
Illegal or under-regulated logging in the Sierra Madre of Mexico,
and particularly within Chihuahua (Sierra Tarahumara), has been
identified as a significant environmental concern (Gingrich 1993,
entire). Gingrich (1993, p. 6) described the risk to streams from
excessive logging in the Sierra Madre as including increased flooding,
increased sedimentation, and lower baseflows. In an attempt to reverse
disturbing trends in logging practices, the World Wildlife Fund-Mexico
(2004, entire) has begun implementing a conservation plan for the
Sierra Tarahumara region. Ramirez Bautista and Arizmendi (2004, p. 3)
stated that the principal threats to northern Mexican gartersnake
habitat in Mexico include the drying of temporary ponds, livestock
grazing, deforestation, wildfires, and human settlements. In addition,
nonnative species, such as bullfrogs and nonnative, predatory fish,
have been introduced throughout Mexico and continue to disperse
naturally, broadening their distributions (Conant 1974, pp. 487-489;
Miller et al. 2005, pp. 60-61; Luja and Rodr[iacute]guez-Estrella 2008,
pp. 17-22).
Mexico's water needs for urban and agricultural development, as
well as impacts to aquatic habitat from these uses, are linked to
significant human population growth over the past century in Mexico.
Mexico's human population grew 700 percent from 1910 to 2000 (Miller et
al. 2005, p. 60). Mexico's population increased by 245 percent from
1950 to 2002 and is projected to grow by another 28 percent by 2025
(EarthTrends 2005, p. 1). Growth is concentrated in Mexico's northern
states (Stoleson et al. 2005, Table 3.1) and is now skewed towards
urban areas (Miller et al. 2005, p. 60). The human population of
Sonora, Mexico, doubled in size from 1970 (1.1 million) to 2000 (2.2
million) (Stoleson et al. 2005, p. 54). The population of Sonora is
expected to increase by 23 percent, to 2.7 million people, in 2020
(Stoleson et al. 2005, p. 54). Increasing trends in Mexico's human
population will continue to place additional stress on the country's
freshwater resources and continue to be the catalyst for the
elimination of northern Mexican gartersnake habitat and prey species.
Much knowledge of the status of aquatic ecosystems in Mexico has
come from fisheries research, which is particularly applicable to
assessing the status of northern Mexican gartersnakes because of the
gartersnakes' ecology and relationship to other aquatic and riparian
vertebrates. Fisheries research is particularly applicable because of
the role fishes serve as indicators of the status of the aquatic
community as a whole. Miller et al. (2005) reported information on
threats to freshwater fishes and riparian and aquatic communities in
specific water bodies from several regions throughout Mexico within the
range of the northern Mexican gartersnake: headwaters of the R[iacute]o
Lerma (extirpation of freshwater fish species, nonnative species,
pollution, dewatering, pp. 60, 105, 197); medium-sized streams
throughout the Sierra Madre Occidental (localized extirpations,
logging, dewatering, pp. 109, 177, 247); the R[iacute]o Conchos
(extirpations of freshwater fish species, p. 112); the r[iacute]os
Casas Grandes, Santa Mar[iacute]a, del Carmen, and Laguna Bustillos
(water diversions, groundwater pumping, channelization, flood control
practices, pollution, and introduction of nonnative species, pp. 124,
197); the R[iacute]o Santa Cruz (extirpations, p. 140); the R[iacute]o
Yaqui (dewatering, nonnative species, p. 148, Plate 61, p. 247); the
R[iacute]o Colorado (nonnative species, p. 153); the r[iacute]os Fuerte
and Culiac[aacute]n (logging, p. 177); canals, ponds, lakes in the
Valle de M[eacute]xico (nonnative species, extirpations, pollution, pp.
197, 281); the R[iacute]o Verde Basin (dewatering, nonnative species,
extirpations, Plate 88); the R[iacute]o Mayo (dewatering, nonnative
species, p. 247); the R[iacute]o Papaloapan (pollution, p. 252); and
the R[iacute]o P[aacute]nuco Basin (nonnative species, p. 295). These
examples should not be construed as to suggest that all native fishes
are threatened and all aquatic habitat or ecosystems are in peril.
Rather, these examples suggest that threats may be localized in some
examples and wider-ranging in others, but collectively several types of
threats are acting in various degrees across numerous drainages in
Mexico, throughout the range of the northern Mexican gartersnake. This
provides some level of insight into the status of native aquatic
ecosystems within its range.
Excessive sedimentation also appears to be a significant problem
for aquatic habitat in Mexico. Recent estimates indicate that 80
percent of Mexico is affected by soil erosion caused by vegetation
removal related to grazing, fires, agriculture, deforestation, etc. The
most serious erosion is occurring in the states of Guanajuato (43
percent of the state's land area), Jalisco (25 percent of the state's
land area), and M[eacute]xico (25 percent of the state's land area)
(Landa et al. 1997, p. 317), all of which occur within the distribution
of the northern Mexican gartersnake. Miller et al. (2005, p. 60) stated
that ``During the time we have collectively studied fishes in
M[eacute]xico and southwestern United States, the entire biotas of long
reaches of major streams such as the R[iacute]o Grande de Santiago
below Guadalajara (Jalisco) and R[iacute]o Colorado (lower Colorado
River in Mexico) downstream of Hoover (Boulder) Dam (in the United
States), have simply been destroyed by pollution and river
alteration.'' These streams are within the distribution of the northern
Mexican gartersnake. The geographic extent of threats reported by
Miller et al. (2005) across the distribution of the northern Mexican
gartersnake in Mexico is evidence that they are widespread through the
country, and encompass a large proportion of the distribution of the
northern Mexican gartersnake in Mexico.
In northern Mexico, effects of development, which is expected to
continue at similar rates, if not increase, over the next several
decades, such as agriculture and irrigation practices on streams and
rivers in Sonora have been documented at least as far back as the
1960s. Branson et al. (1960, p. 218) found that the perennial rivers
that drain the ``mountains'' (Sierra Madre) are ``silt-laden and
extremely turbid, mainly because of irrigation practices.'' Specific
rivers were not identified where Branson et al. (1960, p. 218)

[[Page 38710]]

describes the effects of irrigation practices, but the Sierra Madre in
Sonora is within the known distribution of the northern Mexican
gartersnake in Mexico and, therefore, suggests that at least some
portion of occupied habitat has been adversely impacted by these
practices. Smaller mountain streams, such as the Rio Nacozari in Sonora
were found to be ``biological deserts'' from the effects of numerous
local mining practices (Branson et al. 1960, p. 218). The perennial
rivers and their mountain tributaries that may have been historically
occupied by northern Mexican gartersnakes (as well as their prey
species) have since been adversely affected, which likely contributed
to declines in these areas.
Minckley et al. (2002, pp. 687-705) provided a summary of threats
(p. 696) to two newly described (at the time) species of pupfish and
their habitat in Chihuahua, Mexico, which occur with the northern
Mexican gartersnake and comprise part of its prey base. Initial
settlement and agricultural development of the area resulted in
significant channel cutting through soil layers protecting the alluvial
plain above them, which resulted in reductions in the base level of
each basin in succession (Minckley et al. 2002, p. 696). Related to
these activities, the building of dams and diversion structures dried
entire reaches of some regional streams and altered flow patterns of
others (Minckley et al. 2002, p. 696). This was followed by groundwater
pumping (enhanced by the invention of the electric pump), which lowered
groundwater levels and dried up springs and small channels and reduced
the reliability of baseflow in ``essentially all systems'' (Minckley et
al. 2002, p. 696). Subsequently, the introduction and expansion of
nonnative species in the area successfully displaced or extirpated many
native species (Minckley et al. 2002, p. 696). Conant (1974, pp. 486-
489) described significant threats to northern Mexican gartersnake
habitat within its distribution in western Chihuahua, Mexico, and
within the Rio Concho system where it occurs. These threats included
impoundments, water diversions, and purposeful introductions of
largemouth bass, common carp, and bullfrogs.
In the central portions of the northern Mexican gartersnakes' range
in Mexico, such as in Durango, Mexico, population growth since the
1960s has led to regional effects such as reduced stream flow,
increased water pollution, and largemouth bass introductions, which
``have seriously affected native biota'' (Miller et al. 1989, p. 26).
McCranie and Wilson (1987, p. 2) discuss threats to the pine-oak
communities of higher elevation habitats (within the distribution of
the northern Mexican gartersnake) in the Sierra Madre Occidental in
Mexico, specifically noting that ``. . . the relative pristine
character of the pine-oak woodlands is threatened . . . every time a
new road is bulldozed up the slopes in search of new madera or
pasturage. Once the road is built, further development follows; pueblos
begin to pop up along its length. . . .'' Several drainages that
possess suitable habitat for the northern Mexican gartersnake occur in
the area referenced above by McCranie and Wilson (1987, p. 2),
including the Rio de la Cuidad, Rio Quebrada El Salto, Rio Chico, Rio
Las Bayas, Rio El Cigarrero, Rio Galindo, Rio Santa Barbara, and the
Rio Chavaria.
In the southern portion of the northern Mexican gartersnake's range
in Mexico, growth and development around Mexico City resulted in
agricultural practices and groundwater demands that dewatered aquatic
habitat and led to declines, and in some cases, extinctions of local
native fish species (Miller et al. 1989, p. 25). Considerable research
has been focused in the central and west-central regions of Mexico,
within the southern portion of the northern Mexican gartersnake's
range, where native fish endemism (unique, narrowly distributed suite
of species) is high, as are threats to their populations and habitat.
Since the 1970s in central Mexico, significant human population growth
has resulted in the overexploitation of local fisheries and water
pollution; these factors have accelerated the degradation of stream and
riverine habitats and led to fish communities becoming reduced or
undergoing significant changes in structure and composition (Mercado-
Silva et al. 2002, p. 180).
These shifts in fish community composition, population density, and
shrinking distributions have adversely affected the northern Mexican
gartersnake prey base in the southern portion of its range in Mexico.
The Lerma River basin is the largest in west-central Mexico and is
within the distribution of the northern Mexican gartersnake in the
states of Jalisco, Guanajuato, and Quer[eacute]taro in the southern
portion of its range. Lyons et al. (1995, p. 572) reported that many
fish communities in large perennial rivers, isolated spring-fed
streams, or spring sources themselves of this region have been
``radically restructured'' and are now dominated by a few nonnative,
generalist species. Lowland streams and rivers in this region are used
heavily for irrigation and are polluted by industrial, municipal, and
agricultural discharges (Lyons and Navarro-Perez 1990, p. 37; Lyons et
al. 1995, p. 572).
Native fish communities of west-central Mexico have been found to
be in serious decline as a result of habitat degradation at an
``unprecedented'' rate due to water withdrawals (diversions for
irrigation), as well as untreated municipal, industrial, and
agricultural discharges (Lyons et al. 1998, pp. 10-11). Numerous dams
have been built along the Lerma River and along its major tributaries
to support one of Mexico's most densely populated regions during the
annual dry period; the water is used for irrigation, industry, and
human consumption (Lyons et al. 1998, p. 11). From 1985 to 1993, Lyons
et al. (1998, p. 12) found that 29 of 116 (25 percent) fish sampling
locations visited within the Lerma River watershed were completely dry
and another 30 were too polluted to support a fish community. These
figures indicate that over half of the localities visited by Lyons et
al. (1998, p. 12) that maintained fish populations prior to 1985 no
longer support fish, which has likely adversely affected local northern
Mexican gartersnake populations, and perhaps led to population declines
or extirpations.
Soto-Galera et al. (1999, p. 137) reported fish and water quality
sampling results from within the Rio Grande de Morelia-Lago de Cuitzeo
Basin of Michoac[aacute]n and Guanajuato, Mexico. The easternmost
portion of this basin occurs at the periphery of the known northern
Mexican gartersnake range in Mexico. Soto-Galera et al. (1999, p. 137)
found that over the past several decades, diminishing water quantity
and worsening water quality have resulted in the elimination of 26
percent of native fish species from the basin, the extinction of two
species of native fish, and declining distributions of the remaining 14
species. These figures suggest significant concern for aquatic
ecosystems of this region. Some conservation value, however, is
realized when headwaters, springs, and small streams are protected as
parks or municipal water supplies (Lyons et al. 1998, p. 15), but these
efforts do little to protect larger perennial rivers that represent
valuable habitat for northern Mexican gartersnakes.
Mercado-Silva et al. (2002, Appendix 2) reported results from fish
community sampling and habitat assessments along 63 sites across
central Mexico; the easternmost of these sites include most of the
northern Mexican gartersnake's southern range. Specifically, sampling
locations in the Balsas, Lerma, Morelia, P[aacute]nuco Moctezuma, and
P[aacute]nuco

[[Page 38711]]

Tampa[oacute]n basins each occurred within the range of the northern
Mexican gartersnake in the states of Guanajuato, Queretaro, Mexico, and
Puebla; approximately 30 locations in total. The purpose of this
sampling effort was to score each site in terms of its index of biotic
integrity (IBI) and environmental quality (EQ), with a score of 100
representing the optimum score for each category. The IBI scoring
method has been verified as a valid means to quantitatively assess
ecosystem integrity at each site (Lyons et al. 1995, pp. 576-581;
Mercado-Silva et al. 2002, p. 184). The range in IBI scores in these
sampling locations was 85 to 35, and the range in EQ scores was 90 to
50 (Mercado-Silva et al. 2002, Appendix 2). The average IBI score was
57, and the average EQ score was 74, across all 30 sites and all 4
basins (Mercado-Silva et al. 2002, Appendix 2). According to the
qualitative equivalencies assigned to scores (Mercado-Silva et al.
2002, p. 184), these values indicate that the environmental quality
score averaged across all 30 sites was ``good'' and the biotic
integrity scores were ``fair.'' It should be noted that 14 of the 30
sites sampled had IBI scores equal to or less than 50, and 5 of those
ranked as ``poor.'' Of all the basins throughout central Mexico that
were scored in this exercise, the two P[aacute]nuco basins represented
20 of the 30 sites sampled and scored the worst of all basins (Mercado-
Silva et al. 2002, p. 186). This indicates that threats to the northern
Mexican gartersnake, its prey base, and its habitat pose the greatest
risk in this portion of its range in Mexico.
Near Torre[oacute]n, Coahuila, where the northern Mexican
gartersnake occurs, groundwater pumping has resulted in flow reversal,
which has dried up many local springs, drawn arsenic-laden water to the
surface, and resulted in adverse human health effects in that area
(Miller et al. 2005, p. 61). Severe water pollution from untreated
domestic waste is evident downstream of large Mexican cities, such as
Mexico City, and inorganic pollution from nearby industrialized areas
and agricultural irrigation return flow has dramatically affected
aquatic communities through contamination (Miller et al. 2005, p. 60).
Miller et al. (2005, p. 61) provide an excerpt from Soto Galera et al.
(1999) addressing the threats to the R[iacute]o Lerma, Mexico's longest
river, which is occupied by the northern Mexican gartersnake: ``The
basin has experienced a staggering amount of degradation during the
20th Century. By 1985-1993, over half of our study sites had
disappeared or become so polluted that they could no longer support
fishes. Only 15 percent of the sites were still capable of supporting
sensitive species. Forty percent (17 different species) of the native
fishes of the basin had suffered major declines in distribution, and
three species may be extinct. The extent and magnitude of degradation
in the R[iacute]o Lerma basin matches or exceeds the worst cases
reported for comparably sized basins elsewhere in the world.''
In the Transvolcanic Belt Region of the states of Jalisco, Mexico,
and Veracruz in southern Mexico, Conant (2003, p. 4) noted that water
diversions, pollution (e.g., discharge of raw sewage), sedimentation of
aquatic habitats, and increased dissolved nutrients were resulting in
decreased dissolved oxygen in suitable northern Mexican gartersnake
habitat. Conant (2003, p. 4) stated that many of these threats were
evident during his field work in the 1960s, and that they are
``continuing with increased velocity.''
High-Intensity Wildfires and Sedimentation of Aquatic Habitat (Narrow-
Headed Gartersnake)
High-intensity wildfires lead to excessive sedimentation and ash
flows in streams, which can, in turn, result in sharp declines, and
even complete elimination, in fish communities downstream. According to
the Apache-Sitgreaves National Forest forested vegetation types,
historic fire-return intervals varied from frequent, low-intensity
surface fires in ponderosa pine types (every 2-17 years), to mixed-
severity fires in wet mixed-conifer forests (every 35-50 years), to
high-severity, stand-replacement fires of the spruce-fir ecosystems
(every 150-400 years) (U.S. Forest Service (USFS) 2013). Low-intensity
fire has been a common, natural disturbance factor in forested
landscapes for centuries prior to European settlement (Rinne and Neary
1996, pp. 135-136). Rinne and Neary (1996, p. 143) concluded that
existing wildfire suppression policies intended to protect the
expanding number of human structures on forested public lands have
altered the fuel loads in these ecosystems and increased the
probability of high-intensity wildfires.
Climate change-driven drought cycles are also likely contributing
to a changing fire regime in the west (Westerling et al. (2006, pp.
941-943). Westerling et al. (2006, p. 940) showed that ``large wildfire
activity (in the western United States) increased suddenly and markedly
in the mid-1980s, with higher large-wildfire frequency, longer wildfire
durations, and longer wildfire seasons.'' The effects of these high-
intensity wildfires include the removal of vegetation, the degradation
of subbasin condition, altered stream behavior, and increased
sedimentation of streams. These effects can harm fish communities, as
observed in the 1990 Dude Fire, when corresponding ash flows resulted
in fish kills in Dude Creek and the East Verde River (Voeltz 2002, p.
77). Fish kills, also discussed below, can drastically affect the
suitability of habitat for northern Mexican and narrow-headed
gartersnakes due to the removal of a portion or the entire prey base.
The Chiricahua leopard frog recovery plan cites altered fire regimes as
a serious threat to Chiricahua leopard frogs, a prey species for
northern Mexican gartersnakes (USFWS 2007a, pp. 38-39).
The nature and occurrence of wildfires in the Southwest is expected
to also be affected by climate change and ongoing and predicted future
drought. Current predictions of drought and/or higher winter low
temperatures may stress ponderosa pine forests in which the narrow-
headed gartersnake principally occurs, and may increase the frequency
and magnitude of wildfire. Ganey and Vojta (2010, entire) studied tree
mortality in mixed-conifer and ponderosa pine forests in Arizona from
1997-2007, a period of extreme drought. They found the mortality of
trees to be severe; the number of trees dying over a 5[hyphen]year
period increased by more than 200 percent in mixed[hyphen]conifer
forest and by 74 percent in ponderosa pine forest during this
timeframe. Ganey and Vojta (2010) attributed drought and subsequent
insect (bark beetle) infestation to the die-offs in trees. Drought
stress and a subsequent high degree of tree mortality from bark beetles
make high-elevation forests more susceptible to high-intensity
wildfires.
Climate is a top-down factor that synchronizes with fuel loads, a
bottom-up factor. Combined with a predicted reduction in snowpack and
an earlier snowmelt, these factors suggest wildfires will be larger,
more frequent, and more severe in the southwestern United States
(Ful[eacute] 2010, entire). Wildfires are expected to reduce vegetative
cover and result in greater soil erosion, subsequently resulting in
increased sediment flows in streams (Ful[eacute] 2010, entire).
Increased sedimentation in streams reduces the visibility of
gartersnakes in the water column, hampering their hunting ability as
well as resulting in fish kills (which is also caused by the disruption
in the nitrogen cycle post-wildfire), which reduce the amount of prey
available to gartersnake populations. Additionally, unnaturally high
amounts of sediment fill in pools in intermittent streams,

[[Page 38712]]

which reduces the amount and availability of habitat for fish and
amphibian prey.
In 2011 and 2012, both Arizona (2011 Wallow Fire) and New Mexico
(2012 Whitewater-Baldy Complex Fire) experienced the largest wildfires
in their respective State histories; indicative of the last decade that
has been punctuated by wildfires of massive proportion. The 2011 Wallow
Fire affected (to various degrees) approximately 540,000 acres (218,530
ha) of Apache-Sitgreaves National Forest, White Mountain Apache Indian
Tribe, and San Carlos Apache Indian Reservation lands in Apache,
Navajo, Graham, and Greenlee counties in Arizona as well as Catron
County, New Mexico (InciWeb 2011). The 2011 Wallow Fire impacted 97
percent of perennial streams in the Black River subbasin, 70 percent of
perennial streams in the Gila River subbasin, and 78 percent of the San
Francisco River subbasin and resulted in confirmed fish kills in each
subbasin (Meyer 2011, p. 3, Table 1); each of these streams is known to
support populations of either northern Mexican or narrow-headed
gartersnakes.
Although the Black River drainage received no moderate or high-
severity burns as a result of the 2011 Wallow Fire, the Fish and Snake
Creek subbasins (tributaries to the Black River) were severely burned
(Coleman 2011, p. 2). Post-fire fisheries surveys above Wildcat Point
in the Black River found no fish in a reach extending up to the
confluence with the West Fork of the Black River. This was likely due
to subsequent ash and sediment flows that had occurred there (Coleman
2011, p. 2). Fisheries surveys of the Black River in 2012 also
reflected a largely absent prey base for narrow-headed gartersnakes
(narrow-headed gartersnakes observed appeared to be in starving
condition), but young-of-the-year native fish were detected, which may
signal the beginning of fish recruitment (Lopez et al. 2012, entire).
Post-fire fisheries surveys at ``the Box,'' in the Blue River, detected
only a single native fish. This was also likely due to ash and sediment
flows and the associated subsequent fish kills that had occurred there,
extending down to the Gila River Box in Safford, Arizona (Coleman 2011,
pp. 2-3). The East Fork Black River subbasin experienced moderate to
high-severity burns in 23 percent of its total acreage that resulted in
declines in Apache trout and native sucker populations, but speckled
dace and brown trout remained prevalent as of 2011 (Coleman 2011, p.
3). These fire data suggest that the persistence of the prey base for
northern Mexican and narrow-headed gartersnakes in the Black River, and
narrow-headed gartersnakes in the lower Blue River, will be precarious
into the near- to mid-term future, as will likely be the stability of
gartersnake populations there. Immediate post-fire fish sampling in
Eagle Creek confirmed that fish populations had been severely depleted,
but that some level of population rebound had occurred by 2 years post-
fire (Marsh 2013, pers. comm.).
Several large wildfires have occurred historically on the Gila
National Forest. These fires have resulted in excessive sedimentation
of streams and affected resident fish populations that serve as prey
for narrow-headed gartersnakes. From 1989-2004, numerous wildfires
cumulatively burned much of the uplands within the Gila National
Forest, which resulted in most perennial streams in the area
experiencing ash flows and elevated sedimentation (Paroz et al. 2006,
p. 55). More recently, the 2012 Whitewater-Baldy Complex Fire in the
Gila National Forest in New Mexico is the largest wildfire in that
State's history. This wildfire was active for more than 5 weeks and
consumed approximately 300,000 acres (121,406 ha) of ponderosa, mixed-
conifer, pinyon-juniper, and grassland habitat (InciWeb 2012). Over 25
percent of the burn area experienced high-moderate burn severity
(InciWeb 2012) and included several subbasins occupied by narrow-headed
gartersnakes such as the Middle Fork Gila River, West Fork Gila River,
Iron Creek, the San Francisco River, Whitewater Creek, Turkey Creek,
and Mineral Creek (Brooks 2012, Table 1; Hellekson 2013, pers. comm.).
Other extant populations of the narrow-headed gartersnake in Gilita and
South Fork Negrito Creeks are also expected to be impacted from the
2012 Whitewater-Baldy Complex Fire. Narrow-headed gartersnake
populations in the Middle Fork Gila River and Whitewater Creek formerly
represented two of the four most robust populations known from New
Mexico, and two of the five known rangewide, and are expected to have
been severely jeopardized by post-fire effects to their prey base.
Thus, we now consider them currently as likely not viable, at least
until the watershed stabilizes and again supports a fish community, or
perhaps the next 5-10 years. In reference to Gila trout populations,
Brooks (2012, p. 3) stated that fish populations are expected to be
severely impacted in the West Fork Gila River and Whitewater Creek. The
loss of fish communities in affected streams is likely to lead to
associated declines, or potential extirpations, in affected narrow-
headed gartersnake populations as a result of the collapse in their
prey base.
Since 2000, several wildfires have affected occupied narrow-headed
gartersnake habitat on the Gila National Forest. The West Fork Gila
subbasin was affected by the 2002 Cub Fire, the 2003 Dry Lakes Fire,
and the 2011 Miller Fire; each resulted in post-fire ash and sediment
flows, which adversely affected fish populations used by narrow-headed
gartersnakes (Hellekson 2012a, pers. comm.). In 2011, the Miller Fire
significantly affected the Little Creek subbasin and has resulted in
substantive declines in abundance of the fish community (Hellekson
2012a, pers. comm.). Dry Blue and Campbell Blue creeks were affected by
the 2011 Wallow Fire (Hellekson 2012a, pers. comm.). Saliz Creek was
highly affected by the 2006 Martinez Fire (Hellekson 2012a, pers.
comm.). Turkey Creek was heavily impacted by the Dry Lakes Fire in
2003, which resulted in an extensive fish kill, but the fish community
has since rebounded (Hellekson 2012a, pers. comm.). It is not certain
how long the fish community was depleted or absent from Turkey Creek,
but it is suspected that the narrow-headed gartersnake population there
may have suffered declines from the loss of their prey base, as
evidenced by the current low population numbers. Black Canyon was
affected by large ash and debris flows from the 2013 Silver Fire (USFS
2013, entire). Prior to the 2002 Dry Lakes Fire, Turkey Creek was
largely populated by nonnative, predatory fish species, in its lower
reaches. Upper reaches were largely dominated by native fish species,
which have since rebounded in numbers (Hellekson 2012a, pers. comm.),
and may provide high-quality habitat for narrow-headed gartersnakes,
once the subbasin has adequately stabilized.
Effects to northern Mexican and narrow-headed gartersnake habitat
from wildfire should be considered in light of effects to the
structural habitat and effects to the prey base. Post-fire effects vary
with burn severity, percent of area burned within each severity
category, and the intensity and duration of precipitation events that
follow (Coleman 2011, p. 4). Low-severity burns within riparian habitat
can actually have a rejuvenating effect by removing decadent ground
cover and providing nutrients to remaining vegetation. As a result,
riparian vegetative communities may be more resilient to wildfire,
given that water is present (Coleman 2011, p. 4). Willows, an important
component to narrow-headed gartersnake habitat, can be

[[Page 38713]]

positively affected by low-severity burns, as long as the root crowns
are not damaged (Coleman 2011, p. 4). High-severity burns that occur
within the floodplain of occupied habitat are expected to have some
level of shorter term effect on resident gartersnake populations
through effects to the vegetative structure and abundance, which may
include a reduction of basking sites and a loss of cover, which could
increase the risk of predation. These potential effects need further
study. Post-fire ash flows, flooding, and impacts to native prey
populations are longer term effects and can occur for many years after
a large wildfire (Coleman 2011, p. 2).
Post-fire flooding with significant ash and sediment loads can
result in significant declines, or even the collapse, of resident fish
communities, which poses significant concern for the persistence of
resident gartersnake populations in affected areas. Sedimentation can
adversely affect fish populations used as prey by northern Mexican or
narrow-headed gartersnakes by: (1) Interfering with respiration; (2)
reducing the effectiveness of fish's visually based hunting behaviors;
and (3) filling in interstitial spaces (spaces between cobbles, etc.,
on the stream floor) of the substrate, which reduces reproduction and
foraging success of fish (Wheeler et al. 2005, p. 145). Excessive
sediment also fills in intermittent pools required for amphibian prey
reproduction and foraging. Siltation of the rocky interstitial spaces
along stream bottoms decreases the dissolved oxygen content where fish
lay their eggs, resulting in depressed recruitment of fish and a
subsequent reduction in prey abundance for northern Mexican and narrow-
headed gartersnakes through the loss of prey microhabitat (Nowak and
Santana-Bendix 2002, pp. 37-38). As stated above, sediment can lead to
several effects in resident fish species used by northern Mexican or
narrow-headed gartersnakes as prey, which can ultimately cause
increased direct fatalities, reduced reproductive success, lower
overall abundance, and reductions in prey species composition as
documented by Wheeler et al. (2005, p. 145). The underwater foraging
ability of narrow-headed gartersnakes (de Queiroz 2003, p. 381) and
likely northern Mexican gartersnakes is largely based on vision and is
also directly compromised by excessive turbidity caused by
sedimentation of water bodies. Suspended sediment in the water column
may reduce the narrow-headed gartersnake's visual hunting efficiency
from effects to water clarity, based on research conducted by de
Queiroz (2003, p. 381) that concluded the species relied heavily on
visual cues during underwater striking behaviors.
The presence of adequate interstitial spaces along stream floors
may be particularly important for narrow-headed gartersnakes. Hibbitts
et al. (2009, p. 464) reported the precipitous decline of narrow-headed
gartersnakes in a formerly robust population in the San Francisco River
at San Francisco Hot Springs from 1996 to 2004. The exact cause for
this decline is uncertain, but the investigators suspected that a
reduction in interstitial spaces along the stream floor from an
apparent conglomerate, cementation process may have affected the
narrow-headed gartersnake's ability to successfully anchor themselves
to the stream bottom when seeking refuge or foraging for fish (Hibbitts
et al. 2009, p. 464). These circumstances would likely result in low
predation success and eventually starvation. Other areas where
sedimentation has affected either northern Mexican or narrow-headed
gartersnake habitat are Cibecue Creek in Arizona, and the San Francisco
River and South Fork Negrito Creek in New Mexico (Rosen and Schwalbe
1988, p. 46; Arizona Department of Water Resources 2011, p. 1;
Hellekson 2012a, pers. comm.). The San Francisco River in Arizona was
classified as impaired due to excessive sediment from its headwaters
downstream to the Arizona-New Mexico border (Arizona Department of
Water Resources 2011, p. 1). South Fork Negrito Creek is also listed as
impaired due to excessive turbidity (Hellekson 2012a, pers. comm.).
Potential mechanisms exist that can ameliorate the effects of
wildfires, such as prescribed fire, use of wildland fire, fuels
management, and timber harvest, and can sustain desired conditions for
fire-adapted ecosystems and provide habitat for threatened and
endangered species, but will only be effective at a landscape scale.
The Guidance for Implementation of Federal Wildland Fire Management
Policy is the Department of Agriculture's single cohesive Federal fire
policy, and it was updated in February 2009. The intent of this policy
is to solidify that the full range of strategic and tactical options
are available and considered in the response to every wildland fire
(USFS 2013, entire). Benefits are considered to include the movement of
vegetation toward desired conditions, a greater contribution to
landscape restoration, control of invasive species, a reduction in
uncharacteristic wildfire across the broader landscape, and the
resiliency of potential natural vegetation types to adapt to climate
change (USFS 2013, entire). We are uncertain whether such projects can
be completed with the scope and urgency required to reverse the current
trend of massive, high-intensity wildfires in the southwest but intend
to facilitate their implementation as project cooperators. We conclude
that effects of high-intensity wildfires are threatening narrow-headed
gartersnakes with increasing likelihood of future impacts as a result
of climate change.
Summary
The presence of water is critical to both northern Mexican and
narrow-headed gartersnakes and their primary prey species because their
ecology and natural histories are strongly linked to water. Several
factors, both natural and manmade, contribute to the continued
degradation and dewatering of aquatic habitat throughout the range of
northern Mexican and narrow-headed gartersnakes. Increasing human
population growth is driving higher and higher demands for water in
both the United States and Mexico. Water is subsequently secured
through dams, diversions, flood-control projects, and groundwater
pumping, which affects gartersnake habitat through reductions in flow
and complete dewatering of stream reaches. Entire reaches of the Gila,
Salt, Santa Cruz, and San Francisco Rivers, as well as numerous other
rivers throughout the Mexican Plateau in Mexico that were historically
occupied by either or both northern Mexican or narrow-headed
gartersnakes, are now completely dry due to diversions, dams, and
groundwater pumping. Several groundwater basins within the range of
northern Mexican and narrow-headed gartersnakes in the United States
are considered active management areas where pumping exceeds recharge,
which is a constant threat to surface flow in streams and rivers
connected to these aquifers. Reduced flows concentrate northern Mexican
and narrow-headed gartersnakes and their prey with harmful nonnative
species, which accelerate and amplify adverse effects of native-
nonnative community interactions. Where surface water persists,
increasing land development and recreation use adjacent to and within
riparian habitat has led to further reductions in stream flow, removal
or alteration of vegetation, and increased frequency of adverse human
interactions with gartersnakes.
Exacerbating the effects of increasing human populations and higher
water demands, climate change predictions

[[Page 38714]]

include increased aridity, lower annual precipitation totals, lower
snow pack levels, higher variability in flows (lower low-flows and
higher high-flows), and enhanced stress on ponderosa pine communities
in the southwestern United States and northern Mexico. Increased stress
to ponderosa pine forests places them at higher risk of high-intensity
wildfires, the effects of which are discussed below. Climate change has
also been predicted to enhance the abundance and distribution of
harmful nonnative species, which adversely affect northern Mexican and
narrow-headed gartersnakes.
Cienegas, a unique and important habitat for northern Mexican
gartersnakes, have been adversely affected or eliminated by a variety
of historical and current land uses in the United States and Mexico,
including streambed modification, intensive livestock grazing,
woodcutting, artificial drainage structures, stream flow stabilization
by upstream dams, channelization, and stream flow reduction from
groundwater pumping and water diversions. The historical loss of the
cienega habitat of the northern Mexican gartersnake has resulted in
local population declines or extirpations, negatively affecting its
status and contributing to its decline rangewide.
Wildfire has historically been a natural and important disturbance
factor within the range of northern Mexican and narrow-headed
gartersnakes. However, in recent decades, forest management policies in
the United States have favored fire suppression, the result of which
has led to wildfires of unusual proportions, particularly along the
Mogollon Rim of Arizona and New Mexico. These policies are generally
not in place in Mexico, and consequently, wildfire is not viewed as a
significant threat to the northern Mexican gartersnake in Mexico.
However, in the last 2 years, both Arizona (2011 Wallow Fire) and New
Mexico (2012 Whitewater-Baldy Complex Fire) have experienced the
largest wildfires in their respective State histories, which is
indicative of the last decade having been punctuated by wildfires of
significant magnitude. High-intensity wildfire has been shown to result
in significant ash and sediment flows into habitat occupied by northern
Mexican or narrow-headed gartersnakes, resulting in significant
reductions of their fish prey base and, in some instances, total fish
kills. The interstitial spaces between rocks located along the stream
floor are important habitat for the narrow-headed gartersnake because
of its specialized foraging strategy and specialized diet. These spaces
are also important spawning and egg deposition habitat for native fish
species used as prey by narrow-headed gartersnakes. When these spaces
fill in with sediment, the narrow-headed gartersnake may be unable to
forage successfully and may succumb to stress created by a depressed
prey base.
A significant reduction or absence of a prey base results in stress
of resident gartersnake populations and can result in local population
extirpations. Also, narrow-headed gartersnakes are believed to rely
heavily on visual cues while foraging underwater; increased turbidity
from suspended fine sediment in the water column is likely to impede
their ability to use visual cues at some level. Factors that result in
depressed foraging ability from excessive sedimentation are likely to
be enhanced when effects from harmful nonnative species are also acting
on resident northern Mexican and narrow-headed gartersnake populations.
We consider the narrow-headed gartersnake to be particularly threatened
by the effects of wildfires as described because they occur throughout
its range, the species is a fish-eating specialist that is unusually
vulnerable to localized fish kills, and wildfire has already
significantly affected two of the last remaining five populations that
were formerly considered viable, pre-fire. We have demonstrated that
high-intensity wildfires have the potential to eliminate gartersnake
populations through a reduction or loss of their prey base. Since 1970,
wildfires have adversely impacted the native fish prey base in 6
percent of the historical distribution of northern Mexican gartersnakes
in the United States and 21 percent of that for narrow-headed
gartersnakes rangewide, according to GIS analysis. These percentages
represent only stream miles within fire perimeters, not downstream
effects of ash flows within drainages, which would undoubtedly increase
the percentage of habitat impacted, at least for narrow-headed
gartersnakes, whose distribution overlaps more concisely with more and
larger wildfires over recent decades.
All of these conditions affect the primary drivers of gartersnake
habitat suitability (the presence of water and prey) and exist in
various degrees throughout the range of both gartersnake species.
Collectively, they reduce the amount and arrangement of physically
suitable habitat for northern Mexican and narrow-headed gartersnakes
over their regional landscapes. The genetic representation of each
species is threatened when populations become disconnected and isolated
from neighboring populations because the length or area of dewatered
zones is too great for dispersing individuals to overcome. Therefore,
normal colonizing mechanisms that would otherwise reestablish
populations where they have become extirpated are no longer viable.
This subsequently leads to a reduction in species redundancy when
isolated, small populations are at increased vulnerability to the
effects of stochastic events, without a means for natural
recolonization. Ultimately, the effects of scattered, small, and
disjunct populations, without the means to naturally recolonize, is
weakened species resiliency as a whole, which ultimately enhances the
risk of either or both species becoming endangered or going extinct.
Therefore, based on the best available scientific and commercial
information, we conclude that land uses or conditions described above
that alter or dewater northern Mexican and narrow-headed gartersnake
habitat are threats rangewide, now and in the foreseeable future.

Other Cumulative and Synergistic Effect of Threats on Low-Density
Populations (Northern Mexican and Narrow-Headed Gartersnakes)

In most locations where northern Mexican or narrow-headed
gartersnakes historically occurred or still occur currently, two or
more threats are likely acting in combination with regard to their
influence on the suitability of those habitats or on the species
themselves. Many threats could be considered minor in isolation, but
when they affect gartersnake populations in combination with other
threats, become more serious. We have concluded that in as many as 24
of 29 known localities in the United States (83 percent), the northern
Mexican gartersnake population is likely not viable and may exist at
low population densities that could be threatened with extirpation or
may already be extirpated. We also determined that in as many as 29 of
38 known localities (76 percent), the narrow-headed gartersnake
population is likely not viable and may exist at low population
densities that could be threatened with extirpation or may already be
extirpated, but survey data are lacking in areas where access is
restricted. We have also discussed how harmful nonnative species have
affected recruitment of gartersnakes across their range. In viable
populations, gartersnakes are resilient to the loss of individuals
through ongoing recruitment into the reproductive age class. However,
when northern Mexican or narrow-headed gartersnakes occur at low
population densities in the absence

[[Page 38715]]

of appropriate recruitment, the loss of even a few adults could
substantially increase the risk of extirpation of local populations.
Below, we discuss threats that, when considered in combination, can
appreciably threaten low-density populations of these species with
extirpation.
Historical and Unmanaged Livestock Grazing and Agricultural Land Uses
(Northern Mexican and Narrow-Headed Gartersnake) (Factor A)
Currently in the United States, livestock grazing is a largely
managed activity, but in Mexico, livestock grazing is much less managed
or unmanaged altogether. Several examples of extant gartersnake
populations (in some cases, apparently robust populations) in Mexico
were found in habitat that was heavily grazed with no riparian
vegetation development; these sites were coincidently free or largely
free of harmful nonnative species (Burger 2007, entire). Historical
livestock grazing has damaged approximately 80 percent of stream,
cienega, and riparian ecosystems in the western United States (Kauffman
and Krueger 1984, pp. 433-435; Weltz and Wood 1986, pp. 367-368; Cheney
et al. 1990, pp. 5, 10; Waters 1995, pp. 22-24; Pearce et al. 1998, p.
307; Belsky et al. 1999, p. 1). Fleischner (1994, p. 629) found that
``Because livestock congregate in riparian ecosystems, which are among
the most biologically rich habitats in arid and semiarid regions, the
ecological costs of grazing are magnified at these sites.'' Stromberg
and Chew (2002, p. 198) and Trimble and Mendel (1995, p. 243) also
discussed the propensity for cattle to remain within or adjacent to
riparian communities. Expectedly, this behavior is more pronounced in
more arid regions (Trimble and Mendel 1995, p. 243). Effects from
historical or unmanaged grazing include: (1) Declines in the structural
richness of the vegetative community; (2) losses or reductions of the
prey base; (3) increased aridity of habitat; (4) loss of thermal cover
and protection from predators; (5) a rise in water temperatures to
levels lethal to larval stages of amphibian and fish development; and
(6) desertification (Szaro et al. 1985, p. 362; Schulz and Leininger
1990, p. 295; Schlesinger et al. 1990, p. 1043; Belsky et al. 1999, pp.
8-11; Zwartjes et al. 2008, pp. 21-23). In one rangeland study, it was
concluded that 81 percent of the vegetation that was consumed,
trampled, or otherwise removed was from a riparian area, which amounted
to only 2 percent of the total grazing space, and that these actions
were 5 to 30 times higher in riparian areas than on the uplands
(Trimble and Mendel 1995, pp. 243-244). However, according to one study
along the Agua Fria River, herbaceous ground cover can recover quickly
from heavy grazing pressure (Szaro and Pase 1983, p. 384). Additional
information on the effects of historical livestock grazing can be found
in Sartz and Tolsted (1974, p. 354); Rosen and Schwalbe (1988, pp. 32-
33, 47); Clary and Webster (1989, p. 1); Clary and Medin (1990, p. 1);
Orodho et al. (1990, p. 9); and Krueper et al. (2003, pp. 607, 613-
614).
Szaro et al. (1985, p. 360) assessed the effects of historical
livestock management on a related taxon and found that western
(terrestrial) gartersnake (Thamnophis elegans vagrans) populations were
significantly higher (versus controls) in terms of abundance and
biomass in areas that were excluded from grazing, where the streamside
vegetation remained lush, than where uncontrolled access to grazing was
permitted. This effect was complemented by higher amounts of cover from
organic debris from ungrazed shrubs that accumulate as the debris moves
downstream during flood events. Specifically, results indicated that
snake abundance and biomass were significantly higher in ungrazed
habitat, with a five-fold difference in number of snakes captured,
despite the difficulty of making observations in areas of increased
habitat complexity (Szaro et al. 1985, p. 360). Szaro et al. (1985, p.
362) also noted the importance of riparian vegetation for the
maintenance of an adequate prey base and as cover in thermoregulation
and predation avoidance behaviors, as well as for foraging success.
Direct fatalities of amphibian species, in all life stages, from being
trampled by livestock has been documented (Bartelt 1998, p. 96; Ross et
al. 1999, p. 163). Gartersnakes may, on occasion, be trampled by
livestock. A black-necked gartersnake (Thamnophis cyrtopsis cyrtopsis)
had apparently been killed by livestock trampling along the shore of a
stock tank in the Apache-Sitgreaves National Forest, within an actively
grazed allotment (Chapman 2005).
Subbasins where historical grazing has been documented as a
suspected contributing factor for either northern Mexican or narrow-
headed gartersnake declines include the Verde, Salt, Agua Fria, San
Pedro, Gila, and Santa Cruz (Hendrickson and Minckley 1984, pp. 140,
152, 160-162; Rosen and Schwalbe 1988, pp. 32-33; Girmendonk and Young
1997, p. 47; Hale 2001, pp. 32-34, 50, 56; Voeltz 2002, pp. 45-81;
Krueper et al. 2003, pp. 607, 613-614; Forest Guardians 2004, pp. 8-10;
Holycross et al. 2006, pp. 52-61; Paradzick et al. 2006, pp. 90-92;
USFS 2008). Livestock grazing still occurs in these subbasins but is a
largely managed land use and is not likely to pose significant threats
to either northern Mexican or narrow-headed gartersnakes where closely
managed. In cases where poor livestock management results in fence
lines in persistent disrepair, providing unmanaged livestock access to
occupied habitat, adverse effects from loss of vegetative cover may
result, most likely in the presence of harmful nonnative species. As we
described above, however, we strongly suspect that northern Mexican and
narrow-headed gartersnakes are somewhat resilient to physical habitat
disturbance where harmful nonnative species are absent.
The creation and maintenance of stock tanks is an important
component to livestock grazing in the southwestern United States. Stock
tanks associated with livestock grazing may facilitate the spread of
harmful nonnative species when they are intentionally or
unintentionally stocked by anglers and private landowners (Rosen et al.
2001, p. 24). The management of stock tanks is an important
consideration for northern Mexican gartersnakes in particular. Stock
tanks associated with livestock grazing can be intermediary ``stepping
stones'' in the dispersal of nonnative species from larger source
populations to new areas (Rosen et al. 2001, p. 24). The effects of
livestock grazing at stock tanks on northern Mexican gartersnakes
depend on how they are managed. Dense bank and aquatic vegetation is an
important habitat characteristic for the northern Mexican gartersnake
in the presence of harmful nonnative species. This vegetation can be
affected if the impoundment is poorly managed. When harmful nonnative
species are absent, the presence of bank line vegetation is less
important. Well-managed stock tanks provide important habitat for
northern Mexican gartersnakes and their prey base, especially when the
tank: (1) Remains devoid of harmful nonnative species while supporting
native prey species; (2) provides adequate vegetation cover; and (3)
provides reliable water sources in periods of prolonged drought. Given
these benefits of well-managed stock tanks, we believe well-managed
stock tanks are an important, even vital at this time, component to
northern Mexican gartersnake conservation and recovery.

[[Page 38716]]

Road Construction, Use, and Maintenance (Northern Mexican and Narrow-
Headed Gartersnake) (Factor A)
Roads can pose unique threats to herpetofauna, and specifically to
species like the northern Mexican gartersnake, its prey base, and the
habitat where it occurs. The narrow-headed gartersnake, alternatively,
is probably less affected by roads due to its more aquatic nature.
Roads fragment occupied habitat and can result in diminished genetic
variability in populations from increased fatality from vehicle strikes
and adverse human encounters as supported by current research on
eastern indigo snakes (Breininger et al. 2012, pp. 364-366). Roads
often track along streams and present a fatality risk to gartersnakes
seeking more upland, terrestrial habitat for brumation and gestation.
Roads may cumulatively impact both species through the following
mechanisms: (1) Fragmentation, modification, and destruction of
habitat; (2) increase in genetic isolation; (3) alteration of movement
patterns and behaviors; (4) facilitation of the spread of nonnative
species via human vectors; (5) an increase in recreational access and
the likelihood of subsequent, decentralized urbanization; (6)
interference with or inhibition of reproduction; (7) contributions of
pollutants to riparian and aquatic communities; (8) reduction of prey
communities; and (9) acting as population sinks (when population death
rates from vehicle strikes exceed birth rates in a given area) (Rosen
and Lowe 1994, pp. 146-148; Waters 1995, p. 42; Foreman and Alexander
1998, p. 220; Trombulak and Frissell 2000, pp. 19-26; Carr and Fahrig
2001, pp. 1074-1076; Hels and Buchwald 2001, p. 331; Smith and Dodd
2003, pp. 134-138; Angermeier et al. 2004, pp. 19-24; Shine et al.
2004, pp. 9, 17-19; Andrews and Gibbons 2005, pp. 777-781; Wheeler et
al. 2005, pp. 145, 148-149; Roe et al. 2006, p. 161; Sacco 2007, pers.
comm.; Ouren et al. 2007, pp. 6-7, 11, 16, 20-21; Jones et al. 2011,
pp. 65-66; Hellekson 2012a, pers. comm.).
Perhaps the most common factor in road fatality of snakes is the
propensity for drivers to unintentionally and intentionally run them
over, both because people often dislike snakes (Rosen and Schwalbe
1988, p. 43; Ernst and Zug 1996, p. 75; Green 1997, pp. 285-286; Nowak
and Santana-Bendix 2002, p. 39) and because they can be difficult to
avoid when crossing roads at perpendicular angles (Klauber 1956, p.
1026; Langley et al. 1989, p. 47; Shine et al. 2004, p. 11). Fatality
data for northern Mexican gartersnakes have been collected at the
Bubbling Ponds Hatchery since 2006. Of the 15 dead specimens, 8 were
struck by vehicles on roads within or adjacent to the hatchery ponds,
perhaps while crossing between ponds to forage (Boyarski 2011, pp. 1-
3). Van Devender and Lowe (1977, p. 47), however, observed several
northern Mexican gartersnakes crossing the road at night after the
commencement of the summer monsoon (rainy season), which highlights the
seasonal variability in surface activity of this snake. Wallace et al.
(2008, pp. 243-244) documented a vehicle-related fatality of a northern
Mexican gartersnake on Arizona State Route 188 near Tonto Creek that
occurred in 1995.
Adverse Human Interactions With Gartersnakes (Northern Mexican and
Narrow-Headed Gartersnake) (Factor E)
A fear of snakes is generally and universally embedded in modern
culture and is prevalent in the United States (Rosen and Schwalbe 1988,
p. 43; Ernst and Zug 1996, p. 75; Green 1997, pp. 285-286; Nowak and
Santana-Bendix 2002, p. 39). We use the phrase ``adverse human
interaction'' to refer to the act of humans directly injuring or
killing snakes out of a sense of fear or anxiety (ophidiophobia), or
for no apparent purpose. One reason the narrow-headed gartersnake is
vulnerable to adverse human interactions is because of its appearance.
The narrow-headed gartersnake is often confused for a venomous water
moccasin (cottonmouth, Agkistrodon piscivorus), because of its
triangular-shaped head and propensity to be found in or near water
(Nowak and Santana-Bendix 2002, p. 38). Although the nearest water
moccasin populations are located over 700 miles (1,127 km) to the east
in central Texas, these misidentifications prove fatal for narrow-
headed gartersnakes (Nowak and Santana-Bendix 2002, p. 38).
Adverse human interaction may be largely responsible for highly
localized extirpations in narrow-headed gartersnakes based on the
collection history of the species at Slide Rock State Park along Oak
Creek, where high recreation use is strongly suspected to result in
direct fatality of snakes by humans (Nowak and Santana-Bendix 2002, pp.
21, 38). Declines in narrow-headed gartersnake populations in the North
and East Forks of the White River have also been attributed to humans
killing snakes (Rosen and Schwalbe 1988, pp. 43-44). Locations in New
Mexico where this unnatural form of fatality has been observed include
Wall Lake (Fleharty 1967, p. 219) and Whitewater Creek (Hellekson
2012a, pers. comm.). Areas with high visitation and recreation levels,
where this type of fatality is most likely to be more common, include
the Middle Fork and mainstem of the Gila River within 1 mile of Cliff
Dwellings to Little Creek, from the confluence with the East Fork to
Little Creek and the reach from Turkey Creek to the Gila Bird Area
south of Highway 180 (Hellekson 2013, pers. comm.), in Whitewater Creek
from the Catwalk to Glenwood (Hellekson 2012a, pers. comm.), near San
Francisco Hot Springs along the San Francisco River (Hibbitts and
Fitzgerald 2009, p. 466), the San Francisco River ``Box'', Black Canyon
near the FR150 crossing, and the south Fork Negrito Creek (Hellekson
2013, pers. comm.).
Environmental Contaminants (Northern Mexican and Narrow-Headed
Gartersnake) (Factor A)
Environmental contaminants, such as heavy metals, may be common at
low background levels in soils and, as a result, concentrations are
known to bioaccumulate in food chains. A bioaccumulative substance
increases in concentration in an organism or in the food chain over
time. A mid- to higher-order predator, such as a gartersnake, may,
therefore, accumulate these types of contaminants over time in their
fatty tissues, which may lead to adverse health effects (Wylie et al.
2009, p. 583, Table 5). Campbell et al. (2005, pp. 241-243) found that
metal concentrations accumulated in the northern watersnake (Nerodia
sipedon) at levels six times that of their primary prey item, the
central stoneroller (a fish, Campostoma anomalum). Metals, in trace
amounts, can be sequestered in the skin of snakes (Burger 1992, p.
212), interfere with metabolic rates of snakes (Hopkins et al. 1999, p.
1261), affect the structure and function of their liver and kidneys,
and may also act as neurotoxins, affecting nervous system function
(Rainwater et al. 2005, p. 670). Burger (1992, p. 209) found higher
concentrations of mercury, lead, and chromium in the skin of snakes, as
opposed to whole body tissue, ``suggesting that frequent shedding of
skin can act as a method of toxic excretion by snakes.'' Drewett et al.
(2013, entire) studied mercury accumulation in 4 species of snakes
(including the common gartersnake) ranging from mostly aquatic to
mostly terrestrial in an attempt to ascertain if a snake's ecology
affected the risk of exposure and tissue accumulation levels. They
found that the more aquatic the species' ecology and prey base, the
higher risk for exposure and accumulation of mercury (Drewett et al.
2013, pp. 7-8).

[[Page 38717]]

Based on data collected in 2002-2010, mercury appears to be
bioaccumulating in fish found in the lower reaches of Tonto Creek,
where northern Mexican gartersnakes also occur (Rector 2010, pers.
comm.; Arizona Department of Environmental Quality (ADEQ) 2011, Table
1). In fact, the State record for the highest mercury concentrations in
fish tissue was reported in Tonto Creek from this investigation by
Rector (2010, pers. comm.). Mean mercury levels in fish were found to
range from 0.2-1.5 mg/kg. The mean mercury concentration for all fish
was 1.1 mg/kg (ADEQ 2011, p. 3). Due to the risks of adverse human
health effects, ADEQ (2011, p. 8) recommends that smallmouth bass,
green sunfish, and black bullheads caught from Tonto Creek not be
consumed, and common carp be consumed sparingly. Because gartersnakes
eat fish, mercury may be bioaccumulating in resident populations,
although no testing of gartersnakes has occurred.
Specific land uses such as mining and smelting, as well as road
construction and use, can be significant sources of contaminants in
air, water, or soil through point-source and non-point source
mechanisms. Copper mining has occurred in Arizona and adjacent Mexico
for centuries, and many of these sites have smelters (now
decommissioned), which are former sources of airborne contaminants.
Industrial mine sites occur in several counties in Arizona (Greenlee,
Pima, Pinal, Yavapai, and Gila), as well as in Grant County, New
Mexico. The current price of copper is high and is expected to continue
to increase into the next several decades, fueled by international
development and economic growth. Overall, 18 mines are either in
production or in the pre-production phases of development in Arizona
and New Mexico. The mining industry in Mexico is largely concentrated
in the northern tier of that country, with the State of Sonora being
the leading producer of copper, gold, graphite, molybdenum, and
wollastonite, as well as the leader among Mexican States with regard to
the amount of surface area dedicated to mining (Stoleson et al. 2005,
p. 56). The three largest mines in Mexico (all copper) are found in
Sonora (Stoleson et al. 2005, p. 57). One of these, the Cananea Copper
Mine adjacent to the Upper San Pedro River in northern Sonora, was
responsible for a massive spill event. For two consecutive years (1977-
1978), two leaching ponds overflowed into the San Pedro River resulting
in very acidic water conditions and high levels of heavy metals such as
copper, zinc, and manganese (Eberhardt 1981, pp. 1, 16). These releases
caused the death of all aquatic organisms in the San Pedro River for a
60-mile (97-km) reach downstream of the mine (Eberhardt 1981, pp. 1,
16).
The sizes of mines in Sonora vary considerably, as do the known
environmental effects from mining-related activities (from exploration
to long after closure), which include contamination and drawdown of
groundwater aquifers, erosion, acid mine drainage, fugitive dust,
pollution from smelter emissions, and landscape clearing (Stoleson et
al. 2005, p. 57). We are aware of no specific research on potential
effects of mining or environmental contaminants acting on northern
Mexican gartersnakes, but conclude, based on the best available
scientific and commercial information, that where this land use is
prevalent, contaminants may be a concern for resident gartersnakes or
their prey.
Northern Mexican Gartersnake Competition With Marcy's Checkered
Gartersnake (Northern Mexican Gartersnake) (Factor E)
Preliminary research suggests that Marcy's checkered gartersnake
(Thamnophis marcianus marcianus) may impact the future conservation of
the northern Mexican gartersnake in southern Arizona. Rosen and
Schwalbe (1988, p. 31) hypothesized that bullfrogs are more likely to
eliminate northern Mexican gartersnakes when Marcy's checkered
gartersnakes are also present. Marcy's checkered gartersnake is a semi-
terrestrial species that is able to co-exist to some degree with
harmful nonnative predators. This might be due to its apparent ability
to forage in more terrestrial habitats, specifically during the
vulnerable juvenile size classes (Rosen and Schwalbe 1988, p. 31; Rosen
et al. 2001, pp. 9-10). In every age class, the northern Mexican
gartersnake forages in aquatic habitats where nonnative predatory fish,
bullfrogs, and crayfish are present, which increases not only the
encounter rate between predator and prey, but also the juvenile
fatality rate of the northern Mexican gartersnake, which negatively
affects recruitment. As northern Mexican gartersnake numbers decline
within a population, space becomes available for occupation by Marcy's
checkered gartersnakes. If competitive pressure between these two
species has existed over time, it is reasonable to conclude that
northern Mexican gartersnakes were successfully out-competing Marcy's
checkered gartersnake prior to the invasion of harmful nonnative
species. Therefore, Marcy's checkered gartersnake may simply be filling
the ecological void left by the decline of the northern Mexican
gartersnake. At a minimum, more research is needed to determine the
relationship between these two gartersnake species.
Fatality From Entanglement Hazards (Northern Mexican and Narrow-Headed
Gartersnake) (Factor E)
In addressing the effects of soil erosion associated with road
construction projects or post-fire remedial subbasin management,
erosion control materials placed on the ground surface are often used.
Examples of products used in erosion or sediment control include mulch
control netting, erosion control blankets, fiber rolls (wattles), and
reinforced silt fences (California Coastal Commission 2012, p. 1).
Erosion control is considered a best management practice for most soil-
disturbing activities, and is broadly required as mitigation across the
United States, in particular to avoid excess sedimentation of streams
and rivers. Rolled erosion control products, such as temporary erosion
control blankets and permanent turf reinforcement mats, are two methods
commonly used for these purposes (Barton and Kinkead 2005, p. 34).
These products use stitching or net-like mesh products to hold
absorbent media together. At a restoration site in South Carolina, 19
snakes (15 dead) representing 5 different species were found entangled
in the netting and had received severe lacerations in the process of
attempting to escape their entanglement (Barton and Kinkead 2005, p.
34). Stuart et al. (2001, pp. 162-164) also reported the threats of
net-like debris to snake species. Kapfer and Paloski (2011, p. 4)
reported at least 31 instances involving 6 different species of snake
(including the common gartersnake) in Wisconsin that had become
entangled in the netting used for either erosion control or as a
wildlife exclusion product. In their review, Kapfer and Paloski (2011,
p. 6) noted that 0.5-in.-by-0.5-in. mesh has the greatest likelihood of
entangling snakes.
Similar snake fatalities have not been documented in Arizona or New
Mexico, according to our files. However, given the broad usage of these
materials across the distribution of the northern Mexican and narrow-
headed gartersnakes, it is not unlikely that fatalities occur, but go
unreported. The likelihood of either gartersnake species becoming
entangled depends on the distance these erosion control materials are
used from water in occupied habitat and the density of potentially
affected populations. Because erosion control products are

[[Page 38718]]

usually used to prevent sedimentation of streams, there is a higher
likelihood for gartersnakes to become entangled. We encourage those who
use these materials in or near gartersnake habitat to take necessary
precautions and monitor their use as gartersnake fatalities could
occur.
Discarded fishing nets have also been documented as a source of
fatalities for northern Mexican gartersnakes in the area of Lake
Chapala, Jalisco, Mexico (Barrag[aacute]n-Ram[iacute]rez and Ascencio-
Arrayga 2013, p. 159). Netting or seining is not an authorized form of
recreational fishing for sport fish in Arizona or New Mexico, but the
practice is allowed in either state for the collection of live baitfish
(AGFD 2013a, p. 57; NMDGF 2013, p. 17). Arizona fishing regulations
authorize seining for baitfish only where the baitfish will be used and
specify that seining is not allowed in Coconino, Apache, Pima, and
Cochise Counties. In other areas, it is suspected that most seinng
activity occurs at sites dominated by warmwater sportfish, where these
gartersnakes are less likely to occur. We are not certain of the
frequency at which these techniques are used for such purposes in
either state, but we do not suspect that discarded nets or seines are
commonly left on-site where they could ensnarl resident gartersnakes.
However, this practice is used in Mexico as a primary means of
obtaining freshwater fish as a food source and may be more of a threat
to local northern Mexican gartersnake populations where this practice
occurs.
Disease and Parasites (Northern Mexican and Narrow-Headed Gartersnake)
(Factor C)
Our review of the scientific literature did not find evidence that
disease is a current factor contributing to the decline in northern
Mexican or narrow-headed gartersnakes. However, a recent wildlife
health bulletin announced the emergence of snake fungal disease (SFD)
within the eastern and midwestern portions of the United States
(Sleemen 2013, p. 1). SFD has now been diagnosed in several terrestrial
and aquatic snake genera including Nerodia, Coluber, Pantherophis,
Crotalus, Sistrurus, and Lampropeltis. Clinical signs of SFD include
scabs or crusty scales, subcutaneous nodules, abnormal molting, white
opaque cloudiness of the eyes, localized thickening or crusting of the
skin, skin ulcers, swelling of the face, or nodules in the deeper
tissues (Sleemen 2013, p. 1). While fatalities have been documented as
a result of SFD, population-level impacts have not, due to the cryptic
and solitary nature of snakes and the lack of long-term monitoring data
(Sleemen 2013, p. 1). So far, no evidence of SFD has been found in the
genus Thamnophis, but the documented occurrence of SFD in ecologically
similar, aquatic colubrids such as Nerodia is cause for concern.
Parasites, such as the common plerocercoid larvae of a
pseudophyllidean tapeworm (possibly Spirometra spp.), have been
observed in northern Mexican gartersnakes (Boyarski (2008b, pp. 5-6),
which may not be detrimental to the snake's health (Boyarski 2008b, p.
8). However, G[uacute]zman (2008, p. 102) first documented a Mexican
gartersnake fatality from a larval Eustrongylides sp. (endoparasitic
nematode), which ``raises the possibility that infection of Mexican
gartersnakes by Eustrongylides sp. larvae might cause fatality in some
wild populations,'' especially if those populations are under stress as
a result of the presence of other threats. Nowak et al. (2014, pp. 148-
149) reported the first observation of what appears as maternal
transmission of endoparasites, specifically of the genus (Macdonaldius
sp.). We found no substantive evidence that parasites represent a
significant threat to either gartersnake species.
Summary
We found numerous effects of livestock grazing that have resulted
in the historical degradation of riparian and aquatic communities that
have likely affected northern Mexican and narrow-headed gartersnakes.
Mismanaged or unmanaged grazing can have disproportionate effects to
riparian communities in arid ecosystems due to the attraction of
livestock to water, forage, and shade. We found current livestock
grazing activities to be more of a concern in Mexico, at least when it
occurs in areas that also support harmful nonnative species. The most
profound impacts from livestock grazing in the southwestern United
States occurred nearly 100 years ago, were significant, and may still
be affecting some areas that have yet to fully recover. Unmanaged or
poorly managed livestock operations likely have more pronounced effects
in areas impacted by harmful nonnative species through a reduction in
cover. However, land managers in Arizona and New Mexico currently
emphasize the protection of riparian and aquatic habitat in allotment
management planning, usually through fencing, rotation, monitoring, and
range improvements such as developing remote water sources.
Collectively, these measures have reduced the likelihood of significant
adverse impacts on northern Mexican or narrow-headed gartersnakes,
their habitat, and their prey base. We also recognize that, while the
presence of stock tanks on the landscape can benefit nonnative species,
well-managed stock tanks are currently an invaluable tool in the
conservation and recovery of northern Mexican gartersnakes and their
prey.
Other activities, factors, or conditions that act in combination,
such as road construction, use, and management, adverse human
interactions, environmental contaminants, entanglement hazards, and
competitive pressures from sympatric species, occur within the
distribution of these gartersnakes and have the propensity to
contribute to further population declines or extirpations where
gartersnakes occur at low population densities. An emerging skin
disease, SFD, has not yet been documented in gartersnakes but has
affected snakes of many genera within the United States, including
ecologically similar species, and may pose a future threat to northern
Mexican and narrow-headed gartersnakes. Where low-density populations
are affected by these types of threats described above, even the loss
of a few reproductive adults, especially females, from a population can
have significant population-level effects, most notably in the presence
of harmful nonnative species. Continued population declines and
extirpations threaten the genetic representation of each species
because many populations have become disconnected and isolated from
neighboring populations. This subsequently leads to a reduction in
species redundancy and resiliency when isolated, small populations are
at increased vulnerability to the effects of stochastic events, without
a means for natural recolonization. Based on the best available
scientific and commercial information, we conclude that these threats
have the tendency to act synergistically and disproportionately on low-
density gartersnake populations rangewide, now and in the foreseeable
future.

Adequacy and Effectiveness at Reducing Identified Threats of Existing
Regulatory Mechanisms (Northern Mexican and Narrow-Headed Gartersnake)
(Factors D and E)

Below, we examine whether existing regulatory mechanisms are
adequate to address the threats to the northern Mexican and narrow-
headed gartersnakes discussed under other factors and whether these
regulations are acting to alleviate the threats identified to the
species. Section 4(b)(1)(A) of the Endangered Species Act requires the
Service to take into account ``those efforts, if any, being

[[Page 38719]]

made by any State or foreign nation, or any political subdivision of a
State or foreign nation, to protect such species.'' We interpret this
language to require us to consider relevant Federal, State, and Tribal
laws, regulations, and other such mechanisms that may minimize any of
the threats we describe in the threats analysis under the other four
factors, or otherwise influence conservation of the species. We give
strongest weight to statutes and their implementing regulations, and
management direction that stems from those laws and regulations. They
are nondiscretionary and enforceable, and are considered a regulatory
mechanism under this analysis. Having evaluated the significance of the
threat as mitigated by any such conservation efforts, we analyze under
Factor D the extent to which existing regulatory mechanisms are
inadequate to address the specific threats to the species. Regulatory
mechanisms, if they exist, may reduce or eliminate the impacts from one
or more identified threats. In this section, we review existing State
and Federal regulatory mechanisms to determine whether they effectively
reduce or remove threats to the species.
A number of Federal statutes potentially afford protection to
northern Mexican and narrow-headed gartersnakes or their prey species.
These include section 404 of the Clean Water Act (33 U.S.C. 1251 et
seq.), Federal Land Policy and Management Act (43 U.S.C. 1701 et seq.),
National Forest Management Act (16 U.S.C. 1600 et seq.), National
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), and the Act.
However, in practice, these statutes have not been able to provide
sufficient protection to prevent the currently observed downward trend
in northern Mexican and narrow-headed gartersnakes or their prey
species, and the concurrent upward trend in threats.
Section 404 of the Clean Water Act regulates placement of fill into
waters of the United States, including the majority of northern Mexican
and narrow-headed gartersnake habitat. However, many actions with the
potential to be highly detrimental to both species, their prey base,
and their habitat, such as gravel mining and irrigation diversion
structure construction and maintenance, may be exempted from the Clean
Water Act. Other detrimental actions, such as bank stabilization and
road crossings, are covered under nationwide permits that receive
limited environmental review. A lack of thorough, site-specific
analyses for projects can allow substantial adverse effects to northern
Mexican or narrow-headed gartersnakes, their prey base, or their
habitat.
The majority of the extant populations of northern Mexican and
narrow-headed gartersnakes in the United States occur on lands managed
by the U.S. Bureau of Land Management (BLM) and U.S. Forest Service.
Both agencies have riparian protection goals that may provide habitat
benefits to both species; however, neither agency has specific
management plans for northern Mexican or narrow-headed gartersnakes. As
a result, some of the significant threats to these gartersnakes, for
example, those related to nonnative species, are not necessarily
addressed on these lands. The BLM considers the northern Mexican
gartersnake as a ``Sensitive Species'' by default, due to its status
under the Act (U.S. Bureau of Land Management (USBLM) 2010), and agency
biologists actively attempt to identify gartersnakes for their records
for snakes observed incidentally during fieldwork (Young 2005). BLM
policy (BLM Manual Section 6840) requires consideration of sensitive
species during planning of activities and projects and mitigation of
specific threats. The BLM's Resource Management Plans include
objectives and management actions to benefit riparian habitat and
native fish; with some addressing ``invasive wildlife species'' (USBLM
2013, p. 2). When the Agua Fria National Monument was created in
January 2000, lowland leopard frogs, native fish, northern Mexican
gartersnakes, and riparian habitat were designated as ``monument
objects'' under protection by the National Monument (USBLM 2013, p. 3).
Similar conservation provisions are in place on the BLM's National
Conservation Areas (NCAs), such as the Las Cienegas NCA, San Pedro
River NCA, and the Gila Box Riparian NCA. While these measures likely
minimize the effect of otherwise adverse regional land use activities
on the aquatic community, gartersnake populations in these areas remain
in a precarious status.
The U.S. Forest Service does not include northern Mexican or
narrow-headed gartersnakes on their Management Indicator Species List,
but both species are included on the Regional Forester's Sensitive
Species List (USFS 2007, pp. 38-39). This means they are considered in
land management decisions, and protective measures can be implemented
to minimize adverse effects of otherwise lawful activities. However we
found no examples of specific protective measures that have been
implemented for these species. Individual U.S. Forest Service
biologists who work within the range of either northern Mexican or
narrow-headed gartersnakes may opportunistically gather data for their
records on gartersnakes observed incidentally in the field or
coordinate with other collaborators on surveys, although it is not
required. The Gila National Forest mentions the narrow-headed
gartersnake in their land and resource management plan, which includes
standards relating to forest management for the benefit of endangered
and threatened species as identified through approved management and
recovery plans (Center for Biological Diversity (CBD) et al. 2011, p.
18). Neither species is mentioned in any other land and resource
management plan for the remaining national forests where they occur
(CBD et al. 2011, p. 18).
The New Mexico Department of Game and Fish lists the northern
Mexican gartersnake as State-endangered and the narrow-headed
gartersnake as State-threatened (NMDGF 2006, Appendix H). A species is
State-endangered if it is in jeopardy of extinction or extirpation
within the State; a species is State-threatened if it is likely to
become endangered within the foreseeable future throughout all or a
significant portion of its range in New Mexico (NMDGF 2006, p. 52).
``Take,'' defined as ``to harass, hunt, capture or kill any wildlife or
attempt to do so'' by New Mexico Statutes Annotated (NMSA) 17-2-38.L.,
is prohibited without a scientific collecting permit issued by the New
Mexico Department of Game and Fish as per NMSA 17-2-41.C and New Mexico
Administrative Code (NMAC) 19.33.6. However, while the New Mexico
Department of Game and Fish can issue monetary penalties for illegal
take of either northern Mexican gartersnakes or narrow-headed
gartersnakes, the same provisions are not in place for actions that
result in loss or modification of their habitats (NMSA 17-2-41.C and
NMAC 19.33.6) (Painter 2005).
Prior to 2005, the AGFD allowed for take of up to four northern
Mexican or narrow-headed gartersnakes per person per year as specified
in Commission Order 43. The AGFD defines ``take'' as ``pursuing,
shooting, hunting, fishing, trapping, killing, capturing, snaring, or
netting wildlife or the placing or using any net or other device or
trap in a manner that may result in the capturing or killing of
wildlife.'' The AGFD subsequently amended Commission Order 43,
effective January 2005. Take of northern Mexican and narrow-headed
gartersnakes is no longer permitted in Arizona without issuance of a
scientific

[[Page 38720]]

collecting permit (Ariz. Admin. Code R12-4-401 et seq.) or special
authorization. While the AGFD can seek criminal or civil penalties for
illegal take of these species, the same provisions are not in place for
actions that result in destruction or modification of the gartersnakes'
habitat. In addition to making the necessary regulatory changes to
promote the conservation of northern Mexican and narrow-headed
gartersnakes, the AGFD's Nongame Branch continues to be a strong
partner in research and survey efforts that further our understanding
of current populations, and assist with conservation efforts and the
establishment of long-term conservation partnerships.
Throughout Mexico, the Mexican gartersnake is listed at the species
level of its taxonomy as ``Amenazadas,'' or Threatened, by the
Secretaria de Medio Ambiente y Recursos Naturales (SEMARNAT) (SEDESOL
2010, p. 71). Threatened species are ``those species, or populations of
the same, likely to be in danger of disappearing in a short or medium
timeframe, if the factors that negatively impact their viability, cause
the deterioration or modification of their habitat or directly diminish
the size of their populations continue to operate'' (Secretar[iacute]a
de Desarrollo Social (SEDESOL) 2010, p. 5). This designation prohibits
taking of the species, unless specifically permitted, as well as
prohibits any activity that intentionally destroys or adversely
modifies its habitat. Additionally, in 1988, the Mexican Government
passed a regulation that is similar to the National Environmental
Policy Act of the United States. This Mexican regulation requires an
environmental assessment of private or government actions that may
affect wildlife or their habitat (SEDESOL 1988 Ley General del
Equilibrio Ecol[oacute]gico y la Protecci[oacute]n al Ambiente
(LGEEPA)).
The Mexican Federal agency known as the Instituto Nacional de
Ecolog[iacute]a (INE) is responsible for the analysis of the status and
threats that pertain to species that are proposed for listing in the
Norma Oficial Mexicana NOM-059 (the Mexican equivalent to an endangered
and threatened species list), and, if appropriate, the nomination of
species to the list. INE is generally considered the Mexican
counterpart to the United States' Fish and Wildlife Service. INE
developed the Method of Evaluation of the Risk of Extinction of the
Wild Species in Mexico (MER), which unifies the criteria of decisions
on the categories of risk and permits the use of specific information
fundamental to listing decisions. The MER is based on four independent,
quantitative criteria: (1) Size of the distribution of the taxon in
Mexico; (2) state (quality) of the habitat with respect to natural
development of the taxon; (3) intrinsic biological vulnerability of the
taxon; and (4) impacts of human activity on the taxon. INE began to use
the MER in 2006; therefore, all species previously listed in the NOM-
059 were based solely on expert review and opinion in many cases.
Specifically, until 2006, the listing process under INE consisted of a
panel of scientific experts who convened as necessary for the purpose
of defining and assessing the status and threats that affect Mexico's
native species that are considered to be at risk, and applying those
factors to the definitions of the various listing categories. In 1994,
when the Mexican gartersnake was placed on the NOM-059 (SEDESOL 1994
(NOM-059-ECOL-1994), p. 46) as a threatened species, the decision was
made by a panel of scientific experts.
Although the Mexican gartersnake is listed as a threatened species
in Mexico and based on our experience collaborating with Mexico on
trans-border conservation efforts, no recovery plan or other
conservation planning occurs because of this status, and enforcement of
the regulation protecting the gartersnake is sporadic, depending on
available resources and location. Based upon the best available
scientific and commercial information on the status of the species, and
the historic and continuing threats to its habitat in Mexico, our
analysis concludes that regulatory mechanisms enacted by the Mexican
Government to conserve the northern Mexican gartersnake are not
adequate to address threats to the species or its habitat.
In summary, we reviewed a number of existing regulations that
potentially address issues affecting the northern Mexican and narrow-
headed gartersnakes and their habitats. Mexican law prohibits take of
the northern Mexican gartersnake and the intentional destruction or
modification of northern Mexican gartersnake habitat. However that law
has not led to a reduction in threats such that they no longer meet the
definition of endangered or threatened under the Act. Furthermore, most
existing regulations in the United States within the range of northern
Mexican and narrow-headed gartersnakes were not specifically designed
to protect the gartersnakes or their habitats, which is the overarching
threat to the species. For example, Arizona and New Mexico both have
statutes designed for protection of state-listed species that prohibit
the direct collection of individuals. However neither state law is
designed to provide protection of habitat and ecosystems. Therefore,
these laws are not reducing threats to the species such that they no
longer meet the definition of endangered or threatened under the Act.

Current Conservation of Northern Mexican and Narrow-Headed Gartersnakes
(Factor E)

Several conservation measures implemented by land and resource
managers, private land owners, and other stakeholders can directly or
indirectly benefit populations of northern Mexican and narrow-headed
gartersnakes. For example, the AGFD's conservation and mitigation
program (CAMP; implemented under an existing section 7 incidental take
permit) has committed to either stocking (with captive-bred stock) or
securing two populations each of northern Mexican and narrow-headed
gartersnakes to help minimize adverse effects to these species from
their sport fish stocking program through 2021 (USFWS 2011, Appendix
C). Other CAMP commitments include: (1) Developing a gartersnake
monitoring, research, and restocking plan to guide CAMP activities to
establish or secure populations; (2) developing outreach material to
reduce the deliberate killing or injuring of gartersnakes (placed in
high angler access areas); (3) ensuring that chemically renovated
streams are quickly restocked with native fish as gartersnake prey; (4)
conducting a live bait assessment team to develop recommendations to
amend live bait management; (5) reviewing and updating outreach
programs on the risks to native aquatic species from the transport of
nonnative aquatic species; (6) developing and implementing a public
education program on gartersnakes; and (7) working with the New Mexico
Department of Game and Fish to examine the roll of escaped rainbow
trout from Luna Lake into tributaries to the San Francisco River in
supporting narrow-headed gartersnakes. The programs' management
strategy is encapsulated in AGFD (2014a, entire) and progress on
activities through June 2013 is reported in AGFD (2012c, pp. 26-30;
2013b, pp. 37-44).
Significant challenges will have to be met for creating or securing
two populations each of northern Mexican or narrow-headed gartersnakes.
Captive propagation, if used to create stock for reintroductions, has
only been possible for northern Mexican gartersnakes. Specifically,
after approximately 6 years of experimentation with captive propagation
at five institutions, using two colonies of northern Mexican

[[Page 38721]]

gartersnakes and three colonies of narrow-headed gartersnakes, success
has been limited (see Gartersnake Conservation Working Group (GCWG)
2007, 2008, 2009, 2010). In 2012 and 2013, approximately 60 northern
Mexican gartersnakes were produced at one institution, 40 of which were
subsequently marked and released along Cienega Creek. These were the
first gartersnakes of either species to be produced under this program,
but the current status of released individuals remains unknown. No
narrow-headed gartersnakes have been produced in captivity under this
program since its inception. Secondly, in order to have the greatest
chance for success, the process of ``securing'' a population of either
species will likely involve an aggressive nonnative removal strategy,
and will have to account for habitat connectivity to prevent reinvasion
of unwanted species. Therefore, securing a population of either species
may involve removal of harmful nonnatives from an entire subbasin or on
a landscape scale (Cotton et al. 2014, pp. 12-13). In situations where
harmful nonnatives do not pose a threat to a given population, other
types of recovery actions may suffice.
To protect habitat for candidate, threatened, and endangered
species, including northern Mexican gartersnakes in the Agua Fria
subbasin, the AGFD purchased the approximate 200-acre (81-ha) Horseshoe
Ranch along the Agua Fria River located near the Bloody Basin Road
crossing, east of Interstate 17 and southeast of Cordes Junction,
Arizona. The AGFD plans (presumably in the next 5-10 years) to
introduce northern Mexican gartersnakes, as well as lowland leopard
frogs and native fish species, into a large pond, protected by bullfrog
exclusion fencing, located adjacent to the Agua Fria River. The
bullfrog exclusion fencing around the pond will permit the dispersal of
northern Mexican gartersnakes and lowland leopard frogs from the pond,
allowing the pond to act as a source population to the Agua Fria River.
The AGFD's short- to mid-term conservation planning for Horseshoe Ranch
will help ensure the northern Mexican gartersnake persists in this
historical locality.
In 2007, the New Mexico Department of Game and Fish completed a
recovery plan for narrow-headed gartersnakes in New Mexico (Pierce
2007, pp. 13-15) that included the following management objectives: (1)
Researching the effect of known threats to, and natural history of, the
species; (2) acquiring funding sources for research, monitoring, and
management; (3) enhancing education and outreach; and (4) managing
against known threats to the species. Implementation of the recovery
plan was to occur between the second half of 2007 through 2011, and was
divided into three main categories: (1) Improve and maintain knowledge
of potential threats to the narrow-headed gartersnake; (2) improve and
maintain knowledge of the biology of the narrow-headed gartersnake; and
(3) develop and maintain high levels of cooperation and coordination
between stakeholders and interested parties (Pierce 2007, pp. 16-17).
Our review of the plan found that it lacked specific threat-mitigation
commitments on the landscape, as well as stakeholder accountability for
implementing activities prescribed in the plan. We also found that
actions calling for targeted nonnative species removal or management
were absent in the implementation schedule provided in Pierce (2007, p.
17). As we have discussed at length, harmful nonnative species are the
primary driver of continued declines in both gartersnake species. No
recovery plan, conservation plan, or conservation agreement currently
exists in New Mexico with regard to the northern Mexican gartersnake
(NMDGF 2006, Table 6-3).
In Arizona's State Wildlife Action Plan 2012-2022 (SWAP) (AGFD
2012b, Appendix E), both the northern Mexican and narrow-headed
gartersnake are Tier 1A Species of Greatest Conservation Need (SGCN).
SGCN include those ``species that each State identified as most in need
of conservation actions'' and Tier 1A species include ``those species
for which the Department has entered into an agreement or has legal or
other contractual obligations, or warrants the protection of a closed
season'' (AGFD 2012b, p. 16). The SWAP is not a regulatory document,
and does not provide any specific protections for either the
gartersnakes themselves, or their habitats. The AGFD does not have
specified or mandated recovery goals for either the northern Mexican or
narrow-headed gartersnake, nor has a conservation agreement or recovery
plan been developed for either species.
Indirect benefits for both gartersnake species occur through
recovery actions designed for their prey species. Since the Chiricahua
leopard frog was listed as threatened under the Act, significant
strides have been made in its recovery, and the mitigation of its known
threats. The northern Mexican gartersnake, in particular, has likely
benefitted from these actions, at least in some areas, such as at the
Las Cienegas Natural Conservation Area and in Scotia Canyon of the
Huachuca Mountains. However, much of the recovery of the Chiricahua
leopard frog has occurred in areas that have not directly benefitted
the northern Mexican gartersnake, either because these activities have
occurred outside the known distribution of the northern Mexican
gartersnake or because they have occurred in isolated lentic systems
that are far removed from large perennial streams that typically
provide source populations of northern Mexican gartersnakes. In recent
years, significant strides have been made in controlling bullfrogs on
local landscape levels in Arizona, such as in the Scotia Canyon area,
in the Las Cienegas National Conservation Area, on the BANWR, and in
the vicinity of Pena Blanca Lake in the Pajarito Mountains. Recent
efforts to return the Las Cienegas National Conservation Area to a
wholly native biological community have involved bullfrog eradication
efforts, as well as efforts to recover the Chiricahua leopard frog and
native fish species. These actions should assist in conserving the
northern Mexican gartersnake population in this area. Bullfrog control
has been shown to be most effective in simple, lentic systems such as
stock tanks. Therefore, we encourage livestock managers to work with
resource managers in the systematic eradication of bullfrogs from stock
tanks where they occur, or at a minimum, ensure they are never
introduced.
An emphasis on native fish recovery in fisheries management and
enhanced harmful nonnative species control to favor native communities
may be the single most efficient and effective manner to recover these
gartersnakes, in addition to appropriate management for all listed or
sensitive native fish and amphibian species upon which they prey.
Alternatively, resource management policies that are intended to
directly benefit or maintain harmful nonnative communities, and which
will likely exclude native species, will significantly reduce the
potential for the conservation and recovery of northern Mexican and
narrow-headed gartersnakes, in those areas where they overlap with
habitat occupied by either gartersnake.
Fisheries managers strive to balance the needs of the recreational
angling community against those required by native aquatic communities.
Fisheries management has direct implications for the conservation and
recovery of northern Mexican and narrow-headed gartersnakes in the
United States. Clarkson et al. (2005) discuss management conflicts as a
primary factor in the decline of native fish species in the
southwestern United States, and declare the entire native fish

[[Page 38722]]

fauna as imperiled. The investigators cite nonnative species as the
most consequential factor leading to rangewide declines of native fish,
and that such declines prevent or negate species' recovery efforts from
being implemented or being successful (Clarkson et al. 2005, p. 20).
Maintaining the status quo of current management of fisheries within
the southwestern United States will have serious adverse effects to
native fish species (Clarkson et al. 2005, p. 25), which will affect
the long-term viability of northern Mexican and narrow-headed
gartersnakes and their potential for recovery. Clarkson et al. (2005,
p. 20) also note that over 50 nonnative species have been introduced
into the Southwest as either sportfish or baitfish, and some are still
being actively stocked, managed for, and promoted by both Federal and
State agencies as nonnative recreational fisheries.
To help resolve the fundamental conflict of management between
native fish and recreational sport fisheries, Clarkson et al. (2005,
pp. 22-25) propose the designation of entire subbasins as having either
native or nonnative fisheries and manage for these goals aggressively.
The idea of watershed-segregated fisheries management is also supported
by Marsh and Pacey (2005, p. 62). As part of the AGFD's overall
wildlife conservation strategy, the AGFD has planned an integrated
fisheries management approach (AGFD 2012b, p. 106), which is apparently
designed to manage subbasins specifically for either nonnative or
native fish communities. This strategy is described in detail in AGFD
(2009, entire), but the AGFD has not yet initiated implementation of
this strategy or decided how fisheries will be managed in Arizona's
subbasins, and we are not aware of a specific implementation timeline.
However, the ``current fish assemblage,'' ``current recovery or
conservation category,'' and ``current angling category'' inform what
is referred to as Step 2c: Identification of Current Fishery Values''
(AGFD 2009, pp. 10-11). Factors such as angler access (which
contributes directly to angler use days (AUD)), existing fish
communities, and stream flow considerations are likely to inform such
broadly based decisions.
Due to the relative scarcity of perennial streams in arid regions
such as Arizona, several of Arizona's large perennial rivers present an
array of existing sport fishing opportunities and angler access points,
and already contain harmful nonnative fish species that are considered
sport fish. We anticipate that these rivers may be preferred as
nonnative fisheries under the watershed designation process. Another
significant and confounding factor is the AGFD's ``no net loss'' policy
that addresses sport fishery resources statewide. There is no official
written AGFD Commission guidance on ``no net loss'' according to AGFD
(2009, Appendix D), but ``Commission policy DOM [Arizona Game Fish
Department Operating Manual] A2.24, Wildlife Management Program Goal
and Objective 6 states, `provide and promote fishing
opportunities to sustain a minimum of 8,000,000 AUD per year by June
30, 1997.' Although this policy has yet to be revised by the
Commission, based on current data, we remain below 8,000,000 AUD's
statewide (AGFD 2009, Appendix D). As such, it was determined the
Department's goal to manage for no net loss is consistent with current
Commission policy (A2.24). The ``no net loss'' policy is a guiding
tenet, and its implementation is directed as follows (AGFD 2009,
Appendix D):

``When a sport fishery is valued less than a native aquatic
conservation value within a management unit, the loss of sport
fishing opportunity will be compensated for by gain of an equal
number of AUDs in another area or management unit. This opportunity
will be created within the same watershed when possible. For this
purpose, a watershed is defined as a six-digit-numbered area
referenced on the USGS's Hydrological Unit Map. If this is not
possible, the opportunity will be created within the same Department
regional boundaries. Again, if this is not possible, the opportunity
will be created somewhere within the State with extensive
coordination between regional staff. If a net loss cannot be
avoided, the Director will evaluate if the loss is acceptable by
gauging the input from the public process leading to the
recommendation and may take the information to the Commission at his
discretion. The replacement opportunity will be initiated no more
than two years following the loss to anglers.''

Extensive coordination between AGFD and the Service will be
required under the no net loss policy with regard to gartersnake
conservation and recovery because the amount of suitable riparian and
aquatic habitat is finite, yet, somehow, the existing opportunity for
AUD must be maintained. This increases the uncertainty for the
persistence of existing gartersnake populations in Arizona.
Large perennial rivers that serve as sport fisheries also currently
serve as important habitat for northern Mexican or narrow-headed
gartersnake. If designated for sportfishing, fisheries management of
these rivers would likely include the maintenance of predatory sport
fish species, which would likely diminish the recovery potential for
gartersnakes in these areas, and, perhaps, even result in the local
extirpations of populations of northern Mexican and narrow-headed
gartersnakes. Alternatively, subbasins that are targeted for wholly
native species assemblages would likely secure the persistence of
northern Mexican and narrow-headed gartersnakes that occur there, if
not result in their complete recovery in these areas. Specific
subbasins where targeted fisheries management is to occur were not
provided in AGFD (2012b), but depending on which areas are chosen for
each management emphasis, the potential for future conservation and
recovery of northern Mexican and narrow-headed gartersnakes could
either be significantly bolstered, or significantly hampered. Close
coordination with the AGFD on the delineation of fisheries management
priorities in Arizona's subbasins will be instrumental to ensuring that
conservation and recovery of northern Mexican and narrow-headed
gartersnakes can occur.
Conservation of these gartersnakes has been implemented in the
scientific and management communities as well. The AGFD recently
produced identification cards for distribution that provide information
to assist field professionals with the identification of each of
Arizona's five native gartersnake species, as well as guidance on
submitting photographic vouchers for university museum collections.
Arizona State University and the University of Arizona now accept
photographic vouchers in lieu of physical specimens, in their
respective museum collections. These measures appreciably reduce the
necessity for physical specimens (unless discovered postmortem) for
locality voucher purposes and, therefore, further reduce impacts to
vulnerable populations of northern Mexican or narrow-headed
gartersnakes.
Despite these collective conservation efforts we have described
above, northern Mexican and narrow-headed gartersnakes have continued
to decline throughout their ranges due to past, current, and future
threats that have not been addressed through conservation efforts.

Summary of Changes From the Proposed Rule

Based on information provided during the comment period by the
general public, tribes, states, and peer reviewers, we updated the
information contained in the proposed rule for incorporation into this
final rule. In addition, new references were obtained,

[[Page 38723]]

evaluated, and discussed in the deliberation of information in the
final rule that were either not available or not obtained during the
development of the proposed rule. For clarity, we also revised the
language used in our Findings for the listing rule and in the
background and regulatory language of the 4(d) rule. However, no
substantive changes were made to either the conclusion of the final
listing rule or the scope of the final 4(d) rule.

Summary of Comments and Recommendations

In the proposed rule published on July 10, 2013 (78 FR 41500), we
requested that all interested parties submit written comments on the
proposal by September 9, 2013. We also contacted appropriate Federal,
State, and Tribal agencies, scientific experts and organizations, and
other interested parties and invited them to comment on the proposal.
Newspaper notices inviting general public comment were published in the
Verde Valley Independent, Camp Verde Bugle, Arizona Daily Star, and the
Silver City Sun News. We received a request for a public hearing from
the Hereford Natural Resource Conservation District who later withdrew
their request.
Our summary responses to the substantive comments we received on
the proposed listing rules and proposed 4(d) rule are provided below.
Comments simply providing support for or opposition to the proposed
rule, without any supporting information, were not considered to be
substantive and we do not provide a response.

Peer Reviewer Comments

In accordance with our peer review policy published on July 1, 1994
(59 FR 34270), we solicited expert opinion from eight knowledgeable
individuals with scientific expertise that included familiarity with
northern Mexican and narrow-headed gartersnakes and their habitat,
biological needs, and threats. We received responses from five of the
peer reviewers.
We reviewed all comments received from the peer reviewers for
substantive issues and new information regarding the listing of
northern Mexican and narrow-headed gartersnakes. All peer reviewers
shared the opinion that a thorough examination of all available
information was conducted in support of listing these gartersnakes.
Peer reviewers also commented that the quality of the information
presented in the proposed rule was very high and the analyses were
thorough. There were concerns expressed regarding whether listing these
gartersnakes as threatened would interfere with ongoing recovery
actions for listed fish species where they co-occur. Another concern
was based on how threats affecting these gartersnakes were prioritized
in their scope and magnitude in the proposed rule. In general, peer
reviewers generally concurred with our methods and conclusions and
provided additional information, clarifications, and suggestions to
improve the final rule. Peer reviewer comments are addressed in the
following summary and incorporated into the final rule as appropriate.
Comment 1: The term ``spiny-rayed fish'' has a very specific
scientific meaning, which is not consistent with its use in the
proposed rule. While this group includes some of the nonnative species
of concern, such as sunfish and bass, it does not include others,
specifically the catfishes. Also, the term spiny-rayed fishes as used
here excludes a suite of nonnative fishes that are problematic for
native fish species and likely for northern Mexican gartersnake and
narrow-headed gartersnake, such as nonnative trouts (especially highly
predaceous brown trout (Salmo trutta), red shiner (Cyprinella
lutrensis), and mosquitofish (Gambusia affinis)). The term ``spiny-
rayed fishes'' should either be eliminated from the document and
replaced with accurate terminology or be defined specifically for its
intended use in the rule. The Service should dispense entirely with use
of ``spiny-rayed fishes'' and use only the term ``nonnative fishes.''
Our Response: In the proposed rule, we intended to identify those
species of nonnative fish that were both considered highly predatory on
gartersnakes and also highly competitive with gartersnakes in terms of
common prey resources. The nonnative fish species we view as most
harmful to gartersnake populations include bass (Micropterus sp.),
flathead catfish (Pylodictis sp.), channel catfish (Ictalurus sp.),
sunfish, bullheads (Ameiurus sp.), bluegill (Lepomis sp.), crappie
(Pomoxis sp.,) and brown trout (Salmo trutta). We agree that all
nonnative fish species pose some level of threat to native aquatic
ecosystems. However, it is important to highlight those nonnative fish
species that pose the greatest threat to assist in prioritizing future
conservation actions that are most beneficial to northern Mexican and
narrow-headed gartersnakes. Therefore, we have specifically defined in
the beginning of this final rule, what nonnative fish species are
considered ``predatory'' and what nonnative species we consider
``harmful.''
Comment 2: It would be helpful to the reader to visualize the
historical and current ranges of the two snakes if range maps were
included.
Our Response: Current distribution maps were provided and are
available in the proposed rule to designate critical habitat for the
northern Mexican and narrow-headed gartersnake, which accompanied the
proposed rule to list the species in the Federal Register (78 FR 41550,
July 10, 2013, p. 41586).
Comment 3: The sentence ``Fleharty (1967, p. 227) reported narrow-
headed gartersnakes eating green sunfish, but green sunfish is not
considered a suitable prey item'' needs clarification. Specifically,
the authors need to provide evidence that green sunfish is not a
suitable prey item. Just because green sunfish has spines in their
medial (caudal excluded) and lateral fins does not mean that it is not
suitable prey.
Our Response: We added further clarification to this text to
support this statement in the final rule under ``Habitat and Natural
History'' for the narrow-headed gartersnake.
Comment 4: Please provide examples of ``barriers to movement'' of
narrow-headed gartersnakes and additional information on the ``salvage
efforts'' in the discussion leading into Table 2.
Our Response: We provided examples and additional information in
the text in the final rule under ``Current Distribution and Population
Status.''
Comment 5: With respect to nonnative fish species in the Gila River
basin, all were either intentionally or accidentally introduced by
humans; there is no evidence that any species gained access to the
basin through natural colonization as inferred in the proposed rule.
Our Response: We agree that no evidence exists to support
unassisted migration of nonnative fish species into the Gila River
basin from outside the basin. However, we acknowledge that harmful
nonnatives, once introduced, are fully capable of naturally dispersing
within the watershed where habitat connectivity permits. This latter
concept was the impetus for the notion of ``natural colonization'',
which is also referred to as dispersal.
Comment 6: The proposed rule mentions only trout of the genus Salmo
as occurring in habitat occupied by either gartersnake. Rainbow trout
(Oncorynchus mykiss) and brook trout (Salvelinus fontinalis) also
occur.
Our Response: This oversight has been corrected in the final rule
in the subsection ``Fish'' within the subheading ``Decline of the
Gartersnake Prey Base.''

[[Page 38724]]

Comment 7: The statements that nonnative fish ``tend to occupy the
middle and upper zones in the water column'' while native fish tend to
occur ``along the bottom'' is not entirely accurate. For example, all
of the catfishes (all of which are nonnative in the Gila River system)
are benthic in habit, and these are among the species considered
harmful to gartersnakes and their prey. Among native fishes in the Gila
River system only loach minnow would be characterized as benthic,
although most native suckers and minnows (chubs largely excluded) do
forage along surfaces, including the bottom. Moreover, large numbers of
native fish, longfin dace (Agosia chrysogaster) in particular, occur in
shallow habitats where differentiating a position in the water column
is problematic.
Our Response: We have amended the discussion in the subsection
``Fish'' within the subheading ``Decline of the Gartersnake Prey Base''
in the final rule to specify which groups of native or nonnative fish
are likely to occur where in the water column.
Comment 8: It seems unlikely that Yaqui catfish were suitable prey
for gartersnakes, given their stiff pectoral and dorsal spines, and
humpback chub likely never co-occurred with either gartersnake.
Woundfin, conversely, has records from the lower Salt River at Tempe
and would have been a listed prey species.
Our Response: We have removed humpback chub and Yaqui catfish, and
added woundfin, as species noted that were possible prey species of
either gartersnake and that are now listed under the Act.
Comment 9: Brown trout are highly predacious and should be
considered as harmful nonnative wildlife by the Service.
Our Response: We have reevaluated potential effects of brown trout
predation on native aquatic vertebrates and concur that brown trout are
highly predatory in all size classes and in a wide range of water
temperatures. Thus, we have identified the brown trout as a
``predatory'' nonnative fish species and discuss its ecological
significance in the final rule in the subsection ``Fish'' within the
subheading ``Decline of the Gartersnake Prey Base.''
Comment 10: In the proposed rule, the Service identified several
streams in Arizona or New Mexico where nonnative fish present
management issues. However, nonnative fish are a concern for management
of native fish throughout Arizona and New Mexico, not only those
streams specifically mentioned. They are an issue where they already
are present and in those habitats where they may invade or be
introduced in the future, which included virtually any watercourse or
body of water throughout the region.
Our Response: We added language to reflect this fact in the
subsection ``Fish'' within the subheading ``Decline of the Gartersnake
Prey Base.''
Comment 11: With respect to potential effects from fisheries
management activities, it would appear that gartersnakes still occur in
many of the streams that have received piscicide treatments. If so, why
are these streams and their renovation history discussed in the
proposed rule because there is no evidence that chemical treatment in
any of these instances eliminated, depleted, or otherwise impacted a
resident gartersnake population. The loss of a major portion, or
entire, prey base of a gartersnake population will result in the loss
of individuals from starvation, which is expected to result in weakened
population viability and, potentially, the loss of that population
depending on the presence of other stressors, the proximity of the
next-closest source population, and the status of the population prior
to treatment.
Our Response: If the intent of a renovation is to remove all fish
from a stream, and the stream is occupied by either gartersnake, which
wholly or partially requires fish in their prey base, the logical
conclusion is that adverse effects to gartersnakes, at least
temporarily, are likely under these circumstances. The presence of
either gartersnake in a treated stream after the treatment is not
evidence that no adverse effects to individuals have occurred.
Comment 12: Traditionally, pre-treatment salvage and post-treatment
restocking favor larger-bodied size classes of native fish, which could
reproduce and provide smaller prey for gartersnakes over a period of
time. Small-bodied species would also be saved for salvage and
restocking, but are more difficult to find. How are the interests of
the gartersnakes rectified in these situations? Alternatively,
gartersnakes themselves could be salvaged and restocked at a later date
after a prey base has been established.
Our Response: We agree that fish salvage operations, prior to
treatment, are likely to favor larger individuals that may exceed the
size classes most preferred by gartersnakes as prey. For this reason,
we intend to explore partnerships and opportunities for raising native
fish of appropriate size classes in hatchery settings for subsequent
release into treated streams, post treatment. Based upon our evaluation
of the literature and cooperative work with gartersnakes, alternative
prey species and appropriate size classes are well-understood. We are
not, however, aware of any studies that focused on how long a
gartersnake could go without food before physiological stress or
starvation. We do know that, compared to snakes within other genera or
families, gartersnakes have a relatively fast metabolism and are active
foragers, implying that physiological stress or starvation may be more
of a concern in the absence of prey.
There are significant challenges with salvaging gartersnakes for
long-term captivity. First, facilities with the space, equipment, and
knowledge to care for larger numbers of gartersnakes for long periods
of time are very few, and currently those that are capable, are nearly
at full capacity because of their involvement with captive breeding
efforts. Second, narrow-headed gartersnakes have proven to be difficult
to maintain in captivity due to their unique physiological and prey
requirements. Lastly, it may prove difficult if not impossible to
salvage gartersnakes from low-density populations within complex
habitat and therefore the risk of their complete extirpation from a
renovation activity is elevated. In the event an isolated population is
extirpated, the risk of forever losing their unique genetic lineage is
also elevated and unacceptable.
Comment 13: The discussion about electrofishing impacts to
gartersnakes is misleading and misinformed. The statement that
``gartersnakes present within the water are often temporarily paralyzed
from electrical impulses intended for fish'' is true only to the extent
that the gartersnake actually is present and available to intercept the
electrical current. Personal experience and interviews with colleagues
suggest that encounters of electroshockers and gartersnakes are
exceptionally rare, not ``often'' as suggested by the Service. Next,
use of the term ``electrocution'' is inappropriate as it by definition
means killing, which is not only rare for electroshocked fishes, but
unknown for gartersnakes.
Our Response: The statement in the proposed rule, ``gartersnakes
present within the water are often temporarily paralyzed from
electrical impulses intended for fish'' was intended to mean that
gartersnakes had to be present in the water and within the affected
radius of the electroshocker, otherwise the assumption is they would
not be affected and thus, not detected. By use of the term
``electrocuted,'' it was not

[[Page 38725]]

our intention to imply that gartersnakes which received an electrical
charge were mortally wounded. We have removed the use of this term from
the final rule. ``Detections'' as cited in the document are not
``electrocutions.'' Reports of gartersnakes detected during
electrofishing may be misleading because it is unclear if those
attributed to Hellekson (2012, pers. comm.) were during surveys for
fishes or for reptiles and amphibians, while detections reported by
Pettinger and Yori (2011) apparently were during surveys for Chiricahua
leopard frog and not for fishes. Lastly, the references cited where
gartersnakes were detected via electroshocking referred to fisheries
surveys; electroshocking is not a recognized method for aquatic
herpetofauna surveys. We amended the text in this final rule under the
heading ``Risks to Gartersnakes from Fisheries Management Activities,''
subheading ``Mechanical Methods'' to better communicate our assessment
of the potential effect of electrofishing surveys on gartersnakes.
Comment 14: The term ``self-baiting'' is rarely if ever used by
fisheries professionals in reference to wire minnow traps.
Our Response: We used the term ``self-baiting'' with respect to how
these types of mechanical traps work for gartersnake surveys, which is
indeed through the function of self-baiting with minnows, amphibian
larvae, etc. However, the term's use in discussing the use of these
traps for fisheries surveys was inaccurate, and the term has been
removed from the sentence where it was used in the proposed rule.
Comment 15: The proposed rule provides two references documenting
examples of gartersnakes that drowned in wire minnow traps. One
reported from Holycross et al. (2006) and the other from Boyarski
(2011). Holycross et al. (2006) never mentions the word ``drown'' in
their report. It is also noted that these few minnow-trap related
fatalities occurred during surveys specifically to capture
gartersnakes, that is, the investigators were targeting gartersnakes
with this effort. The inadvertent capture of a gartersnake is an
exceptionally rare occurrence and has not been reported from fisheries
survey activities.
Our Response: The reference of Holycross et al. (2006) describes
the flooding event, but not the death of an individual gartersnake,
which was incidentally killed in a trap when flooding occurred
(observed by Service biologists). We discuss the potential threat of
gartersnake fatality from minnow traps used in fishery surveys because
the threat is real. Gartersnakes will forage at any position within the
water column; northern Mexican gartersnakes often forage at the water
surface and in intermediate depths, while the narrow-headed gartersnake
forages most frequently along the bottom. The fact that minnow traps
for fishery surveys are generally set overnight and checked at least
twice daily, and always during morning does not alleviate this threat.
The reason that minnow traps used for gartersnake surveys are set at
the surface with half of the trap above the water line is to prevent
drowning of captured gartersnakes. When used for fisheries purposes,
these traps incidentally self-bait with gartersnake prey species (the
intended purpose is to capture fish) and are set below the water line.
Checking the traps a few times daily will not prevent air-breathing,
nontarget organisms from drowning if captured. We also note that both
gartersnake species can be active at night, but are not certain their
activity includes foraging. We did not intend to portray that the
incidental capture of gartersnakes by minnow-trapping for fishery
surveys happens frequently, but where it could incidentally result in
the loss of one or more reproductive females in low population
densities, a population-level effect could result. Lastly, we clarified
in the final rule that funnel traps are not used in fishery surveys.
Comment 16: Relative to fisheries management activities, it cannot
be stressed enough that there currently is no effective strategy to
eliminate harmful nonnative fishes other than use of piscicides and
their use is critical for native fish recovery. It should also be noted
that fisheries activities effects are trivial compared to those
attributed to herpetological activities and other human factors.
Our Response: We concur that chemical renovations are vital to
native fish recovery. To further clarify the vital importance of
piscicide use in the recovery of the gartersnakes' native prey base and
the gartersnakes themselves, we amended the passage in the final rule
under the heading ``Risks to Gartersnakes from Fisheries Management
Activities,'' subheading ``Piscicides.''
We are confident that the discussion in the proposed and final
rules attributed to the potential threats to these gartersnakes from
the implementation of fishery management activities is objective,
thoroughly referenced, and balanced. We agree that other human-caused
threats can pose comparably greater risks to gartersnakes. But, we
disagree with the notion that incidental fatality from herpetological
surveys are potentially more significant than activities that eliminate
an entire suite of prey species from habitat occupied by gartersnakes.
We also stress that listing these two gartersnakes should not be
construed as an obstacle to native fish recovery under any
circumstances. Rather, the recovery of these gartersnakes is
inextricably and ecologically linked to native fish recovery.
Comment 17: How many stock tanks are known within the range of
northern Mexican gartersnake and what proportion of these meet criteria
for being ``well-managed?'' Few stock tanks are well-managed, and most
lack peripheral vegetation that would function as suitable habitat for
gartersnakes. The Service provides no information to address these
questions, which is necessary to evaluate the actual or potential
contribution of stock tanks to gartersnake conservation.
Our Response: The actual number of stock tanks that occur within
the distribution of the northern Mexican gartersnake is not currently
known because not all tanks are georeferenced in GIS databases.
However, based upon their common occurrence on the landscape, we
conclude that the number is very large, possibly in the 100's. We also
have no quantitative data on the number of tanks that are ``well-
managed.'' Regardless, based upon our collective knowledge of how these
habitats are used by northern Mexican gartersnakes and primary prey
species, particularly in southern Arizona, we consider their existence
as a vital contribution to conservation of the northern Mexican
gartersnake. Based on our knowledge of habitat variables that best
predict whether a gartersnake population could be sustained, the
presence of a native prey community and the absence of harmful
nonnative species appear to be the most predictive factors. Peripheral
vegetation may provide cover for gartersnakes in stock tanks where
harmful nonnatives occur, but it is not necessary for gartersnake
populations in all circumstances. It may be possible that stock tanks
have replaced, in part, the role of natural cienegas as important
gartersnake habitat, although no direct study has been attributed to
this hypothesis. While stock tanks in different drainages can be
invaded by bullfrogs or crayfish by means of natural dispersal, they
can also represent easily managed habitat to protect against (or
rectify) invasion of harmful nonnative species. For these reasons, we
currently value the

[[Page 38726]]

existence of stock tanks for northern Mexican gartersnake conservation.
Comment 18: Mine spills are a threat to gartersnakes and to their
fish prey. For example, mine spills made the San Pedro River toxic for
a time, and a naturally occurring population of endangered Gila
topminnow in Cocio Wash, Arizona, was exterminated by a mine spill.
Numerous other examples of this threat are available and should be
included.
Our Response: We expanded our discussion of the threat of mining
pollution under the heading ``Environmental Contaminants,'' to include
the example from the San Pedro River.
Comment 19: Regarding the discussion about management emphasis
relative to native and nonnative fishes, it should be acknowledged
that, at least in Arizona, the management priority is recreational
fisheries, and the operative AGFD's policy is ``no net loss'' of sport
fishing opportunities when attempting to balance sport fish and native
fish management. It is well documented by literature cited in the
proposed rule that native fishes and nonnative fishes cannot coexist in
the long term other than under exceptional circumstances.
Our Response: We understand the concern for the future of native
fish and by extension, northern Mexican and narrow-headed gartersnakes.
We included discussion of the ``no net loss'' policy in the final rule
under the heading ``Current Conservation of Northern Mexican and
Narrow-headed Gartersnakes.''
Comment 20: The Service used the presence of a native prey species
as evidence that a given area or stream may be occupied by northern
Mexican gartersnakes. This approach seems optimistic at best, and
perhaps, when the importance of habitat is also considered, not
scientifically justified. If native prey species are present, but the
habitat extent is too small, it is possible that northern Mexican
gartersnakes did not occur or will not persist.
Our Response: In determining whether historically occupied habitat
remains occupied, we considered habitat surrogates in the determination
where gartersnake survey data was limited. Native prey species remain
an important attribute for northern Mexican gartersnake habitat and
their presence in an area is evidence that the resident, native biotic
community may still offer native prey. It is also reasonable to assume
that not every site along a stream course is suitable habitat for
northern Mexican gartersnakes; these sites may be occupied by
dispersing individuals, however. We think that using these habitat
parameters as surrogates for occupied areas by the northern Mexican
gartersnake is an appropriate use of the best available information, in
the absence of more detailed information.
Comment 21: We have recently surveyed and trapped Little Ash Creek
(August 2013); it has abundant nonnative fish species and crayfish,
scarce native dace populations, and very few (n = 1 captured)
bullfrogs. The habitat extent (creek size) is small and we suspect it
no longer supports northern Mexican gartersnakes so the population is
likely extirpated.
Our Response: We appreciate the updated information. However, the
continued presence of some native fish and limited bullfrog detections
are signs that northern Mexican gartersnakes could still exist, albeit
at low or very low abundance, in Little Ash Creek. Moreover, individual
gartersnakes could disperse from the Agua Fria River, to which Little
Ash Creek is a tributary. We have not yet officially adopted a protocol
to establish population extirpation, but at a minimum, we expect such a
protocol should include robust survey data from multiple consecutive
years to account for detectability constraints in low-density
populations. Until such a protocol is adopted, we hesitate to conclude
that gartersnakes are extirpated from a given area, such as Little Ash
Creek.
Comment 22: Additional sites not encompassed by Table 1 include:
Tavasci Marsh (Nowak et al. 2011; population possibly not viable but
likely supported by recruitment from the Verde River); Peck's Lake
(Schmidt et al. 2005; population possibly not viable but likely
supported by recruitment from the Verde River), and Dead Horse Ranch
State Park (Emmons and Nowak 2013; population likely viable).
Our Response: We are aware of these populations and included them
with the Verde River mainstem due to their close proximity.
Comment 23: The proposed rule cites Rosen and Schwalbe (1988, pp.
34-35) for a list of plant species associations for narrow-headed
gartersnake habitat. Reliance on a single citation (whose results were
based on visual encounter surveys) to infer distribution-wide habitat
use is inappropriate. Please include intensive study data from Nowak
and Santana-Bendix (2002) and Nowak (2006) for a more complete look at
narrow-headed gartersnake-plant associations.
Our Response: Rosen and Schwalbe (1988, entire) sampled narrow-
headed gartersnake populations in a multitude of streams across their
range in Arizona and, therefore, represent a more comprehensive list of
plant species associations in a rangewide context. Nowak and Santana-
Bendix (2002) and Nowak (2006) focus solely on one population at Oak
Creek and, therefore, do not account for variability of preferred
habitat across the species' range.
Comment 24: The Service stated that sexual maturity in narrow-
headed gartersnakes occurs at 2.5 years of age in males and at 2 years
of age in females (Deganhardt et al. 1996, p. 328). I suspect this
assertion is overstated and scientifically inaccurate, based on field
studies and on animals currently maintained in captivity. Captive-born
female narrow-headed gartersnakes from the Black River (Arizona)
maintained in captivity did not lay eggs until their third summer, even
though they reached adult size within their second year (Nowak,
unpublished data, 2012).
Our Response: In the absence of other published data, we will
continue to rely on published information regarding the sexual maturity
data presented and referenced. In addition, observations made in
captive situations may be misleading because they may not reflect
factors affecting wild populations.
Comment 25: The proposed rule provided a list of areas where
narrow-headed gartersnakes could be reliably found. The Upper Verde
River, Tonto Creek, and the Blue River should also be included in this
list. While occurring in low densities, individuals in these
populations can still be reliably found with minimal to moderate effort
(e.g., Upper Verde River: Emmons and Nowak 2012a, Emmons and Nowak
2013; Tonto Creek: Madara-Yagla 2010, 2011; and Blue River: Rosen and
Nowak unpubl. data, 2012).
Our Response: The population and survey data reported in Appendix A
provide the basis for where narrow-headed gartersnakes are reliably
found. Populations considered likely viable have received significantly
more field study in most cases and, where they haven't, recent survey
data show robust population densities with minimal survey effort. We
understand the inherent challenges with defining a population's status
with a single phrase or term, but the data do not currently show that
narrow-headed gartersnake populations in the Upper Verde, Tonto Creek,
or the Blue River are near as robust as those identified as likely
viable in Table 2. In the case of Tonto Creek, narrow-headed
gartersnake records are comparably few, and Madara-Yagla (2010, 2011)
address only northern Mexican gartersnakes. Unpublished data from the
Blue River

[[Page 38727]]

were not provided to us, and until those data are provided and
reviewed, we are unable to update the status of that population, if
warranted.
Comment 26: If only 8 to 10 percent of historic populations are
viable, with significant post-fire concerns for populations from
Whitewater Creek and the Black River, should this species be proposed
for listing as ``Endangered?''
Our Response: The current status of the northern Mexican and
narrow-headed gartersnakes meets the definition of threatened, not
endangered. We found that both gartersnakes are not currently in danger
of extinction because they remain extant in most of the subbasins where
they historically occurred, and known threats have not yet resulted in
substantial range reduction or substantial number of population
extirpations to put either species on the brink of extinction. However,
we do find that the ongoing effects of the threats make both species
likely to become endangered in the foreseeable future. Please see the
sections entitled ``Determination for Northern Mexican Gartersnakes''
and ``Determination for Narrow-headed Gartersnakes'' for further
discussion of our determinations.
Comment 27: Regarding Table 2, state that the population at Saliz
Creek, New Mexico is introduced; three recaptured individuals were
found there in 2013; however, the population is likely not viable. In
addition, I do not know of any post 1990's records from the San
Francisco River in New Mexico; this population is ``likely extirpated''
(Hibbitts et al. 2009).
Our Response: Saliz Creek is a tributary to the San Francisco
River. The San Francisco River formerly had a robust population of
narrow-headed gartersnakes. Saliz Creek lies between two additional
tributaries to the San Francisco River, Whitewater Creek and the
Tularosa River, which historically and currently (respectively) also
had robust populations. Saliz Creek also boasts a largely native fish
community, with the exception of its lower-most reach. Furthermore,
prior to 2012, a total of 10 person-search hours were spent surveying
for narrow-headed gartersnakes attributed to Saliz Creek, which does
not constitute adequate survey effort to determine presence or absence.
No compelling data suggest that narrow-headed gartersnakes never
historically occurred in Saliz Creek prior to their release in 2012.
Regarding population status in the San Francisco River, more recent
survey efforts from 2009-2011, consisting of approximately 100 person-
search hours, reconfirmed the narrow-headed gartersnake as extant in
the San Francisco River in New Mexico with documentation of three
narrow-headed gartersnakes (Hellekson 2012a, pers. comm.). Therefore,
we treat this population as likely not viable rather than likely
extirpated.
Comment 28: The statement attributed to Rosen et al. (2001, p. 22)
that the presence and expansion of nonnative predators is the primary
cause of decline in northern Mexican gartersnakes and their prey in
southeastern Arizona may not have been properly characterized. This
paper does not state that nonnative predators are the only factor, but
instead it explicitly states the importance of other factors such as
climate and interspecific competition. Also, the paper's conclusions
are subjective and are generally presented as testable hypotheses, and
should be cited with caution rather than presented as scientifically
tested facts.
Our Response: We agree that Rosen (2001) did not state that
nonnative species are the only reason for northern Mexican gartersnake
declines in southern Arizona, rather harmful nonnatives were considered
as the primary cause at most sites surveyed, as described in the
proposed rule. Rosen (2001, p. 21) postulated that ``natural climatic
fluctuation'' may be responsible for a northern Mexican population
decline at one site in southern Arizona, which is not to say that it
was regarded in equal value as harmful nonnative species in affecting
northern Mexican gartersnakes in southern Arizona. Interspecific
competition was also discussed in Rosen (2001) as a cause for concern
at some sites. We evaluated the role of climate change and
interspecific competition in other sections of the proposed and final
rules as their discussion is not appropriately placed in the section
referred to here. However, we changed the word ``concluded'' in this
sentence to ``hypothesized.''
Comment 29: The proposed rule discusses the importance of a varied
prey base and cites a study that experimented with food deprivation on
the common gartersnake (T. sirtalis). There is no scientifically valid
reason to conclude that a varied diet could not include bullfrogs as a
replacement for native leopard frogs, especially where bullfrogs are
currently abundant. It may not be scientifically valid to infer that
foraging, physiological, and behavioral data collected from the common
gartersnakes will be representative of the populations of southwestern
gartersnakes. As such, I disagree that the common gartersnake is an
``ecologically similar species'' to northern Mexican gartersnake.
Our Response: We state on several occasions in the proposed rule
that larval and sub-adult bullfrogs are eaten by northern Mexican
gartersnakes in the mid- to larger-size classes. However, bullfrogs are
not always available for gartersnake populations that exist where
native ranid frogs have disappeared, and bullfrogs pose a significant
threat to population recruitment of northern Mexican gartersnakes in
many areas. This impact outweighs any benefit of their existence as a
source of prey. We consider relevant data from the common gartersnake
as valid for a general biology discussion as both species have a varied
prey base and both species occupy varied habitats, albeit the northern
Mexican gartersnake may be more aquatic.
Comment 30: In the discussion of the role of harmful nonnative
species relative to other threats implicated in the decline of native
fisheries, the proposed rule stated, ``Aquatic habitat destruction and
modification is often considered a leading cause for the decline in
native fish in the southwestern United States. However, Marsh and Pacey
(2005, p. 60) predict that despite the significant physical alteration
of aquatic habitat in the southwest, native fish species could not only
complete all of their life functions but could flourish in these
altered environments, but for the presence of (harmful) nonnative fish
species, as supported by a `substantial and growing body of evidence
derived from case studies.''
I would like to see a more robust consideration, including
citations beyond March and Pacey (2005), of the importance of the loss
of habitat in native fish declines relative to harmful nonnative
species. It is my understanding that many species of native fish rely
on seasonal flooding to induce spawning.
Our Response: We agree that the role of a natural flood regime is
extremely important to the maintenance of native fish populations as
well as important in (temporarily) depressing resident harmful
nonnative fish populations, and the proposed rule provides a thorough
review of this topic, citing numerous references. Natural flood regimes
have largely disappeared from several large perennial mainstem rivers
and from a small number of streams associated with small reservoirs in
Arizona and New Mexico. However, many native fish are doing markedly
poorly across their ranges where they co-occur with harmful nonnative
fish species, regardless of whether a natural flood

[[Page 38728]]

regime exists or not. No other threat is as geographically ubiquitous
as that from harmful nonnative species, which is clearly reflected, in
robust fashion, within the published literature. The proposed and final
rules review how threats to aquatic habitat that are not directly
associated with nonnative species have also resulted, in part, in the
decline of numerous native fish species in the United States and
Mexico. Based on our consultations with native fish experts in private
and public sectors and the breadth of available literature, the
findings of Marsh and Pacey (2005) are consistent on the scope and
magnitude of the effect of harmful nonnative fish on the decline of
native fish species.
Comment 31: In the discussion of the effects of bullfrogs on
gartersnake populations, the proposed rule states that bullfrogs may
lower recruitment and lead to population declines of northern Mexican
gartersnake populations. This is an over-generalization and is not
supported by scientific data across the range of the species. In
addition, the conclusion that bullfrogs more effectively prey on young
age classes is likely true but has not been substantiated by
experimental studies. This statement does not accurately reflect the
situation in the Verde Valley (AZ), where all age classes of northern
Mexican gartersnakes are well-documented to co-occur with bullfrogs.
Low recruitment could be due to a number of factors other than
nonnative species predation.
Our Response: The scientific community is in consensus, and we
agree, that bullfrogs negatively affect recruitment of northern Mexican
gartersnakes in areas where gartersnakes occur with bullfrogs in high
densities. The presence of other harmful nonnatives or other possible
threats can confound our understanding of the specific effects of
bullfrogs, and we presented an extensive discussion of this issue
citing numerous scientific references. We believe our treatment of the
ecological effects of bullfrogs on northern Mexican gartersnakes is
well supported by the best available scientific information. It is true
that published examples of this concern come from gartersnake
populations in southern Arizona, and we agree that any gartersnake
population could face a unique array of potential threats that could
also effect successful recruitment across its distribution.
Comment 32: Given that northern Mexican gartersnakes have been
documented to prey on bullfrogs in multiple locations, it is misleading
and scientifically inaccurate to imply that the recovery of northern
Mexican gartersnakes is dependent on recovery of native leopard frogs.
Our Response: We agree that bullfrogs in their larval and subadult
age classes can be prey for northern Mexican gartersnakes and, in some
populations, may be their primary prey items. However, unlike native
leopard frogs, bullfrogs in their adult age class become a significant
threat to resident northern Mexican gartersnake populations and can
depress or eliminate recruitment of young snakes into the reproductive
age classes within a population. Adult bullfrogs can extirpate a
population of northern Mexican gartersnakes by directly preying upon
snakes and out-competing them for available prey. Bullfrogs can also
prevent the recolonization of an area by dispersing gartersnakes via
these same ecological mechanisms. The view that bullfrogs are an
adequate substitute for native leopard frogs in the ecosystems of the
northern Mexican gartersnake is not supported by the best available
scientific information and, therefore, we do not support this
supposition.
Comment 33: Regarding the incidence of tail injuries in gartersnake
populations, observations of this phenomenon in upper Oak Creek,
Arizona, at sites where crayfish and bullfrogs are absent, seem to
point to fish or bird predation attempts, given wide oval injury marks
with pointed ends.
Our Response: We noted in the final rule under the heading ``The
Effects of Predation-Related Injuries to Gartersnakes'' that tail
injuries could be caused by other predators other than strictly
bullfrogs or crayfish.
Comment 34: A more quantitative evaluation on habitat loss to
dewatering would be worth sharing, assuming any is available. Extensive
dry reaches in the San Francisco River now exist, including locations
that have historic records for the narrow-headed gartersnake.
Our Response: We agree that a quantitative evaluation of dewatered
stream habitat would be important to fully characterize this threat.
However, we were unable to locate georeferenced data to assist in this
effort and had to rely on existing literature to describe this threat.
Comment 35: The adverse effects of crayfish on narrow-headed
gartersnakes may be overstated, at least with respect to New Mexico. A
clear connection between crayfish presence and declining narrow-headed
gartersnake populations has yet to be definitely made in field study.
The two sites with the highest apparent densities of narrow-headed
gartersnakes in New Mexico also have fairly abundant crayfish and
bullfrogs. When small- to medium-sized native fish are abundant,
crayfish seem to be tolerated by the gartersnakes. In New Mexico very
few sites have crayfish that can reach sizes where they would be a
potential predator on narrow-headed gartersnakes; in virtually all
other sites, the crayfish are uniformly small in size due to periodic
years with flooding that extirpates them or drastically lowers their
numbers.
Our Response: We added discussion under ``Effects of Crayfish on
Native Aquatic Communities'' to reflect extraneous influences on the
threat of crayfish to gartersnake populations while noting that the
available literature strongly suggests that crayfish in larger size
classes or in high densities are cause for significant concern for
gartersnakes and their prey species, especially with other threats
simultaneously affecting gartersnake populations.
Comment 36: The Middle Fork Gila River, Little Creek, and South
Fork Negrito Creek populations of narrow-headed gartersnakes were
identified as likely having been impacted by the 2012 Whitewater-Baldy
Complex fire and considered as not likely viable. Post-fire condition
data were largely not available in 2012, but information from 2013
indicated that fish populations were showing signs of recovery.
Our Response: Based on the potentially significant effects of
wildfire on fish populations and, therefore, on the narrow-headed
gartersnake (detailed in the proposed and final rules), we
conservatively assessed these narrow-headed gartersnake populations as
likely not viable, given the size and scope of the Whitewater-Baldy
Complex Fire. We were also involved with narrow-headed gartersnake
salvage operations from the Middle Fork Gila River, strictly because it
was assessed to have been heavily impacted by wildfire. We treat
Appendix A as a ``living'' document and can update the status of
gartersnake populations as necessary and as population data become
available, for sharing and conservation and recovery planning purposes.
Comment 37: Narrow-headed gartersnakes in the mainstem San
Francisco River are reliably detected, and the population should be
considered as likely viable.
Our Response: Gartersnake captures per unit effort have
significantly declined in the San Francisco River since they first
became regularly monitored in the 1980's. While individuals are still
detected,

[[Page 38729]]

population data we present in Appendix A clearly describe the narrow-
headed gartersnake population in the San Francisco River as one in
significant decline.

Federal Agency Comments

Comment 38: The proposed rule references the Management Indicator
Species, Regional Foresters' Sensitive Species List, and land
management decisions, but states that there are no specific protective
measures conveyed to these species. However, the northern Mexican and
the narrow-headed gartersnakes have been considered sensitive species
on the Regional Forester's sensitive species list for a long time. An
impact to these species is, therefore, considered as part of the
environmental analysis for every forest management action. The USFS
Sensitive Species Policy is to manage for viable populations of these
species. Further, the USFS policy for sensitive species provides
protective measures such as direction to ``Avoid or minimize impacts to
species whose viability has been identified as a concern'' (Forest
Service Manual (FSM) 2670.32 3). A decision that would impact
sensitive species ``. . . must not result in loss of species viability
or create significant trends toward Federal listing'' (FSM 2670.32
4).
Our Response: We more accurately summarized what protections are
afforded to ``sensitive species'' in the final rule. We found no
examples (although we did not have the opportunity to review all
previous planning documents the USFS has developed in the past), and we
were not provided any examples of measures that have been implemented
by the USFS to ``avoid or minimize impacts'' to either the northern
Mexican or narrow-headed gartersnake. We look forward to working with
the USFS in developing such measures.
Comment 39: What is the basis for assuming there is ``continued
anxiety'' from the public regarding rotenone use?
Our Response: We have been an active participant in the public
debate over potential threats to human health from rotenone use. The
new and very process-rich procedures now in place for planning and
implementing rotenone use in Arizona are testament that piscicide use
in the recovery of rare and listed fish is still considered
controversial; although it is scientifically well-supported that there
is no public harm from its use.
Comment 40: We disagree that, on the Gila National Forest, heavy
recreation use within occupied narrow-headed gartersnake habitat is
thought to impact populations along the Middle Fork Gila River,
mainstem Gila River between Cliff Dwellings and Little Creek, and
Whitewater Creek from Catwalk to Glenwood. Recreation use along the
Middle Fork Gila River is certainly not heavy; most use is by hikers
and backpackers utilizing the existing trail to access the Gila
Wilderness. The stream between the Cliff Dwellings and Little Creek is
the West Fork Gila River not the mainstem. This reach of stream is
located on National Park Service, NMDGF, and USFS lands. The majority
of this reach is on the NMDGF's Heart Bar Wildlife Area. Whitewater
Creek from the Catwalk to Glenwood is predominately private property.
Approximately 0.25 mile of stream, downstream of the Catwalk, is USFS
lands and the remainder of this reach is private property.
Our Response: We amended this discussion in the final rule to state
that much of the recreation use in these areas is related to hiking and
backpacking, which are generally not considered a threat to
gartersnakes outside of the fact that increased human visitation leads
to more gartersnake encounters and potentially more killing of
gartersnakes where the foot trail is near the canyon bottom.
Comment 41: Throughout the proposed rule and during personal
communications with the Service, livestock grazing has not been
identified as a significant threat to these species. However, the
Service appears to be saying that, unless livestock are excluded by
fencing, adverse effects may occur. The Service goes further by stating
that the adverse effects of livestock are somehow most likely to occur
when nonnative species are present but that the species are resilient
to these disturbances if nonnatives are absent. So, grazing along a
stream adversely affects the species if nonnatives are present but does
not have these same impacts if nonnatives are absent?
Our Response: We continue to believe that livestock grazing is
largely compatible with northern Mexican and narrow-headed gartersnakes
based on the species' apparent resiliency to perturbations to their
physical habitat, depending on the resident aquatic community. In our
literature review and field experience, we found populations of these
gartersnakes to be resilient to activities that affect their physical
habitat (vegetation abundance, structure, composition) when harmful
nonnative species are absent or at low levels that allow for effective
recruitment of snakes in the population. When recruitment of
gartersnakes within a population is hampered by harmful nonnatives,
this resiliency is diminished and the presence of adequate vegetation
cover for protection against these nonnatives becomes more important.
When Federal actions are planned, all aspects of project evaluations
should consider potential effects to whatever prey base the gartersnake
population is using in a given area. This idea should be the logical
``framework'' used in developing projects in gartersnake habitat to
manage aggressively against harmful nonnatives to improve population
resiliency and recruitment of gartersnakes. We also note that ``adverse
effects'' can have varying degrees of magnitude and scope and that,
through section 7 of the Act, most activities that could adversely
affect species include measures to reduce effects and potential for
take though the issuance of an incidental take permit.
Comment 42: While nonnative, spiny-rayed fish such as green sunfish
and smallmouth bass were common in the lower reach of Turkey Creek near
its confluence with the mainstem Gila River prior to the Dry Lakes
Fire, they did not make up the majority of the fish community. More
upstream reaches were occupied by native fishes including Gila chub,
speckled dace, Sonora and desert suckers, and longfin dace along with
Gila X Rainbow trout hybrids. All of the native species survived the
fire runoff events, and, although populations were depressed for some
time, they had recovered well until recent fires.
Our Response: We amended this discussion in the final rule to more
accurately describe the fish community and effects of wildfire on
Turkey Creek.
Comment 43: We disagree that significant threats to these
gartersnakes, such as those related to nonnative species, are not
addressed on USFS lands. The role of the USFS is to manage land,
addressing the needs of species' habitat. Management actions related to
nonnative fish and aquatic species stocking, control, or eradication is
under direction of the State. Collaborative efforts are occurring on
USFS lands to improve species' habitat through construction of fish
barriers and stream chemical renovations.
Our Response: We acknowledge the proactive measures taken by the
USFS to assist in restoring fish communities to wholly native
assemblages.
Comment 44: The proposed rule states that USFS management policies
of the past favored fire suppression. However, new policies have
allowed for managing wildfires that have a resource benefit, as well as
prescribed fire. The Guidance

[[Page 38730]]

for Implementation of Federal Wildland Fire Management Policy is the
Department of Agriculture's single cohesive Federal fire policy. This
policy contributes to landscape restoration, controls invasive species,
reduces uncharacteristic wildfire across the broader landscape, and
improves the resiliency of these potential natural vegetation types to
adapt to climate change.
Our Response: We have updated this discussion under the heading,
``High-Intensity Wildfires and Sedimentation of Aquatic Habitat'' in
the final rule to include reference to the updated fire policy and what
it hopes to achieve in the mid to long term.
Comment 45: The proposed rule states that the 2011 Wallow Fire
impacted 97 percent of perennial streams in the Black River subbasin
and 70 percent of perennial streams in the Gila River subbasin. We
request the Service clarify how they are defining a subbasin.
Typically, a subbasin is a fourth code Hydrologic Unit. We do not
consider the Wallow Fire to have affected any of the Gila River
subbasins in New Mexico.
Our Response: We use the term subbasin in a general sense as a
stream basin within a larger stream basin. We further defined the area
impacted by the 2011 Wallow Fire as within Apache-Sitgreaves National
Forest, White Mountain Apache Indian Tribe, and San Carlos Apache
Indian Reservation lands in Apache, Navajo, Graham, and Greenlee
counties in Arizona, as well as Catron County, New Mexico. We recommend
the review of InciWeb (2011), Meyer (2011; p. 3, Table 1), and Coleman
(2011, pp. 2-3) for information on the effects of the 2011 Wallow Fire.
Comment 46: On the Apache-Sitgreaves National Forest forested
vegetation types, historic fire-return intervals varied from frequent,
low-intensity surface fires in ponderosa pine types (every 2-17 years),
to mixed-severity fires in wet mixed-conifer forests (every 35-50
years), to high-severity, stand-replacement fires of the spruce-fir
ecosystems (every 150-400 years).
Our Response: We included these fire-return interval data under the
heading, ``High-Intensity Wildfires and Sedimentation of Aquatic
Habitat'' in the final rule.

Comments From States

Comment 47: The AGFD recognizes that both species have declined
considerably throughout their respective ranges in Arizona, and
acknowledge that listing under the Act is warranted. We also applaud
the Service's decision to propose a 4(d) rule that would exempt take of
northern Mexican gartersnakes as a result of livestock use at or
maintenance of livestock tanks located on non-federal lands. We also
encourage the Service to continue to work closely with the AGFD to
effect meaningful conservation actions for both species.
Our Response: We agree, and we look forward to continued
coordination with the AGFD in addressing the most serious threats that
affect either species and to exploring opportunities for recovery with
Federal, State, and local partners and stakeholders.
Comment 48: The statement that ``The decline of the northern
Mexican gartersnake is primarily the result of predation by and
competition with harmful nonnative species . . .'' should be modified
to reflect that this is a leading theory, but not necessarily true.
Our Response: We think that harmful nonnative species (bullfrogs,
crayfish, and warm-water, predatory fish) are the primary driving
factors behind the decline of the northern Mexican and narrow-headed
gartersnake. In the proposed and final rules to list these
gartersnakes, we reviewed the best available scientific and commercial
information to reach this conclusion. We do acknowledge that other
threats such as climate change-induced drought, dewatering of habitat,
large-scale wildfires, and others may have also significantly
contributed to the decline of these gartersnakes, often in synergistic
fashion with other threats affecting primary prey species. We also
acknowledge that some populations of northern Mexican gartersnakes in
particular, have persisted in the presence of harmful nonnative species
to which further study is under way. However, these ecological
situations are rare within the distribution of these gartersnakes, as
evidenced by widespread population declines, and they should not be
construed as evidence that either gartersnake is ecologically
compatible with harmful nonnative species in the long term. Rather, the
scientific information is convincing that harmful nonnative species are
largely responsible for the declines in these gartersnakes.
Comment 49: Reducing the status of the species at each historical
locality as either ``likely viable,'' ``likely not viable,'' or
``likely extirpated'' as described in tables 1 and 2 may not accurately
capture the status of gartersnake populations. Perhaps an ``Unknown''
category would have been useful. Also, a low-density population does
not always indicate that the population is not viable.
Our Response: We agree that adequately describing the status of
each population at each historic locality as falling into one of three
categories is challenging. However, the general lack of data on many
populations does not allow us to refine these categories further. In
most cases, we have more information on the presence of threats at each
locality than good information on the resident gartersnake population.
It was our interpretation that, in the presence of known, and in some
cases severe, threats that a low-density population is, at a minimum,
at risk of losing viability, most notably from effects to reproduction
and recruitment such as in the presence of harmful nonnative species.
Additionally, the process of designating critical habitat requires
us to create a rule set for determining whether the species is present
or not in each historic locality, therefore, a category called
``Unknown'' is not appropriate. Appendix A provides background
information that contributed to our site-by-site determinations of
population status.
Comment 50: We caution against using percentages to express
possible population extirpations or shifts to low densities because
unrealistic expectations of recovery can be established.
Our Response: We use percentages in this listing rule and others to
capture the rangewide context of the status of a given species'
populations to allow the public a coarse, quantitative assessment of
the perceived status of a species, given the best available scientific
and commercial data.
Comment 51: We suggest removing the word ``harmful'' when referring
to the suite of nonnative species that have been identified as the most
incompatible with the gartersnakes. While they may be incompatible,
they are not harmful in a general context.
Our Response: We use the adjective ``harmful'' to distinguish those
nonnative species that pose unique ecological risks to sustaining wild
populations of northern Mexican and narrow-headed gartersnakes and
their prey species. We consider bullfrogs, crayfish, and warm-water,
predatory sport fish as ``harmful nonnative species.'' This distinction
is based on the predatory, or otherwise, notably adverse interactions
these species have with the gartersnakes and their prey. This
distinction is important because not all nonnative species are
completely incompatible with gartersnakes, and some are used as prey
for wild gartersnake populations; nonnative trout are an example.

[[Page 38731]]

Comment 52: There are no direct data to prove that declines in
native leopard frogs have contributed to declines in northern Mexican
gartersnake populations. The Service should caveat the statement with a
degree of uncertainty.
Our Response: We specifically used the word ``contributed'' to
acknowledge that leopard frog declines are a contributing factor to
northern Mexican gartersnake declines, not the sole factor. As noted by
the AGFD, leopard frogs are an extremely important component to the
northern Mexican gartersnake's prey base--a fact also accepted within
the scientific community and demonstrated in field study.
Comment 53: Potential risks to gartersnake populations from
fisheries management activities were mischaracterized in the proposed
rule. Potential effects to gartersnakes are evaluated by the AGFD
though an Environmental Assessment Checklist process.
Our Response: In our evaluation of how fisheries management
activities could adversely affect gartersnake populations, we reviewed
procedures specific to fisheries management as provided in adopted
protocols. The Environmental Assessment Checklist process is a
parallel, internal process implemented by the AGFD in planning
exercises that applies to multiple types of management activities
considered by the State. We have added discussion of this process to
the final rule under the heading ``Risks to Gartersnakes from Fisheries
Management Activities'' and appreciate that potential effects to these
gartersnakes (or any nontarget species) are fully evaluated prior to
implementing any activity within occupied or designated critical
habitat for the gartersnakes.
Comment 54: In Arizona, the trapping and subsequent use of baitfish
in angling is generally constrained to areas where sport fish and sport
fishing dominate, and, therefore, there is little chance the activity
would affect gartersnakes. In addition, regulations specify that bait
fish must be used at the point of capture and not transported elsewhere
for use.
Our Response: We agree that, where angling activities are
concentrated, it is likely due to the presence of sport fish and in the
case where warm-water, predatory fish species are present, it is less
likely that northern Mexican or narrow-headed gartersnakes are
immediately present. However, there are a few areas where angling is
concentrated in habitat that could be occupied by either or both
gartersnake species such as Oak Creek, the Verde River, Tonto Creek, or
Parker Canyon Lake in Arizona where it is possible that effects to
resident gartersnakes could occur. Regardless, we included a statement
in this final listing rule that notes that AGFD requires that baitfish
must be used where they are captured and appreciate being notified of
the regulation and its benefits for gartersnake conservation.
Comment 55: Please elaborate on what is meant by the statement in
reference to the rate of Lake Roosevelt water level fluctuation as a
benefit to harmful nonnative fish species. Reservoir levels there
fluctuate substantially.
Our Response: We agree that water levels in Lake Roosevelt do
fluctuate and further qualified the statement on this issue in the
final rule. We intended to frame this discussion for comparative
purposes. That is to say, that compared to Horseshoe Reservoir, which
is managed to minimize reproduction of harmful nonnative species in
most years, Lake Roosevelt has several times the capacity of Horseshoe
Reservoir and fluctuation in water levels occur at a slower rate. The
rate at which water levels decline in these reservoir systems affects
the reproduction and recruitment of harmful nonnative fish species; the
faster the decline, the more negative the effect.
Comment 56: It is not clear how ``build-out'' (in reference to
human population growth and urban development) will affect Redrock
Canyon (in the vicinity of Patagonia, Arizona).
Our Response: The discussion in the proposed and final rules where
the issue of build-out is addressed refers to the long-term development
plan along the major transportation corridors of I-19, I-10, and I-17
in Arizona. We identified extant gartersnake populations that were
geographically proximal to these proposed corridors which could
experience indirect effects of development and growth in the human
population (which is expected to double by 2030). Redrock Canyon is
near the Town of Patagonia, which is near Nogales and the I-19
corridor. If predictions for development and human population growth in
Arizona are accurate, we expect increased development in the Patagonia
area, higher levels of human recreation on public lands, and possible
effects to water availability as a result of increased regional
groundwater pumping or additional diversions. We acknowledge in the
final rule that, of the areas identified where there could be effects
to gartersnake populations, Redrock Canyon is buffered geographically
more so than other areas identified.
Comment 57: The section of the proposed rule that discusses the
Arizona Department of Water Resources Active Management Areas (AMAs)
overstates the significance of the AMA designation for both gartersnake
species. For example, the Phoenix AMA includes no modern records of
either species and will not affect long-term recovery. In another
example, the Pima AMA includes only short stretches of the Gila River;
the rest of the AMA is outside the range of either gartersnake's
distribution.
Our Response: In our evaluation of the effect of groundwater
pumping on gartersnake habitat, we found several references that
discuss the known hydrological connection between groundwater and
surface flow in southwestern streams. This is an established concept in
the scientific community and the basis for widespread public concern in
several areas of Arizona with respect to surface flows including the
Verde and San Pedro Rivers. We explained how overdrafts in groundwater
use exceed aquifer recharge (conditions that result in an AMA
designation) and result in a cone of depression that can reduce or
eliminate surface flows in affected streams. We listed the AMAs that
both overlap with the historical range of either gartersnake and
provide context for the discussion of effects of increasing human
population growth on gartersnake populations through indirect effects
of groundwater demands. In doing so, we accurately captured the links
in this cause and effect relationship. With respect to the Phoenix AMA,
we acknowledge that effects on gartersnake populations are no longer
occurring. However, it was our intent to discuss the causes of
historical population extirpations, which were a precursor to rangewide
declines observed today. Effects of the development of the greater
Phoenix metropolitan area include effects from increasing regional
demands on groundwater. Aquifer overdrafts were likely contributing
factors in the extirpation of northern Mexican gartersnake populations
in the lower Salt, lower Gila, and lower Agua Fria River systems.
Comment 58: No scientific evidence has been produced that confirms
a relationship between livestock grazing in occupied gartersnake
habitat in the presence of harmful nonnative species and that without
their presence.
Our Response: We concur that no specific scientific study has been
afforded to this specific issue with

[[Page 38732]]

respect to either the northern Mexican gartersnake or the narrow-headed
gartersnake. However, we have documented observations made of
gartersnake populations in Mexico in the presence of harmful nonnative
species, as well as in their absence, in habitat heavily affected by
other land uses such as unmanaged livestock grazing. As discussed at
length in the subsection below entitled ``The Relationship between
Harmful Nonnative Species and Adverse Effects to Physical Habitat,'' we
found a unique opportunity in Mexico to observe populations in habitat
significantly compromised by land use activities such as unmanaged
livestock grazing where the aquatic community was considered wholly
native. Opportunities to observe this scenario in the United States
generally do not occur due to applied grazing management prescriptions
that largely prohibit extreme effects to riparian habitat, and the fact
that harmful nonnative species are largely ubiquitous in habitat
occupied by these gartersnakes in the United States. Species experts
involved in the Mexico survey effort were in consensus that the most
significant predictor of gartersnake occupancy in these affected
habitats was the presence or absence of harmful nonnative species. The
fact that gartersnakes will use vegetative cover to hide from harmful
nonnative species, and the fact that, in the United States, gartersnake
populations that currently persist at seemingly adequate densities in
the presence of harmful nonnatives also occur in habitat with adequate
vegetative cover, provides further support of this relationship. The
best available scientific and commercial data, coupled with the opinion
of species experts, suggests this relationship is most likely real, and
we fully endorse further scientific study of this issue, if that
opportunity exists.
Comment 59: In Mexico, the Mexican gartersnake is listed as
threatened throughout its range in that country and at the species
level of its taxonomy. The discussion of the threatened status of
northern Mexican gartersnake, as it applies to this rulemaking, is,
therefore, misleading given that there are currently 10 subspecies, and
the northern Mexican gartersnake in Mexico occurs in some of the least
accessible and least likely disturbed aquatic habitats in the country.
Our Response: In Mexico, the clear majority of the distribution of
the Mexican gartersnake (T. eques) is composed of the northern Mexican
gartersnake (T. e. megalops). The Mexican gartersnake (T. e. eques)
comprises the second highest percentage of the species' distribution
along the southwestern quadrant of the species' distribution in Mexico
(Rossman et al. 1996, p. 173). The remaining eight subspecies have much
smaller distributions and in some cases are highly endemic; constrained
to perhaps a single lake. In our analysis of the status of northern
Mexican gartersnake in Mexico, we made every attempt to analyze only
those threats that geographically overlap our understanding of the
subspecies' distribution, which supports the position of a weakened
status, commensurate with Mexico's listing. We do not disagree that
there are likely habitats within its distribution in Mexico that remain
largely intact, physically and ecologically. We also note that harmful
nonnative species, once introduced into a system, have an ecological
advantage over native species and will expand their distribution and,
therefore, the scope of their effects on the landscape, much like what
has been observed in Arizona for decades. This fact, and the
preponderance of scientific and commercial data we evaluated that
pertained to threats in Mexico, supports the position taken by the
Mexican Government in listing the Mexican gartersnake (T. eques) as
threatened and is largely applicable to the northern Mexican
gartersnake.
Comment 60: We recommend removing the discussion referring to the
fact that many of the recovery projects for the Chiricahua leopard frog
have not provided direct benefits to the northern Mexican gartersnake.
The Service does not provide citations for their statement that
indirect benefits for both gartersnake species occur through recovery
actions designed for their prey species, and since the Chiricahua
leopard frog was listed under the Act, significant strides have been
made in its recovery and the mitigation of its known threats.
Our Response: In assessing how recovery activities for currently
listed species may benefit either gartersnake, it is important to
discuss both the benefits and limitations of these activities on
conserving or recovering nontarget species such as the northern Mexican
gartersnake. We used reasonable principles in conservation biology in
making the basic assertion that either gartersnake may benefit by
recovery activities implemented for their native prey species, such as
the Chiricahua leopard frog. For example, when harmful nonnative
species removal projects are implemented on regional scales, such as
for bullfrogs, the predation and competition pressure on gartersnake
prey species are reduced, which may lead to significant expansions in
prey species distribution or increases in their biomass or population
densities. This activity benefits the gartersnakes that use these prey
communities. In another example, the construction of a fish barrier to
prevent the upstream migration of harmful nonnative fish into a stream
provides direct benefits to the resident gartersnake population by
reducing predation pressure on the gartersnakes and their prey base. As
for the recovery achievements made for the Chiricahua leopard frog, we
agree that, in some areas, these activities have benefited the
gartersnakes, particularly for the northern Mexican gartersnake where
they have occurred in lentic habitat on landscape scales, and
specifically in southern Arizona. However, many recovery actions
specific to the Chiricahua leopard frog have occurred at specific tanks
higher in the watershed, not within the floodplain of larger perennial
stream systems, where they would yield much more significant benefits
to gartersnake populations.
Comment 61: Maintaining nonnative sport fish populations does not
necessarily ``significantly reduce the potential for the conservation
and recovery on northern Mexican and narrow-headed gartersnakes.'' The
Biological and Conference Opinion issued by the Service that addresses
the AGFD's 10-year sport fish stocking program (``sport fish
consultation'') includes mitigation measures to ``address the effects
of the proposed action and improve the baseline conditions for native
aquatic species.''
Our Response: We agree that maintaining nonnative sport fish
populations in some areas may have little effect or may even benefit
some gartersnake populations. Not all nonnative species have the same
ecological effect on native aquatic communities. For this reason, and
for the purposes of the greater listing analysis afforded to these two
gartersnakes in this rulemaking, we specifically use the phrase
``harmful nonnative species'' when discussing those which significantly
threaten the northern Mexican or narrow-headed gartersnake. As
previously stated, we consider harmful nonnative species to include
bullfrogs, crayfish, and warm-water, predatory fish. The majority of
specific stocking activities that were subject to the sport fish
consultation involved primarily salmonids (i.e., trout), which we do
not consider to be particularly harmful to these gartersnakes or many
of their prey species. For example, in some areas,

[[Page 38733]]

nonnative trout are an important component to the narrow-headed
gartersnake prey base. Stocking activities under the sport fish
consultation that involved harmful nonnative species were few, were
constrained to lentic habitat (lakes, ponds, etc.), and were a
significant factor behind the ``likely to adversely affect''
determination made for these gartersnakes and several of their prey
species.
Comment 62: In the discussion regarding potential ramifications for
gartersnake recovery with respect to watershed-level fisheries
management designations, the conclusions that were drawn seem
premature. Not all nonnative fishes are considered as, or managed as,
sport fish in Arizona, including many of the nonnative fishes that are
problematic for gartersnakes.
Our Response: Our intention was not to predict which watersheds or
particular streams would likely be designated as nonnative sport
fisheries in the future. Rather, we simply acknowledged that surface
water is generally scarce in the arid Southwest and large perennial
streams, even more so. We assume that some streams currently occupied
by the gartersnakes are likely to be designated for nonnative fisheries
because of the scarcity of these aquatic systems in Arizona, the
existing access infrastructure, and the fish communities that currently
reside in larger perennial streams. We are concerned that if large,
perennial streams, which are important occupied habitat for northern
Mexican and narrow-headed gartersnakes (as well as their prey species),
are designated as nonnative sport fisheries in the future, they will be
lost to the gartersnakes, which would negatively affect their recovery
rangewide. Furthermore, we have a high degree of certainty that if any
habitat occupied by either gartersnake is designated strictly as a
nonnative fishery (that includes warm-water, predatory species), that
habitat will no longer possess the values that are important (or
imperative) for species recovery and the value of these areas for
recovery will be largely eliminated. Regarding nonnative species that
are problematic to gartersnakes and which are not considered sport fish
by the AGFD, we look forward to partnering with the AGFD and other
public and private stakeholders in the removal of these species where
they occur, and view this and similar recovery actions as the highest
priority.
Comment 63: The proposed rule discussed at length the issue of
declining native fishes and degradation of aquatic systems in Mexico
but did so without discussing the status of the northern Mexican
gartersnake. This type of argument is an apparent effort to build the
case for listing the subspecies throughout its range based on inferred
effects of the decline of native fish communities and habitat
degradation, despite the fact that clear data for the northern Mexican
gartersnake decline are only available for Arizona and New Mexico.
Our Response: We do not have population studies of northern Mexican
gartersnakes in Mexico. However, we have used the best scientific and
commercial data available. The information shows the status of native
aquatic vertebrates in habitat currently or formerly occupied by the
northern Mexican gartersnake generally correlate to the status of
northern Mexican gartersnakes. We cited examples of how aquatic
ecosystems are adversely affected by leading threats, such as
dewatering or the expansion of harmful nonnative species, can affect
the northern Mexican gartersnake and its native prey species, such as
fish. Native fish comprise an important prey source for northern
Mexican gartersnakes. Gartersnakes need them for nutrition in order to
carry out their life-history functions. We found a significant amount
of information that concluded that native fish communities were
significantly at risk, as documented by declines of many species in
several subbasins across the distribution of the northern Mexican
gartersnake in Mexico. Therefore, when a major source of prey for
northern Mexican gartersnakes becomes rare or disappears entirely, the
gartersnake population will be negatively affected through declines in
the fitness of individuals associated with poor nutrition, stress, and
starvation. Several different factors that are contributing to the
decline in native fish communities include harmful nonnative species,
dewatering of habitat, and pollution of habitat. These stressors also
negatively affect northern Mexican gartersnake populations both
directly and indirectly. Native fish are, therefore, an effective
surrogate for use in determining how threats are acting on individual
northern Mexican gartersnakes and their populations throughout their
distribution in Mexico.
Comment 64: We caution against extrapolation, such as the statement
that there has been a 17-fold increase (since 1961) in the number of
native fish species in Mexico that have been listed by the Mexican
Federal Government as either endangered, facing extinction, under
special protection, or likely extinct. The data cited do not speak to
the status of these native fish species rangewide.
Our Response: We cited references that discuss the status of native
fish in Mexico in our discussion of the status of the northern Mexican
gartersnake in Mexico, and we did not imply those trends represented
their status rangewide.
Comment 65: The Service identified a number of streams or aquatic
communities in Mexico that have been adversely affected by threats such
as declining native fisheries, sedimentation from logging, pollution,
etc. Yet, our observations often point to the inverse in several
headwaters of these identified streams. In other examples, such as the
R[iacute]o Colorado in Sonora, the vicinity of Mexico City, or unnamed
streams draining the Sierra Madre, evidence that these areas were
occupied by the northern Mexican gartersnake or occur within its
distribution was not clearly presented.
Our Response: Much like what has been observed and documented in
the southwestern United States, headwater streams are often less
impacted than the mainstem rivers they feed. This is often because of
the remote nature of these headwaters, which can limit the effect of
human-caused threats (watershed-scale effects increase in the
downstream direction), as well as the presence of natural or man-made
barriers that prevent upstream migration of harmful nonnative species.
Therefore, it may not be appropriate to infer that, simply because a
headwater system is intact, that the same holds true for the system
lower in the watershed. With respect to whether streams identified as
being impacted by various threats in Mexico are within the distribution
of the northern Mexican gartersnake, the references cited were not
presented at a geographic scale fine enough to definitively conclude
that a complete overlap with the distribution of the northern Mexican
gartersnake exists, but rather a portion of the stream overlaps. In
addition, a number of the streams that were called into question by the
AGFD occur at the periphery of the subspecies' range in Mexico, which
is still not precisely understood by the scientific community.
Therefore, we presented the data in a regional context, as evidence
that such threats could affect the gartersnake where they overlap.
Regarding whether the northern Mexican gartersnake ever existed in
the R[iacute]o Colorado in Sonora, there are two verified records from
the Colorado River at Yuma from 1889 and 1890. We assume the species
also occurred downstream into Mexico where suitable

[[Page 38734]]

habitat historically existed. We also presented data on threats to
aquatic habitat in the vicinity of Mexico City. While we agree that
this area represents the extreme southern end of the subspecies'
distribution, we also acknowledge that threats, particularly harmful
nonnative species, can have a larger geographic impact over time.
Lastly, we presented information that suggested that threats may be
affecting streams that drain the Sierra Madre, which in some cases were
not specifically identified by the principal investigators. Considering
that the Sierra Madre represents a large portion of the northern
Mexican gartersnakes' distribution in Mexico, it was appropriate to
include these data in our evaluation in a conservative assumption that
many, if not most, of the streams were historically or currently
occupied by this subspecies.
Comment 66: The New Mexico Department of Game and Fish encourages
an expansion of activities authorized under a special rule under
section 4(d) of the Act to exempt landowners from prohibitions of take
under section 9 of the Act, for those actions that benefit the two
gartersnakes, such as: (1) Enhancement and restoration of native
riparian vegetation and stream structure; (2) control of harmful
nonnative species, such as American bullfrogs and crayfish; (3)
intensive research into the biology of the two species of gartersnake;
and (4) continuing research into captive rearing and repatriation of
the northern Mexican and narrow-headed gartersnakes.
Our Response: We agree that section 4(d) of the Act can provide
important conservation potential in the recovery of these two
gartersnakes, and we appreciate the New Mexico Department of Game and
Fish's willingness to explore such opportunities. We have included a
section 4(d) rule for the northern Mexican gartersnake in this
rulemaking, which addresses the management of livestock tanks on non-
Federal lands. Of the four special rule possibilities offered by the
New Mexico Department of Game and Fish, controlling (removing) harmful
nonnative species is most likely to provide the highest conservation
benefit for northern Mexican and narrow-headed gartersnakes, and we are
interested in looking further into this issue with our cooperators and
stakeholders, such as the New Mexico Department of Game and Fish. In
order to be most effective, such a 4(d) rule would have to be developed
in close coordination with affected agencies, explicitly authorize the
removal of bullfrogs, crayfish, and predatory fish species, and include
precautions to minimize potential harm to affected gartersnake
populations during project implementation. However, at this time, we do
not have sufficient information to allow us to adequately confirm
whether such a 4(d) rule would be necessary and advisable for the
conservation of the species. We can consider such a rule in the future.
Permitting authority for research needs is addressed through the
issuance of section 10(a)(1)(A) permits. With respect to the
enhancement and restoration of native riparian vegetation and stream
structure, where water occurs, the vegetative structure is not viewed
as limiting for gartersnake occupation in most cases. Where water has
been removed from streams by dams, diversions, or groundwater pumping,
correcting these scenarios and returning water to the system would be
construed as a beneficial effect. For any activity not explicitly
addressed in our proposed 4(d) rule that would result in take of either
gartersnake, a section 10 permit would be required to avoid a violation
of section 9 of the Act.

Tribes

Comment 67: In discussing the potential impacts of dams and
reservoirs on resident fish communities, the proposed rule identifies
the San Carlos Reservoir as an example of a reservoir that benefits
harmful nonnative species and, therefore, negatively affects the
northern Mexican and narrow-headed gartersnakes. This statement should
be omitted from the final rule for two reasons. First, the proposed
rule makes this conclusory adverse effect determination without any
support whatsoever. Second, this conclusory determination is
unnecessary to establish that the northern Mexican gartersnake or the
narrow-headed gartersnake should be designated as threatened. In 1924,
Congress enacted the San Carlos Project Act, which authorized the
construction of the Coolidge Dam and the creation of the San Carlos
Reservoir ``for the purpose . . . of providing water for the irrigation
of lands allotted to the Pima Indians on the Gila River Reservation,
Arizona.'' A statement in the proposed rule that the San Carlos
Reservoir adversely affects northern Mexican and narrow-headed
gartersnakes could affect the federally mandated delivery of water to
the Gila River Indian Community. Any impediment to the Gila River
Indian Community's irrigation system threatens the Gila River Indian
Community's agriculture, economy, and most importantly, the survival of
its culture, the value of which is immeasurable.
Our Response: In the final rule, we deleted the reference to the
San Carlos Reservoir as an example of a reservoir within the range of
the gartersnakes that may be benefitting harmful nonnative species,
because there are several other examples. USFWS (2008, pp. 112-131)
provides a complete scientific analysis of the relationship of
reservoirs to resident aquatic communities upstream and downstream,
includes many scientific references that have been incorporated by
reference in this final rule, and comprises the basis for the issuance
of a section 10(a)(1)(B) incidental take permit for the operation of
Horseshoe and Bartlett Reservoirs, in that case. We believe the same
relationships likely are true at San Carlos Reservoir. We look forward
to work with interested parties to identify solutions that meet water
use interests and the conservation needs of listed species.

Public Comments

General
Comment 68: Threats to the gartersnakes are those caused by Federal
and State fish and wildlife management actions, or on Federal lands
that can be dealt with outside of the Act. Approximately 85 percent of
the habitat for the northern Mexican gartersnake is in Mexico. In
Mexico, any activity that intentionally destroys or adversely modifies
occupied northern Mexican gartersnake habitat is prohibited.
Our Response: As stated in the proposed rule, the Act requires us
to make listing determinations based on the five threat factors, singly
or in combination, as set forth in section 4(a)(1) of the Act. The Act
further requires us to make listing determinations solely on the basis
of the best scientific and commercial data available after taking into
account those efforts, if any, being made by any State or foreign
nation, or any political subdivision of a State or foreign nation, to
protect such species, whether by predator control, protection of
habitat and food supply, or other conservation practices within any
area under its jurisdiction. The Act requires us to give consideration
to species that have been designated as requiring protection from
unrestricted commerce by any foreign nation or pursuant to any
international agreement; or identified as in danger of extinction or
likely to become so within the foreseeable future, by any State agency
or by any agency of a foreign nation that is responsible for the
conservation of fish or wildlife or plants.

[[Page 38735]]

A number of existing regulations potentially address issues
affecting the northern Mexican and narrow-headed gartersnakes and their
habitats. However, existing regulations within the range of northern
Mexican and narrow-headed gartersnakes typically address only the
direct take of individuals without a permit and provide little, if any,
protection of gartersnake habitat. Arizona and New Mexico statutes do
not provide protection of habitat and ecosystems. Legislation in Mexico
prohibits intentional destruction or modification of northern Mexican
gartersnake habitat, but neither that, nor prohibitions of take, appear
to be adequate to address ongoing threats. See ``The Inadequacy of
Existing Regulatory Mechanisms'' in the proposed rule for further
information.
Comment 69: There is more recent data on surface activity of
northern Mexican gartersnakes than Rosen (1991, pp. 308-309). More
recent observations indicate radio-tracked snakes were not surface
active 64 percent of the time at Bubbling Ponds and 60 percent of the
time at Tavasci Marsh (upper Verde River) and the middle Verde River.
Our Response: We have updated the discussion under ``Habitat and
Natural History'' for the northern Mexican gartersnake in this final
rule to reflect more recent information, such as the information
provided in the comment.
Comment 70: The proposed rule states that the northern Mexican
gartersnake appears to be most active during July and August, followed
by June and September. Based on recent survey efforts it would probably
be most accurate to state that the species appears to be most active
between May and September.
Our Response: We have updated the discussion under ``Habitat and
Natural History'' for the northern Mexican gartersnake in this final
rule to reflect more recent information, such as the information
provided in the comment.
Comment 71: The proposed rule so broadly describes the species'
physical habitat that it is difficult to determine what types of
riparian, wetland, and terrestrial habitats are important to each of
the gartersnakes and is conflicting with previous characterizations.
Our Response: The habitat descriptions we provide in the proposed
and final rules reflect the current understanding of the types of
habitat that are used by either gartersnake species. The descriptions
appear broad because these gartersnakes, in particular the northern
Mexican gartersnake, can occur in varied ecological settings.
Comment 72: All five of the waters where there are viable
populations of Mexican gartersnakes are already protected and do not
need further protection under the Act. Oak Creek, Tonto Creek, and the
Upper Verde River are protected by spikedace and loach minnow critical
habitat. The San Rafael Valley is protected by The Nature Conservancy
and San Rafael State Park. The Bill Williams River is a National
Wildlife Refuge.
Our Response: We acknowledged in our proposed rule that other
listed species' historic ranges overlap with the historical
distribution of northern Mexican and narrow-headed gartersnakes.
However, as stated above and in the proposed rule, the Act requires us
to make listing determinations based on the five threat factors, singly
or in combination, after taking into account those efforts being made
by any State or foreign nation to protect such species. Management by
Federal or State agencies, or non-governmental organizations does not
necessarily eliminate activities that threaten these subspecies.
Comment 73: The northern Mexican gartersnake in the United States
is not a distinct population segment and does not require protection
under the Act.
Our Response: We did not propose to list either gartersnake as a
distinct population segment. We proposed to list the northern Mexican
and narrow-headed gartersnakes as threatened throughout their ranges.
We also reviewed the best available scientific and commercial
information to conclude that the northern Mexican gartersnake is a
valid subspecies as defined under the Act.
Comment 74: The Service must follow the guidance of Executive Order
13563 of January 18, 2011, concerning making a new Federal rule.
Our Response: Executive Order (E.O.) 13563 reaffirms the principles
of E.O. 12866 while calling for improvements in the nation's regulatory
system to promote predictability, to reduce uncertainty, and to use the
best, most innovative, and least burdensome tools for achieving
regulatory ends. The executive order directs agencies to consider
regulatory approaches that reduce burdens and maintain flexibility and
freedom of choice for the public where these approaches are relevant,
feasible, and consistent with regulatory objectives. E.O. 13563
emphasizes further that regulations must be based on the best available
science and that the rulemaking process must allow for public
participation and an open exchange of ideas. We have developed this
rule in a manner consistent with these requirements.
Comment 75: These gartersnakes are already protected by the New
Mexico Department of Game and Fish.
Our Response: A number of existing regulations potentially address
issues affecting the northern Mexican and narrow-headed gartersnakes
and their habitats. However, existing regulations within the range of
northern Mexican and narrow-headed gartersnakes typically address only
the direct take of individuals without a permit, and provide little, if
any, protection of gartersnake habitat. Arizona and New Mexico statutes
do not provide protection of habitat and ecosystems. Legislation in
Mexico prohibits intentional destruction or modification of northern
Mexican gartersnake habitat, but neither that legislation, nor
prohibitions of take, completely address ongoing threats. See ``The
Inadequacy of Existing Regulatory Mechanisms'' in this final rule for
further information.
Comment 76: The Strategic Water Reserve, managed by the New Mexico
Interstate Stream Commission, already holds and utilizes water rights
to benefit endangered fish and wildlife species in New Mexico. Since
the Service gives strongest weight to statutes because they are
nondiscretionary and enforceable, the New Mexico Interstate Stream
Commission expects the Service to give weight to the Strategic Water
Reserve statute in this final rule.
Our Response: We considered the Strategic Water Reserve managed by
the New Mexico Interstate Stream Commission and have updated the
discussion in the final rule with this new information. However,
collectively, existing regulations within the range of northern Mexican
and narrow-headed gartersnakes are not fully ameliorating ongoing
threats such that the subspecies would not meet the definition of
threatened. See ``The Inadequacy of Existing Regulatory Mechanisms'' in
this final rule for further information.
Comment 77: Contrary to what is implied in the proposed rule, Clean
Water Act section 404 nationwide permits receive rigorous environmental
review by the Corps.
Our Response: We recognize that the Clean Water Act section 404
nationwide permits receive environmental review by the Corps; however,
this process does not appear to be ameliorating ongoing threats to
northern Mexican or narrow-headed gartersnakes such that the subspecies
would not meet the definition of threatened. See ``The Inadequacy of
Existing Regulatory Mechanisms'' in this final rule for further
information.
Comment 78: What is the problem with the management or resources at
the

[[Page 38736]]

Buenos Aires National Wildlife Refuge (BANWR) that makes populations
likely not viable.
Our Response: The abundance of bullfrogs on the BANWR, specifically
in the vicinity of Arivaca Lake and Arivaca Cienega, contributes to the
northern Mexican gartersnake population being categorized as likely not
viable. As stated in our proposed rule, bullfrogs (and other harmful
nonnatives) are a primary threat to the gartersnakes. The presence of a
single juvenile northern Mexican gartersnake was confirmed on the BANWR
in 2000 (Rosen et al. 2001, Appendix I). The observation of this
juvenile suggests that at least some level of reproduction had occurred
and may still be occurring but more recent survey work has not occurred
there. The presence of dense cover probably helps any remaining
northern Mexican gartersnakes to avoid predation.
In recent years, there has been a concerted management effort on
the BANWR to recover the Chiricahua leopard frog in an array of tanks
and their associated drainages, all of which have been designated as
critical habitat for the Chiricahua leopard frog. As a result, it is
likely that any northern Mexican gartersnakes that successfully
immigrate into the central tanks area of the BANWR have an increased
chance of persistence because of improved available habitat and a
stable prey base in an area that is likely free of nonnative predators.
We also expect that dispersing Chiricahua leopard frogs might help
sustain a low-density population of northern Mexican gartersnakes on
the refuge. We consider the northern Mexican gartersnake to be extant
as a low-density population on the BANWR based on historical and recent
records and the abundance of available, suitable habitat and prey
populations in the vicinity of the most recent record. Appendix A
contains additional details on the status of the northern Mexican
gartersnake at this and other refuges.
Comment 79: What is the relationship of the Arizona Department of
Water Resource laws and the proposed listing of the two gartersnakes?
For New Mexico, the New Mexico State Engineer indicated that any person
in New Mexico can apply to the State Engineer for a permit for the
lease of a valid existing water right to augment or maintain stream
flow for the beneficial use of fish and wildlife habitat, maintenance
or restoration. Further, permits for the permanent transfer of water
rights for such purposes have already been granted to the New Mexico
Interstate Stream Commission. Both the Strategic Water Reserve option
and the leasing option retain a water right's original priority date.
Our Response: Existing water laws in Arizona and New Mexico may not
be fully adequate to protect gartersnake habitat from the dewatering
effects of groundwater withdrawals. New Mexico water law now includes
provisions for instream water rights to protect fish and wildlife and
their habitats. Arizona water law also recognizes such provisions;
however, because this change is relatively recent, instream water
rights have low priority and are often never fulfilled because more
senior diversion rights have priority. With respect to New Mexico, we
have updated the discussion on New Mexico water rights laws in the
final rule to correct any inaccuracies.
Comment 80: The information in Table 1 of the proposed rule does
not match the information on page 41515. Page 41515 states that a
former large, local population of northern Mexican gartersnakes at the
San Bernardino National Wildlife Refuge has experienced correlative
decline of leopard frogs and are now thought to occur at very low
population density or may be extirpated. Table 1 states likely not
viable.
Our Response: We consider gartersnake populations with very low
population densities, and thus at higher risk of extirpation, such as
the one at San Bernardino National Wildlife Refuge, to be likely not
viable. While the population could already be extirpated, we did not
have sufficient information to categorize it as likely extirpated and
so called it likely not viable.
Surveys and Monitoring
Comment 81: The proposed rule states that the northern Mexican
gartersnake has declined significantly in the last 30 years, but then
goes on to state that there are several areas where the species was
known to occur but has received no or very little survey effort in the
past decades.
Our Response: We based our conclusions on the best scientific and
commercial data available at the time of listing. We have concluded
that, in as many as 24 of 29 known localities in the United States (83
percent), the northern Mexican gartersnake population is likely not
viable and may exist at low population densities that could be
threatened with extirpation or may already be extirpated. In most
localities where the species may occur at low population densities,
existing survey data are insufficient to verify extirpation. Only five
populations of northern Mexican gartersnakes in the United States are
considered likely viable.
Comment 82: The Service assumes the populations at Whitewater Creek
and Middle Fork Gila River are likely deteriorated or have been
severely jeopardized after the Whitewater-Baldy Complex Fire, but
subsequent survey data have not been collected. In the absence of
subsequent survey data, the Service lacks information to supports its
assumption that the narrow-headed gartersnake populations have
deteriorated. Further, we understand that some of the northern Mexican
gartersnakes discovered in the Gila National Forest in June 2013 were
found precisely in Whitewater Creek. Among the discovered snakes were
young males and at least one viable reproducing female, suggesting that
the populations of northern Mexican gartersnakes are living and
reproducing in the area. The discovery of a reproducing population of
northern Mexican gartersnakes in this area suggests that populations of
narrow-headed gartersnakes may not be as likely deteriorated as the
Service suggests.
Our Response: The proposed rule states that the status of those
populations has likely deteriorated as a result of subsequent declines
in resident fish communities due to wildfires followed by heavy ash and
sediment flows, resulting fish kills, and the removal of snakes.
Immediately after the Whitewater-Baldy Complex Fire, but before the
subsequent monsoon, we were actively working with other agencies and
species experts on assessing the likely damage to the resident fish
community and planning salvage operations for narrow-headed
gartersnakes. As stated in Appendix A (available at http://www.regulations.gov, Docket No. FWS-R2-ES-2013-0071), populations are
thought to remain extant at Whitewater Creek and Middle Fork Gila
River, but in the short to mid term we anticipate the density of the
narrow-headed gartersnake population to be low due to the Whitewater-
Baldy Complex Fire. These sites may rebound in the mid to long term
when subbasin conditions stabilize and fish begin to recolonize the
stream or are otherwise reintroduced through restoration efforts. See
``High-Intensity Wildfires and Sedimentation of Aquatic Habitat''
section of the final rule for additional information. The best
available scientific and commercial data indicated that high-intensity
wildfires have the potential to eliminate gartersnake populations
through a reduction or loss of their prey base.
Northern Mexican gartersnakes have never been documented in
Whitewater

[[Page 38737]]

Creek, but were rediscovered in the Gila River in 2013.
Comment 83: Haney et al. (2008, p. 61) declared the northern
Mexican gartersnake as nearly lost from the Verde River, but also
suggested that diminished river flow may be an important factor. Given
the multiple recent detections of northern Mexican gartersnakes along
the upper and middle Verde River, this statement does not seem relevant
to include in the proposed rule.
Our Response: More recent population status data for the northern
Mexican gartersnake for the Verde River were preliminary and
unpublished at the time the proposed rule was drafted. These newer data
have been incorporated into the final rule and Appendix A.
Comment 84: Is a consistent survey protocol being followed each
year? Is data collected from different surveys comparable? Without
scientific survey protocol implemented consistently for at least 10
years, there can be no real evidence of population trends.
Our Response: There is currently no accepted protocol for northern
Mexican or narrow-headed gartersnake surveys; however, some
investigators have attempted to revisit locations where others have
surveyed in the past in an attempt to establish population trends.
Variability in survey design and effort makes it difficult to compare
population sizes or trends among sites and between sampling periods.
For each of the sites discussed in Appendix A, we have attempted to
translate and quantify search and capture efforts into comparable units
(i.e., person-search hours and trap-hours) and have conservatively
interpreted those results. Where population trends have been
established, they have been reported and reflect significant declines
in both species.
Comment 85: The Service has failed to survey, analyze data, and
incorporate the effects of the thousands of livestock tanks and other
impoundments that have been constructed in recent times that are now
occupied by the narrow-headed and northern Mexican gartersnakes. These
stock tanks and manmade impoundments offer the best opportunity for
refugia for the narrow-headed and northern Mexican gartersnakes and
could prove to be very important for the future survival of these
gartersnakes, as well as the Chiricahua leopard frog. Given the
quantity of tanks and other impoundments constructed in the last 50
years, the number of these structures that are used by the gartersnakes
could be substantial, and, therefore, the potential population count
for the species could be significantly higher than speculated.
Our Response: Surveys of every stock tank that could occur within
the distribution of both gartersnake species have not been done. The
Act requires that we base our evaluation on the best scientific and
commercial information available. We agree that well-managed stock
tanks represent conservation and recovery opportunities for the
northern Mexican gartersnake and have consequently developed a rule
under section 4(d) of the Act that exempts otherwise unauthorized take
of northern Mexican gartersnakes from livestock use or maintenance of
stock tanks on non-Federal lands. Stock tanks are not considered
suitable habitat for narrow-headed gartersnakes, and the species has
never been reported using a stock tank.
Harmful Nonnative Species and Other Threats
Comment 86: No information is provided describing San Carlos
Reservoir operations and their effects on nonnative and native aquatic
species, whether there are or ever has been gartersnakes in or near the
San Carlos Reservoir and the status of any nonnative fish populations
on the Gila River at San Carlos Reservoir. This is not based on the
best available science.
Our Response: Distribution data strongly suggest that northern
Mexican and narrow-headed gartersnakes historically occurred along the
middle Gila River, as this was formerly a major perennial river with
several known populations both upstream and within numerous
tributaries, with suitable habitat, and a robust native prey base.
Post-construction of the San Carlos Reservoir, survey data are limited.
Thus it remains difficult to ascertain the current status of
gartersnake populations upstream, downstream, or within the reservoir
itself. As far as the effect of the reservoir on the up- or downstream
aquatic community, similar analysis have been performed for the
Horseshoe and Bartlett Reservoirs, which resulted in the issuance of a
section 10(a)(1)(B) permit for the incidental take of native fish
species, the lowland leopard frog, the northern Mexican gartersnake,
and the narrow-headed gartersnake. USFWS (2008, pp. 112-131) supports
our rationale as to how adverse effects to native aquatic species occur
from the presence and operation of reservoirs in the Gila River basin
of Arizona.
Comment 87: In the proposed rule, the Service refers to the
potential development of the Hooker Dam on the mainstem Gila River
above Mogollon Creek and below Turkey Creek. The U.S. Bureau of
Reclamation has abandoned any intention of completing Hooker Dam, and
its reference as a possible future project should be deleted from the
final rule.
Our Response: We have confirmed with the U.S. Bureau of Reclamation
that there are no current plans to develop Hooker Dam, and it is not
referenced in the final rule.
Comment 88: Barriers to fish movement out of Roosevelt Lake should
be acknowledged in the final rule. The Roosevelt Dam on the Salt River
serves as an effective barrier to upstream fish movement, which would
prevent nonnative fish from moving upstream.
Our Response: In the final rule, we added a statement in our
discussion of dams to reflect this fact.
Comment 89: The proposed rule states that additional land and water
use activities along Tonto Creek and the Salt River, including areas
upstream of Roosevelt Lake, contribute to the persistence of nonnative
aquatic species that negatively affect the gartersnakes. However, the
Tonto Creek exhibits seasonally intermittent flows in the lower reaches
below Gun Creek. Sections of dry streambed serve as a barrier to
upstream fish migration. Further, high flow events have been documented
to remove nonnative species by flushing them downstream. In addition,
nonnative spiny-rayed fish are not typically motivated to migrate
upstream out of lakes because they prefer lentic over lotic habitats.
Our Response: Connectivity between otherwise spatially intermittent
reaches is established during seasonal periods of snowmelt runoff as
well as during medium- to large-scale flood pulses. These opportunities
contribute to the distribution of harmful nonnative fish throughout
Tonto Creek, as demonstrated in fish survey data that has been
collected, reviewed, and reported in Appendix A. With respect to
whether harmful nonnative fish are ``not typically motivated to migrate
upstream out of lakes,'' the data are lacking to clearly defend this
statement, especially when reservoir levels decrease, which lessens the
amount of space available in reservoirs, which may in turn trigger
dispersal or movement behaviors in harmful nonnative fish that are
known to be territorial by their nature. Additionally, the simple
presence of otherwise ``lentic'' nonnative species in lotic habitat
upstream of reservoirs to which they are hydrologically connected,
suggests this perceived preference may not be altogether true; green
sunfish are an excellent example.

[[Page 38738]]

Comment 90: A number of other activities (both present and
historical) in the area of Tonto Creek and the Salt River in the
vicinity and upstream of Roosevelt Lake are likely contributing to the
decline of gartersnakes and the aquatic and riparian habitat on which
they depend. Specifically, a historical stocking program of nonnatives,
manmade impoundments within the Tonto Creek floodplain, and other
activities identified in the proposed rule, such as groundwater
pumping, flood control projects, urbanization, and livestock grazing.
The major activities reducing flows and dewatering habitat are
occurring upstream of Roosevelt Lake. A bridge is proposed over Tonto
Creek, and 320 to 640 residences are projected to be built on the east
side of Tonto Creek, under the Gila County's comprehensive plan. This
would increase water and recreational use. The U.S. Forest Service's
Motorized Travel Management Plan has the potential to open 2,567 miles
(4,131 km) of road to high clearance vehicles and 967 miles (1,556 km)
to passenger vehicles. The Tonto National Forest's Salt River
Allotments Vegetative Management Plan would allow continued grazing on
more than 275,000 acres (111,000 ha) along the Upper Salt River.
Potential impacts to the narrow-headed gartersnake are noted, and the
potentially suitable habitat for the northern Mexican gartersnake that
occurs along the Salt River is the same area that the USFS proposes for
grazing.
Our Response: We agree that numerous threats are affecting the
status of both gartersnake species in Tonto Creek. The final rule (see
``Altering or Dewatering Aquatic Habitat'') references land use
activities in this area that we consider as having an effect on
resident gartersnake populations.
Comment 91: The Service's generalized and unsupported assertions
that all dams have the same impacts on gartersnakes should be removed
from the final rule. The ``Altering or Dewatering Aquatic Habitat''
section of the proposed rule is not supported by any citations
regarding water level fluctuations in reservoirs and cross-section
profiles of a reservoir. This section should provide citations and
recognize the diversity of the various types of reservoirs.
Statements regarding the effect of Roosevelt Lake on gartersnake
populations in Tonto Creek and the upper Salt River lack any scientific
or technical basis and should be removed from the final rule. Other
than referencing a biological opinion (USFWS 2008, pp. 112-131), the
proposed rule provides no basis for the assertion that harmful
nonnative fish are moving upstream out of Roosevelt Lake into Tonto
Creek or the Salt River. Since the biological opinion in 2008,
monitoring conducted under the Horseshoe-Bartlett Habitat Conservation
Plan has been implemented to document the movement of nonnative fish
upstream of the Horseshoe Reservoir into the Verde River, and reaches
of the Verde River have been sampled, and to date no evidence of fish
movement has been detected.
Our Response: We agree that not every dam has the same effect on
the stream on which it is located. We disagree that our treatment of
the effects of dams on occupied lotic habitat are unsupported. The
identified section discusses general effects of dams, based on
available literature, as a suite of effects common in all instances in
various degrees. This same section also includes referenced discussion
of specific dams or diversions and their specific effects on certain
gartersnake populations. The relationship of the cross-sectional
profiles and water level fluctuations of reservoirs to benefits to
harmful nonnative fish communities was an integral part of a 4-year
evaluation, in close collaboration with the operators of those
reservoirs themselves, dedicated to the development of the habitat
conservation plan for Bartlett and Horseshoe Reservoirs on the Verde
River. We incorporated by reference this exhaustive analysis, which
used the best available data to date (see SRP 2008, entire; USFWS 2008,
pp. 112-131).
We are not aware of any analysis afforded specifically to the
potential benefits of Roosevelt Dam operations to the sustainment or
production of harmful nonnative fish populations in Roosevelt Lake,
Tonto Creek, or the Salt River, upstream of Roosevelt Dam. The
exhaustive analysis of these effects as they are attributed to
similarly sized dams and reservoirs on the Verde River system
referenced immediately above represent the most applicable, current,
and robust analyses to date. We do note that Roosevelt Lake does not
fluctuate as much as does Horseshoe Reservoir on the Verde River and,
therefore, most likely provides greater benefits to the resident
harmful nonnative fish community. With respect to fish sampling data
from the implementation of the Horseshoe and Bartlett HCP, sampling
events do not occur during the most appropriate time to capture
movement of fish out of the reservoir (during periods of rapid drawdown
or during drawdown after periods of prolonged storage) and thus may not
adequately capture these relationships. Additionally, more fish have to
be marked in the reservoir to create better opportunities for their
discovery elsewhere in the watershed. Lastly, recent northern Mexican
gartersnake records have been reported immediately upstream, if not
adjacent to, Roosevelt Lake, which affirms that adverse effects from
harmful nonnative species that occur in Roosevelt Lake present a
demonstrable threat to that population of northern Mexican
gartersnakes.
Comment 92: The proposed rule states that, on the upper Verde
River, native species dominated the total fish community at greater
than 80 percent from 1994 to 1996, before dropping to approximately 20
percent in 1997 and 19 percent in 2001. This statement points to
specific empirical data regarding declining native fish species in the
upper Verde River watershed, but there is no reference to verify the
sources, context, or specific species to which it is referring.
Our Response: Rinne et al. (2005, pp. 6-7) contains a discussion of
shifting fish communities in the Verde River, and Bonar et al. (2004,
entire) contains a detailed analysis of the role harmful nonnative
fishes have had on the native fish community of the Verde River. Also
Bonar et al. (2004, pp. 6-7) summarizes this information.
Comment 93: If it is true that the narrow-headed and northern
Mexican gartersnakes have declined substantially in the United States
and the decline of these species is most likely due to the introduction
of nonnative predator and competitor species as stated in the 2006 and
2008 status reports, then the listing of these species as threatened
will do little for their recovery.
Our Response: As stated in the proposed rule, conservation measures
provided to species listed as endangered or threatened species under
the Act include recognition, recovery actions, requirements for Federal
protection, and prohibitions against certain practices. Recognition of
conservation needs of species through listing under the Act results in
public awareness and conservation by Federal, State, tribal, and local
agencies, private organizations, and individuals. The Act encourages
cooperation with the States and recovery plans will identify recovery
actions that will benefit listed species. See ``Available Conservation
Measures'' in this final rule for additional information on this
subject.
Comment 94: Local persons are catching gartersnakes in contests and
seeing how many they can kill to win the contest.
Our Response: We have no information to indicate that collection of

[[Page 38739]]

gartersnakes is a significant threat. However, if this activity is
occurring, it will be considered a prohibited take of the species, once
listed.
Comment 95: The Service should take into account the adverse
effects of the past Federal land management agency burning programs and
the recent wildfires that have occurred in the narrow-headed and
northern Mexican gartersnakes home ranges. Closer scrutiny of the
current Federal land management burning program, and lack of a coherent
thinning and logging program, coupled with a better understanding of
the effects of the recent large wildfires, should be completed in order
to focus future protection and restoration efforts towards what is
truly causing the decline of the narrow-headed and northern Mexican
gartersnakes. There is no benefit to immediately listing these
gartersnakes as threatened when there is doubt concerning the current
and future potential cause for decline of the species.
Our Response: In the proposed rule, we discuss effects of recent
fire management policies on aquatic communities in Madrean Oak Woodland
biotic communities in the southwestern United States. Existing wildfire
suppression policies intended to protect the expanding number of human
structures on forested public lands have altered the fuel loads in
these ecosystems and increased the probability of high-intensity
wildfires (Rinne and Neary 1996, p. 143). The historical actions
affecting a species are considered as background in our assessment in
terms of their contribution to the present-day status of these species.
However, in evaluating the status of the species, the Act requires that
we assess present and future factors that may threaten the species. If
past actions are continuing threats, these threats are evaluated under
the five-factor analysis. If these past actions are not continued
factors, then these actions are not assessed in the analysis of the
future status because they are no longer present or future factors
threatening the species.
Section 7(a)(1) of the Act requires that all Federal agencies shall
utilize their authorities in furtherance of the purposes of the Act by
carrying out programs for the conservation of endangered and threatened
species. Section 7(a)(2) of the Act requires Federal agencies to ensure
that activities they authorize, fund, or carry out are not likely to
jeopardize the continued existence of the species or destroy or
adversely modify its critical habitat. If a Federal action may affect a
listed species or its critical habitat, the responsible Federal agency
must enter into formal consultation with us. Lastly, while we
acknowledge in the proposed and final rules that large wildfires can
have significant adverse effects on gartersnake populations and their
prey base (in particular for narrow-headed gartersnakes), the
literature is clear that harmful nonnative species pose the most
significant threat to both species, rangewide, through a variety of
ecological mechanisms.
Comment 96: The proposed rule states that Cavazos and Arriaga
(2010, entire) found that average temperatures along the Mexican
Plateau in Mexico could rise by as much as 1.8[emsp14][deg]F (1 [deg]C)
in the next 20 years and by as much as 9[emsp14][deg]F (5 [deg]C) in
the next 20 years, according to their models. This statement is
confusing because the reference cites two different temperatures for
the same timeframe in the same area.
Our Response: Climate models often report a range of scenarios, as
was the case in this instance. We did revise that language for clarity.
However, we expect precipitation and temperature trends, as modeled
under future climate change projections, to increase regional aridity
in Mexico within the distribution of the northern Mexican gartersnake,
which is expected to place additional drought stress on stream flow and
reduce the permanency of cienegas, marshes, and livestock tanks. As
streams dry, they will become unsuitable as habitat for this
gartersnake and its prey base over the next several decades.
Comment 97: We request that the Service provide clarification and
more information regarding the presence of mercury in Tonto Creek and
likely sources of this substance. No study was cited for the claim that
mercury appears to be bioaccumulating in fish in the lower reaches of
the Tonto Creek, only a personal communication with Arizona Department
of Environmental Quality. The information in the proposed rule is
contrary to the Arizona Department of Environmental Quality's 2011
report on ``Fish Consumption Risk Analysis for Tonto Creek, Arizona.''
Specifically, desert suckers have the fourth highest mercury levels,
not the second.
Our Response: We updated this discussion under ``Environmental
Contaminants'' in the final rule to include data reported by ADEQ
(2011, entire), as well as other information, and acknowledged in the
proposed and final rules that no study on the bioaccumulation of
mercury in resident gartersnakes has been implemented that we are aware
of. The suggestion that bioaccumulation of mercury could be occurring
is based on the accepted scientific premise regarding the toxicology of
mercury in ecosystems and its ability to increase its concentration in
tissue with increasing trophic orders. Gartersnakes are tertiary
consumers and, therefore, are expected to bioaccumulate contaminants
such as mercury in their tissues.
Comment 98: The term excessive sedimentation as used in the
proposed rule is open to interpretation and should be defined to
eliminate unnecessary waste of resources of the Service in defending
its finding. Any large storm event that changes the morphology of a
channel or adjoining riparian habitat can be used to control all human
activities in that they can be construed to have caused the resulting
flooding.
Our Response: It is beyond our scope to quantitatively define what
level of sedimentation is excessive for every stream. However, we agree
that flood pulses naturally liberate sediment in arid southwestern
watersheds. In the absence of absolute values or metrics, we consider
excessive sedimentation that level in which resident gartersnake prey
species or gartersnakes themselves are not able to adequately carry out
life-history functions such as feeding, sheltering, or breeding as a
result of the effects of sedimentation. Arizona and New Mexico also
have turbidity or total dissolved solid standards for surface water,
which can also be used as a reference.
Comment 99: The proposal to list is based on the false premise that
riparian habitats are declining in the Southwest (see Webb et al.
2007).
Our Response: A comprehensive analysis of the scientific literature
supports our evaluation of the status of habitat where these
gartersnakes historically or currently occur.
Comment 100: We request the Service clarify the year of reference
in their projection that annual precipitation amounts in the
southwestern United States may decrease by 10 percent by the year 2100.
Our Response: Overpeck (2008, entire) is a presentation where this
information was originally presented although much of the information
used in Overpeck (2008) was from the Intergovernmental Panel on Climate
Change (IPCC 2007). We presume the year(s) of reference may be 2007-
2008 because that is the time period when the reference was created.
Comment 101: The Service should acknowledge the uncertainty of
broad predictions associated with climate change in their final rule.
Our Response: In our analyses, we use our expert judgment to weigh
relevant information, including uncertainty, in

[[Page 38740]]

our consideration of various aspects of climate change and their
predicted effects on northern Mexican and narrow-headed gartersnakes.
Comment 102: The Service states that wildfire is a threat to the
narrow-headed gartersnake throughout its range. However, the Service
also discusses the Dry Lakes Fire of 2002, which resulted in a complete
fish kill in Turkey Creek. Turkey Creek has since been recolonized by
native fish species almost exclusively. Consequently, it is conceivable
that snakes that survived a period without fish might then find
themselves in an environment better suited to their needs (i.e., devoid
of nonnative species) than before the fire. Further, the Service states
that both species of gartersnakes are somewhat resilient to physical
habitat disturbance where harmful nonnative species are absent.
Our Response: We agree that if enough individual narrow-headed
gartersnakes can survive the post-fire period of ash flows and fish
kills, without risking genetic bottlenecking within the population,
that an ensuing native-only fish community would be highly beneficial.
However, field research has proven that over time and without a barrier
to upstream movement, harmful nonnative fish ultimately make their way
back into these streams and negatively affect the native aquatic
community. Therefore, any plausible post-fire benefits to surviving
narrow-headed gartersnakes are most likely short-lived.
Information Quality and Quantity
Comment 103: Personal communications of a graduate student are a
weak basis for determining the current status of the narrow-headed
gartersnake in New Mexico (or, as found in other citations, the effects
of the Whitewater Baldy fire on the narrow-headed and northern Mexican
gartersnakes). Personal communications or gray literature are not
subject to the necessary vigorous peer review and substantiation that
would meet the Act's requirements for science-based or commercial data.
Our Response: As required by the Act, we based our proposal and
this final rule on the best available scientific and commercial data.
Our Policy on Information Standards Under the Act (published in the
Federal Register on July 1, 1994 (59 FR 34271)), the Information
Quality Act (section 515 of the Treasury and General Government
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)),
and our associated Information Quality Guidelines, provide criteria,
establish procedures, and provide guidance to ensure that our decisions
are based on the best scientific data available. Information sources
may include the recovery plan for the species, articles in peer-
reviewed journals, conservation plans developed by States and counties,
scientific status surveys and studies, biological assessments, other
unpublished materials, or experts' opinions or personal knowledge. We
receive and use information on the biology, ecology, distribution,
abundance, status, and trends of species from a wide variety of sources
as part of their responsibility to implement the Act. This information
includes status surveys, biological assessments, and other unpublished
material (that is, ``gray literature'') from State natural resource
agencies and natural heritage programs, Tribal governments, other
Federal agencies, consulting firms, contractors, and individuals
associated with professional organizations and higher educational
institutions. We also use published articles from juried professional
journals. The reliability of the information contained in these sources
can be as variable as the sources themselves. As part of their routine
activities, our biologists are required to gather, review, and evaluate
information from these sources prior to undertaking listing, recovery,
consultation, and permitting actions.
Comment 104: If science-based and commercial data are not available
for populations, then any projections for populations in the United
States based on northern Mexican gartersnake populations would
necessarily be speculative.
Our Response: The Act requires that we use the best scientific and
commercial data available at the time of listing. Appendix A (available
at http://www.regulations.gov, Docket No. FWS-R2-ES-2013-0071)
discusses such considerations as the physical condition of habitat, the
composition of the aquatic biological community, the existence of
significant threats, and the length of time since the last known
observation of the subspecies in presenting rationale for determining
occupancy status at each locality.
Comment 105: The Service's statement that as much as 90 percent of
historical populations in the United States either occur at low
densities or are extirpated due to the total number of stream miles
that are now permanently dewatered appears to be pure speculation and
not supported by factual data. It is doubtful that an accurate
accounting exists of stream miles in the United States that
historically supported the northern Mexican gartersnakes, and it is
further doubtful that an accurate accounting exists of stream miles
that historically were perennial and are now ephemeral. This kind of
information would require dealing with specific time periods and
specific stream reaches, which is not offered in the statement.
Our Response: This assessment is based on the best available
scientific and commercial data for northern Mexican gartersnakes in the
United States. Museum records and habitat requirements indicate the
species technically occurred in every county and nearly every subbasin
within Arizona. We used GIS and information on threats and status of
historical populations as well as habitat preferences, in arriving at
the 90 percent figure, which we consider to be reasonably accurate
given the information available. Considering the large number of stream
miles that were historically perennial within the historical
distribution of the northern Mexican gartersnake in Arizona that are
now ephemeral, and the degraded status of populations as a result of a
multitude of threats, our presentation of the data represents the most
accurate possible.
Effect of Listing on Non-Federal Interests
Comment 106: The language in the proposed rule that lists
activities which could result in the reduction of the distribution or
abundance of important gartersnake prey species, as well as reduce the
distribution and amount of suitable physical habitat on a regional
landscape for the gartersnakes themselves, is an invitation for many
organizations to sue the Service for allowing activities deemed to
affect the gartersnake on a regional landscape basis. This gives the
gartersnakes' prey species endangered status under the Act also.
Our Response: The Act and its implementing regulations set forth a
series of general prohibitions and exceptions that apply to all
wildlife listed under the ESA. The prohibitions of section 9(a)(2) of
the Act make it illegal for any person subject to the jurisdiction of
the United States to take (includes harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, or collect; or to attempt any of these),
import, export, ship in interstate commerce in the course of commercial
activity, or sell or offer for sale in interstate or foreign commerce
any listed species.
We may issue permits to carry out otherwise prohibited activities
involving endangered and threatened wildlife species under certain

[[Page 38741]]

circumstances. A permit must be issued for the following purposes: For
scientific purposes, to enhance the propagation or survival of the
species, and for incidental take in connection with otherwise lawful
activities.
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a proposed
listing on proposed and ongoing activities within the range of species
proposed for listing. See the Available Conservation Measures section
in the proposed rule for a list of activities that could potentially
result in a violation of section 9 of the Act. Lastly, it is important
to note that our emphasis for the recovery of listed species is to
assess and improve ecosystem function as a basic tenant of conservation
biology; this includes the physical habitat and biological community
where a listed species occurs. This management construct is not unique
to these gartersnakes.
Comment 107: Listing will hinder conservation efforts of the New
Mexico Department of Game and Fish.
Our Response: We disagree. Once these species are listed, funding
for recovery actions may be more accessible from a variety of sources,
including Federal grants, State programs, and cost-share grants for
non-Federal landowners, the academic community, and nongovernmental
organizations. In addition, pursuant to section 6 of the Act, the
States of Arizona and New Mexico will be eligible for Federal funds to
implement management actions that promote the protection or recovery of
the narrow-headed and northern Mexican gartersnakes.
Section 4(d) Rule
Comment 108: If the Service decides to list the species, then we
recommend the development of a 4(d) rule to exempt landowners from
prohibitions of take under section 9 of the Act for those actions
benefitting the two species of gartersnakes, as was the case for the
Chiricahua leopard frog.
Our Response: We proposed a special rule for the northern Mexican
gartersnake under section 4(d) of the Act that would exempt take of
northern Mexican gartersnakes as a result of livestock use at or
maintenance of livestock tanks located on non-Federal lands, and a
final 4(d) rule is incorporated into this final rule. We do not have
the necessary information at this time to determine that general
actions benefitting the two species of gartersnakes would meet the
standard of a 4(d) rule to be necessary and advisable for the
conservation of the species. We would need more specific information
regarding the actions under consideration.
Comment 109: Concerned with the language in the proposed 4(d) rule,
which states: ``Incidental take of northern Mexican gartersnakes is not
a violation of section 9 of the Act if it occurs from any other
otherwise legal activities involving northern Mexican gartersnakes and
their habitat that are conducted in accordance with applicable State,
Federal, tribal, and local laws and regulations.'' This language could
be interpreted to allow incidental take for any activity in the snake's
habitat as long as the activity was legal. We suggest the following
language: (3) What activities are allowed? Incidental take of northern
Mexican gartersnakes is not a violation of section 9 of the Act if it
occurs from (a) otherwise legal activities involving northern Mexican
gartersnakes and their habitat that are conducted in accordance with
applicable State, Federal, tribal, and local laws and regulations, and
(b) such activities occurring in northern Mexican gartersnake habitat
pertain to maintenance activities at livestock tanks located on
private, State, or tribal lands. A livestock tank is an existing or
future impoundment in an ephemeral drainage or upland site constructed
primarily as a watering site for livestock.
Our Response: We have amended the 4(d) rule, in the final rule, to
reflect this recommendation. We revised the language in the 4(d) rule
to better describe our intention for the rule to exempt only activities
related to the construction, use, and maintenance of stock tanks for
livestock watering. These changes did not alter the scope of the 4(d)
rule.

Determination--Standard for Review

Section 4 of the Act (16 U.S.C. 1533), and its implementing
regulations at 50 CFR part 424, set forth the procedures for adding
species to the Federal Lists of Endangered and Threatened Wildlife and
Plants. Under section 4(a)(1) of the Act, we may list a species based
on (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) Overutilization for
commercial, recreational, scientific, or educational purposes; (C)
Disease or predation; (D) The inadequacy of existing regulatory
mechanisms; or (E) Other natural or manmade factors affecting its
continued existence. Listing actions may be warranted based on any of
the above threat factors, singly or in combination.
Until recently the Service has presented its evaluation of
information under the five listing factors in an outline format,
discussing all of the information relevant to any given factor and
providing a factor-specific conclusion before moving to the next
factor. However, the Act does not require findings under each of the
factors, only an overall determination as to the species' status (for
example, threatened, endangered, or not warranted). Ongoing efforts to
improve the efficiency and efficacy of the Service's implementation of
the Act have led us to present this information in a different format
that we believe leads to greater clarity in our understanding of the
science, its uncertainties, and our application of our statutory
framework to that science. Therefore, while the presentation of
information in this rule differs from past practice, it differs in
format only. We have evaluated the same body of information we would
have evaluated under the five listing factors outline format in the
past, we are applying the same information standard, and we are
applying the same statutory framework in reaching our conclusions.

Determination for Northern Mexican Gartersnake

The Act defines an endangered species as any species (or
subspecies) that is ``in danger of extinction throughout all or a
significant portion of its range'' and a threatened species as any
species ``that is likely to become endangered throughout all or a
significant portion of its range within the foreseeable future.'' We
have carefully assessed the best scientific and commercial information
available regarding the status of the northern Mexican gartersnake and
have determined that this subspecies meets the definition of a
threatened subspecies under the Act based on its current status and the
future threats to the subspecies.
We find that the northern Mexican gartersnake is not currently in
danger of extinction because it remains extant in most of the subbasins
where it historically occurred, and its known threats have not yet
resulted in substantial range reduction or a substantial number of
population extirpations to put the subspecies on the brink of
extinction. Currently, only 6 former United States populations were
found to be likely extirpated, and 29 populations are believed to
remain extant. Therefore, we determined that the present risk of
extinction is not

[[Page 38742]]

sufficient to warrant a finding of endangered under the Act.
However, the northern Mexican gartersnake has undergone declines in
its abundance, and we found only 5 of 29 current populations in the
United States are likely viable into the foreseeable future, or what we
consider to be the next several decades. While we are not able to
quantify the status of all populations in Mexico, based on the threats
and the declining status of aquatic communities there, we assume a
similar status in the Mexican portion of its range. We expect the
status of the subspecies will decline in the next several decades
mainly as a result of the continuing and expanding impacts of harmful
nonnative species and the increasing nature of threats associated with
human population growth and climate change. As the effects of these
threats escalate on the landscape (as summarized below), we expect that
additional populations will be extirpated, and that the northern
Mexican gartersnake will be in danger of extinction in the foreseeable
future.
In our review of the best available scientific and commercial
information, we found that aquatic ecosystems upon which the northern
Mexican gartersnake relies have been significantly degraded by the
introduction and proliferation of harmful nonnative species (Factors C
and E). Harmful nonnative species (mainly predatory fishes, bullfrogs,
and crayfish) have been intentionally released or have naturally moved
into nearly every subbasin throughout the range of the northern Mexican
gartersnake. This has resulted in widespread declines in native fish
and amphibian communities, which are integral to the continued survival
of the northern Mexican gartersnake because they serve as their primary
food source. Harmful nonnative species have indirectly impacted
northern Mexican gartersnakes by predation on their prey base (native
fish and amphibians) and have directly impacted them through preying on
young gartersnakes (Factor B), which impacts gartersnake populations
through declines in the recruitment of young snakes into the
reproductive age class. In combination, these factors have resulted in
population declines, range restrictions within subbasins, and some
population extirpations. We found the threat related to harmful
nonnative species to be the most significant and pervasive of all
threats affecting the subspecies.
Additional threats to the habitat of northern Mexican gartersnakes
include water use activities, climate change, and drought (Factor A).
Dams, water diversions, flood-control projects, and groundwater pumping
have dewatered entire reaches of historically occupied habitat in some
areas. The rapidly growing human population in the arid southwestern
United States, combined with a drought-limited supply of surface water,
will further increase future needs for water supplies and associated
infrastructure (dams, diversions, and groundwater pumping) that will
also contribute to habitat losses in the next several decades. Losses
of aquatic habitats are also expected due to the impacts of climate
change, which includes increased aridity, lower annual precipitation
totals, lower snow pack levels, higher variability in flows (lower low-
flows and higher high-flows) in the southwestern United States and
northern Mexico. The population-level effect of factors that modify or
destroy the physical attributes of gartersnake habitat is amplified
when they act in the presence of harmful nonnative species.
Other factors act in combination to negatively affect the northern
Mexican gartersnake, including mismanaged or unmanaged livestock
grazing (Mexico; Factor A); road construction, use, and maintenance
(Factor A); adverse human interactions (Factor E); environmental
contaminants (Factor A); erosion control techniques (Factor A); and
possible competitive pressures from sympatric species (Factor E). These
threats occur within the distribution of this gartersnake and
contribute to further population declines or extirpations where
gartersnakes already occur at low population densities due to the
impacts of harmful nonnative species. The existing regulatory
mechanisms currently in place (Factor D) do not target the conservation
of this subspecies or its habitat in the United States or Mexico.
Therefore, on the basis of the best available scientific and
commercial information, we find the northern Mexican gartersnake is
likely to become in danger of extinction throughout all of its range
within the foreseeable future, and we are listing the northern Mexican
gartersnake as a threatened subspecies in accordance with sections
3(20) and 4(a)(1) of the Act.

Determination for Narrow-Headed Gartersnakes

The Act defines an endangered species as any species that is ``in
danger of extinction throughout all or a significant portion of its
range'' and a threatened species as any species ``that is likely to
become endangered throughout all or a significant portion of its range
within the foreseeable future.'' We have carefully assessed the best
scientific and commercial information available regarding the status of
the narrow-headed gartersnake and have determined that this species
meets the definition of a threatened subspecies under the Act based on
its current status and the future threats to the species.
We find that the narrow-headed gartersnake is not currently in
danger of extinction because it remains extant in most of the subbasins
where it historically occurred, and its known threats have not yet
resulted in substantial range reduction or a substantial number of
population extirpations to put the species on the brink of extinction.
Currently, only 5 former populations were found to be likely
extirpated, and 36 populations are believed to remain extant.
Therefore, we determined that the present risk of extinction is not
sufficient to warrant a finding of endangered under the Act.
However, the narrow-headed gartersnake has undergone declines in
its abundance, and we found only 5 of 36 current populations are likely
viable into the foreseeable future, or what we consider to be the next
several decades. We expect the status of the species will decline in
the next several decades mainly as a result of the continuing and
expanding impacts of harmful nonnative species and the increasing
nature of threats associated with human population growth and climate
change. As the effects of these threats escalate on the landscape (as
summarized below), we expect that additional populations will be
extirpated, and that the narrow-headed gartersnake will be in danger of
extinction in the foreseeable future.
In our review of the best available scientific and commercial
information, we found that native fish communities, upon which the
narrow-headed gartersnake relies heavily, have been significantly
degraded by the introduction and proliferation of harmful nonnative
species (Factors C and E). Harmful nonnative species (mainly predatory
fishes, bullfrogs, and crayfish) have been intentionally released or
have naturally moved into nearly every subbasin throughout the range of
the narrow-headed gartersnake. This has resulted in widespread declines
in native fish communities, which are integral to the continued
survival of the narrow-headed gartersnake because they serve as their
primary food source. Harmful nonnative species have indirectly impacted
narrow-headed gartersnakes by predation on their prey base (native
fish) and have directly impacted them through preying on young
gartersnakes (Factor B), which impacts gartersnake populations through
the decline in

[[Page 38743]]

recruitment of young snakes into the reproductive age class. In
combination, these factors have resulted in population declines, range
restrictions within subbasins, and some population extirpations. We
found the threat related to harmful nonnative species to be the most
significant and pervasive of all threats affecting the species.
Additional threats to the habitat of narrow-headed gartersnakes
include water use activities, climate change, and wildfires (Factor A).
Dams, water diversions, flood-control projects, and groundwater pumping
have dewatered entire reaches of historically occupied habitat in some
areas. The rapidly growing human population in the arid southwestern
United States, combined with a drought-limited supply of surface water,
will further increase future needs for water supplies and associated
infrastructure (dams, diversions, and groundwater pumping) that will
also contribute to habitat losses in the next several decades. Losses
of aquatic habitats are also expected due to the impacts of climate
change, which includes increased aridity, lower annual precipitation
totals, lower snow pack levels, higher variability in flows (lower low-
flows and higher high-flows), and enhanced stress on ponderosa pine
communities in the southwestern United States. Wildfires in the arid
southwestern United States have grown more frequent and severe, due in
part to the fire management policies of past decades. High-intensity
wildfires that affect large areas contribute to significant flooding
and sedimentation, resulting in fish kills and the filling-in of
interstitial spaces in river cobble, which the species uses for hunting
fish), as well as important pool habitat. These impacts negatively
affect the fish and amphibian prey base for narrow-headed gartersnakes
for extended periods of time. The frequency and intensity of large
wildfires is likely to increase in the foreseeable future as an
indirect effect of drier and hotter landscape conditions associated
with climate change. The population-level effect of factors that modify
or destroy the physical attributes of gartersnake habitat is amplified
when they act in the presence of harmful nonnative species.
Other factors act in combination to negatively affect the narrow-
headed gartersnake, including road construction, use, and maintenance
(Factor A); adverse human interactions (Factor E); environmental
contaminants (Factor A); and erosion control techniques (Factor A).
These threats occur within the distribution of this gartersnake and
contribute to further population declines or extirpations where
gartersnakes already occur at low population densities due to the
impacts of harmful nonnative species. The existing regulatory
mechanisms currently in place (Factor D) do not target the conservation
of this species or its habitat.
Therefore, on the basis of the best available scientific and
commercial information, we find the narrow-headed gartersnake is likely
to become in danger of extinction throughout all of its range within
the foreseeable future, and we are listing the narrow-headed
gartersnake as a threatened species in accordance with sections 3(20)
and 4(a)(1) of the Act.

Available Conservation Measures

Conservation measures provided to species listed as endangered or
threatened under the Act include recognition, recovery actions,
requirements for Federal protection, and prohibitions against certain
practices. Recognition through listing results in public awareness and
conservation by Federal, State, Tribal, and local agencies, private
organizations, and individuals. The Act encourages cooperation with the
States and requires that recovery actions be carried out for all listed
species. The protection required by Federal agencies and the
prohibitions against certain activities are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Subsection 4(f) of the Act requires the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The recovery planning process involves the
identification of actions that are necessary to halt or reverse the
species' decline by addressing the threats to its survival and
recovery. The goal of this process is to restore listed species to a
point where they are secure, self-sustaining, and functioning
components of their ecosystems.
Recovery planning includes the development of a recovery outline
shortly after a species is listed, preparation of a draft and final
recovery plan, and revisions to the plan as significant new information
becomes available. The recovery outline guides the immediate
implementation of urgent recovery actions and describes the process to
be used to develop a recovery plan. The recovery plan identifies site-
specific management actions that will achieve recovery of the species,
measurable criteria that determine when a species may be downlisted or
delisted, and methods for monitoring recovery progress. Recovery plans
also establish a framework for agencies to coordinate their recovery
efforts and provide estimates of the cost of implementing recovery
tasks. Recovery teams (composed of species experts, Federal and State
agencies, nongovernmental organizations, and stakeholders) are often
established to develop recovery plans. When completed, the recovery
outline, draft recovery plan, and the final recovery plan will be
available on our Web site (http://www.fws.gov/endangered), or from our
Arizona Ecological Services Field Office (see FOR FURTHER INFORMATION
CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribal, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
Following publication of this final listing rule, funding for
recovery actions will be available from a variety of sources, including
Federal budgets, State programs, and cost-share grants for non-Federal
landowners, the academic community, and nongovernmental organizations.
In addition, under section 6 of the Act, the States of Arizona and New
Mexico would be eligible for Federal funds to implement management
actions that promote the protection and recovery of the northern
Mexican and narrow-headed gartersnakes. Information on our grant
programs that are available to aid species recovery can be found at:
http://www.fws.gov/grants.
Please let us know if you are interested in participating in
recovery efforts for these species. Additionally, we invite you to
submit any new information on these species whenever it becomes
available and any information you may have for recovery planning
purposes (see FOR FURTHER INFORMATION CONTACT).
Section 7(a) of the Act requires Federal agencies to evaluate their
actions with respect to any species that is proposed or listed as
endangered or

[[Page 38744]]

threatened and with respect to its critical habitat, if any is
designated. Regulations implementing this interagency cooperation
provision of the Act are codified at 50 CFR part 402. Section 7(a)(4)
of the Act requires Federal agencies to confer with the Service on any
action that is likely to jeopardize the continued existence of a
species proposed for listing or result in destruction or adverse
modification of proposed critical habitat. If a species is listed
subsequently, section 7(a)(2) of the Act requires Federal agencies to
ensure that activities they authorize, fund, or carry out are not
likely to jeopardize the continued existence of the species or destroy
or adversely modify its critical habitat. If a Federal action may
affect a listed species or its critical habitat, the responsible
Federal agency must enter into formal consultation with the Service.
Federal agency actions within the species' habitats that may
require conference or consultation or both as described in the
preceding paragraph include management and any other landscape-altering
activities on Federal lands administered by the Fish and Wildlife
Service, U.S. Bureau of Reclamation, or U.S. Forest Service; issuance
of section 404 Clean Water Act permits by the U.S. Army Corps of
Engineers; construction and management of gas pipeline and power line
rights-of-way by the Federal Energy Regulatory Commission; construction
and maintenance of roads or highways by the Federal Highway
Administration; and other discretionary actions that affect the species
composition of biotic communities where these species or their habitats
occur, such as funding or permitting programs that result in the
continued stocking of nonnative, predatory fish.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to all endangered
wildlife. The prohibitions of section 9(a)(2) of the Act, codified at
50 CFR 17.21 for endangered wildlife, in part, make it illegal for any
person subject to the jurisdiction of the United States to take
(includes harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect; or to attempt any of these), import, export, ship
in interstate commerce in the course of commercial activity, or sell or
offer for sale in interstate or foreign commerce any listed species.
Under the Lacey Act (18 U.S.C. 42-43; 16 U.S.C. 3371-3378), it is also
illegal to possess, sell, deliver, carry, transport, or ship any such
wildlife that has been taken illegally. Certain exceptions apply to
agents of the Service and State conservation agencies. The prohibitions
of section 9(a)(2) of the Act, codified at 50 CFR 17.31 for threatened
wildlife, make it such that all the provisions of 50 CFR 17.21 apply,
except Sec. 17.21(c)(5).
We may issue permits to carry out otherwise prohibited activities
involving endangered and threatened wildlife species under certain
circumstances. Regulations governing permits are codified at 50 CFR
17.22 for endangered species, and at Sec. 17.32 for threatened
species. A permit must be issued for the following purposes: For
scientific purposes, to enhance the propagation or survival of the
species, and for incidental take in connection with otherwise lawful
activities.
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a proposed
listing on proposed and ongoing activities within the range of species
proposed for listing. The following activities could potentially result
in a violation of section 9 of the Act; this list is not comprehensive:
(1) Unauthorized collecting, handling, possessing, selling,
delivering, carrying, or transporting of the species, including import
or export across State lines and international boundaries, except for
properly documented antique specimens of these taxa at least 100 years
old, as defined by section 10(h)(1) of the Act;
(2) The unauthorized introduction of harmful nonnative species that
compete with or prey upon northern Mexican and narrow-headed
gartersnakes or their prey species, such as the stocking of nonnative,
predatory fish, or illegal transport, use, or release of bullfrogs or
crayfish in the States of Arizona and New Mexico;
(3) The unauthorized release of biological control agents that
attack any age class of northern Mexican and narrow-headed gartersnakes
or any life stage of their prey species;
(4) Unauthorized modification of the channel, reduction or
elimination of water flow of any stream or water body, or the complete
removal or significant destruction of riparian vegetation associated
with occupied northern Mexican or narrow-headed gartersnake habitat;
and
(5) Unauthorized discharge of chemicals or fill material into any
waters in which northern Mexican and narrow-headed gartersnakes are
known to occur.
Questions regarding whether specific activities would constitute a
violation of section 9 of the Act should be directed to the Arizona
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).
Requests for copies of the regulations concerning listed animals and
general inquiries regarding prohibitions and permits may be addressed
to the U.S. Fish and Wildlife Service, Endangered Species Permits, P.O.
Box 1306, Albuquerque, New Mexico 87103 (telephone (505) 248-6920,
facsimile (505) 248-6922).

Rule for the Northern Mexican Gartersnake Under Section 4(d) of the Act

The Act does not specify particular prohibitions, or exceptions to
those prohibitions, for threatened species. Instead, under section 4(d)
of the Act, the Secretary of the Interior has the discretion to issue
such regulations as she deems necessary and advisable to provide for
the conservation of such species. The Secretary also has the discretion
to prohibit by regulation with respect to any threatened species, any
act prohibited under section 9(a)(1) of the Act. Exercising this
discretion, the Service developed general prohibitions (50 CFR 17.31)
and exceptions to those prohibitions (50 CFR 17.32) under the Act that
apply to most threatened species. Alternately, for other threatened
species, the Service may develop specific prohibitions and exceptions
that are tailored to the specific conservation needs of the species. In
such cases, some of the prohibitions and authorizations under 50 CFR
17.31 and 17.32 may be appropriate for the species and incorporated
into a rule under section 4(d) of the Act. However, these rules, known
as 4(d) rules, will also include provisions that are tailored to the
specific conservation needs of the threatened species and may be more
or less restrictive than the general provisions at 50 CFR 17.31.

Provisions of the Section 4(d) Rule

Under section 4(d) of the Act, the Secretary may promulgate a
special rule that modifies the standard protections for threatened
species with measures tailored to the conservation of the species that
are determined to be necessary and advisable. Under this 4(d) rule, all
of the prohibitions under 50 CFR 17.31 and 17.32 will apply to the
northern Mexican gartersnake, except as discussed below. The 4(d) rule
will not remove or alter in any way the consultation requirements under
section 7 of the Act.

[[Page 38745]]

The creation, use, and maintenance of stock tanks are important
components of livestock grazing in the southwestern United States. A
stock tank (or livestock tank) is defined as an existing or future
impoundment in an ephemeral drainage or upland site (as opposed to an
active stream channel) constructed primarily as a watering site for
livestock. Well-managed stock tanks can provide important habitats for
northern Mexican gartersnakes and their prey base, especially when the
tank: (1) Remains devoid of harmful nonnative species while supporting
native prey species; (2) provides adequate vegetation cover for
predator aversion and prey base support; and (3) provides reliable
water sources in periods of prolonged drought. However, to create or
maintain these physical attributes of well-managed tanks, management
and maintenance can be necessary, which may have temporary negative
effects to these habitat attributes, but also long-term beneficial
effects to wildlife, including the northern Mexican gartersnake and its
prey. Therefore, the management of stock tanks is an important
consideration for northern Mexican gartersnakes.
The 4(d) rule allows for use of stock tanks by livestock and
construction, continued use, and maintenance of those stock tanks.
Stock tanks provide habitat for northern Mexican gartersnakes, and thus
their presence within the gartersnake's range provides a conservation
benefit to the species. This 4(d) rule allows landowners to construct
new stock tanks and to continue to use and maintain those stock tanks
on non-Federal lands without the need for Federal permitting or
oversight regarding compliance with the Act.
This provision may result in some harm or disturbance of individual
northern Mexican gartersnakes as a result of livestock or human
activities at the stock tanks; however, the level of disturbance is
expected to be minimal and outweighed by the benefit to the species
from the presence of these habitats that are provided by stock tanks.
Given the benefits of well-managed stock tanks, the presence of
well-managed stock tanks are an important component to northern Mexican
gartersnake conservation and recovery. This stock tank provision in the
4(d) rule allows for construction, continued use, and maintenance of
stock tanks on non-Federal lands, and, therefore, because of the
benefits associated with the habitat provided by well-managed stock
tanks, the 4(d) rule is necessary and advisable for the conservation of
the northern Mexican gartersnake.
Nothing in this 4(d) rule changes in any way the recovery planning
provisions of section 4(f) and consultation requirements under section
7 of the Act or the ability of the Service to enter into partnerships
for the management and protection of the northern Mexican gartersnake.
Livestock use and maintenance of stock tanks on Federal lands will be
addressed through the section 7 consultation process; this 4(d) rule
applies only to non-Federal lands.

4(d) Rule Determination

Section 4(d) of the Act states that ``the Secretary shall issue
such regulations as she deems necessary and advisable to provide for
the conservation'' of species listed as a threatened species.
Conservation is defined in the Act to mean ``to use and the use of all
methods and procedures which are necessary to bring any endangered
species or threatened species to the point at which the measures
provided pursuant to (the Act) are no longer necessary.'' Additionally,
section 4(d) states that the Secretary ``may by regulation prohibit
with respect to any threatened species any act prohibited under section
9(a)(1).''
The courts have recognized the extent of the Secretary's discretion
under this standard to develop rules that are appropriate for the
conservation of a species. For example, the Secretary may find that it
is necessary and advisable not to include a taking prohibition, or to
include a limited taking prohibition. See Alsea Valley Alliance v.
Lautenbacher, 2007 U.S. Dist. Lexis 60203 (D. Or. 2007); Washington
Environmental Council v. National Marine Fisheries Service, and 2002
U.S. Dist. Lexis 5432 (W.D. Wash. 2002). In addition, as affirmed in
State of Louisiana v. Verity, 853 F.2d 322 (5th Cir. 1988), the rule
need not address all the threats to the species. As noted by Congress
when the Act was initially enacted, ``once an animal is on the
threatened list, the Secretary has an almost infinite number of options
available to her with regard to the permitted activities for those
species.'' She may, for example, permit taking, but not importation of
such species, or she may choose to forbid both taking and importation
but allow the transportation of such species, as long as the measures
will ``serve to conserve, protect, or restore the species concerned in
accordance with the purposes of the Act'' (H.R. Rep. No. 412, 93rd
Cong., 1st Sess. 1973).
Section 9 prohibitions make it illegal for any person subject to
the jurisdiction of the United States to take (including harass, harm,
pursue, shoot, wound, kill, trap, capture, or collect; or attempt any
of these), import or export, ship in interstate commerce in the course
of commercial activity, or sell or offer for sale in interstate or
foreign commerce any wildlife species listed as an endangered species,
without written authorization. It also is illegal under section 9(a)(1)
of the Act to possess, sell, deliver, carry, transport, or ship any
such wildlife that is taken illegally. Prohibited actions consistent
with section 9 of the Act are outlined for threatened species in 50 CFR
17.31(a) and (b). This 4(d) rule applies all of the prohibitions in 50
CFR 17.31(a) and (b) to the northern Mexican gartersnake, except
activities on non-Federal lands that are incidental to construction,
continued use, and maintenance of stock tanks. Based on the rationale
explained above, the provisions included in this 4(d) rule are expected
to contribute to the conservation of the northern Mexican gartersnake
and are, therefore, necessary and advisable to provide for the
conservation of the northern Mexican gartersnake.

Required Determinations

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

We have determined that environmental assessments and environmental
impact statements, as defined under the authority of NEPA, need not be
prepared in connection with listing a species as an endangered or
threatened species under the Act. We published a notice outlining our
reasons for this determination in the Federal Register on October 25,
1983 (48 FR 49244). As documented in the Service's Endangered Species
Listing Handbook (Service 1994), it is the position of the Service that
rules promulgated under section 4(d) of the Act concurrently with
listing of the species fall under the same rationale as outlined in the
October 25, 1983, determination; thus preparation of an environmental
assessment for the 4(d) rule is not required.

Government-to-Government Relationship With Tribes

In accordance with the President's memorandum of April 29, 1994
(Government-to-Government Relations with Native American Tribal
Governments; 59 FR 22951), Executive Order 13175 (Consultation and
Coordination with Indian Tribal Governments), and the Department of the
Interior's manual at 512 DM 2, we readily acknowledge our
responsibility

[[Page 38746]]

to communicate meaningfully with recognized Federal Tribes on a
government-to-government basis. In accordance with Secretarial Order
3206 of June 5, 1997 (American Indian Tribal Rights, Federal-Tribal
Trust Responsibilities, and the Endangered Species Act), we readily
acknowledge our responsibilities to work directly with tribes in
developing programs for healthy ecosystems, to acknowledge that tribal
lands are not subject to the same controls as Federal public lands, to
remain sensitive to Indian culture, and to make information available
to tribes.
Native American tribes potentially affected by the listing of these
two gartersnakes include the San Carlos Apache Tribe, White Mountain
Apache Tribe, and Yavapai Apache Tribe. On March 12, 2013, we mailed
correspondence to these three tribes to request to meet with each tribe
to discuss our listing recommendations for the gartersnakes. We met
with representatives of the San Carlos Apache Tribe on May 1, 2013, and
no concerns regarding the proposed listings were noted. We held a
government-to-government meeting with the White Mountain Apache Tribe
on September 27, 2013, to discuss the gartersnake listing
recommendations, and we agreed to review their Native Fish Management
Plan for conservation benefit to proposed and listed aquatic vertebrate
species that occur on their lands. We provided comments on that plan
during a conference call discussion on December 16, 2013. The Yavapai
Apache Tribe did not have any comments on the proposed gartersnake
listings.

References Cited

A complete list of references cited in this rulemaking is available
on the Internet at http://www.regulations.gov and upon request from the
Arizona Ecological Services Field Office (see FOR FURTHER INFORMATION
CONTACT).

Authors

The primary authors of this final rule are the staff members of the
Arizona Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.

Regulation Promulgation

Accordingly, we amend part 17, subchapter B of chapter I, title 50
of the Code of Federal Regulations, as follows:

PART 17--[AMENDED]

0
1. The authority citation for part 17 continues to read as follows:

Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245,
unless otherwise noted.

0
2. Amend Sec. 17.11(h) by adding entries for ``Gartersnake, narrow-
headed'' and ``Gartersnake, northern Mexican'' to the List of
Endangered and Threatened Wildlife in alphabetical order under Reptiles
to read as follows:

Sec. 17.11 Endangered and threatened wildlife.

* * * * *
(h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
------------------------------------------------ population where Critical
Historic range endangered or Status When listed habitat Special rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------

* * * * * * *
Reptiles.....................

* * * * * * *
Gartersnake, narrow-headed... Thamnophis U.S.A. (AZ, NM). Entire.......... T............... ............... NA............. NA.
rufipunctatus.
Gartersnake, northern Mexican Thamnophis eques U.S.A. (AZ, NM), Entire.......... T............... ............... NA............. 17.42(g).
megalops. Mexico.

* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------

0
3. Amend Sec. 17.42 by adding a new paragraph (g) to read as follows:

Sec. 17.42 Special rules--reptiles.

* * * * *
(g) Northern Mexican gartersnake (Thamnophis eques megalops). (1)
Prohibitions. Except as noted in paragraph (g)(2) of this section, all
prohibitions and provisions of Sec. Sec. 17.31 and 17.32 apply to the
northern Mexican gartersnake.
(2) Exemptions from prohibitions. Incidental take of the northern
Mexican gartersnake will not be considered a violation of section 9 of
the Act if the take occurs on non-Federal land and is incidental to
activities pertaining to construction, continued use, and maintenance
of stock tanks. A stock tank is an existing or future impoundment in an
ephemeral drainage or upland site constructed primarily as a watering
site for livestock.

Dated: June 9, 2014.
Stephen Guertin,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2014-14615 Filed 7-7-14; 8:45 am]
BILLING CODE 4310-55-P