[Federal Register: April 15, 2010 (Volume 75, Number 72)]
[Proposed Rules]
[Page 19592-19607]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15ap10-19]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2008-0127]
[MO 92210-0-0008-B2]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition to List the Wyoming Pocket Gopher as Endangered or
Threatened with Critical Habitat
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list the Wyoming pocket gopher
(Thomomys clusius) as endangered or threatened and to designate
critical habitat under the Endangered Species Act of 1973, as amended.
After review of all available scientific and commercial information, we
find that listing the Wyoming pocket gopher as either endangered or
threatened is not warranted at this time. We ask the public to continue
to submit to us any new information that becomes available concerning
the status of, or threats to, the Wyoming pocket gopher or its habitat.
DATES: The finding announced in this document was made on April 15,
2010.
ADDRESSES: This finding is available on the Internet at http://
www.regulations.gov at Docket Number FWS-R6-ES-2008-0127. Supporting
documentation we used in preparing this finding is available for public
inspection, by appointment, during normal business hours at the U.S.
Fish and Wildlife Service, Wyoming Ecological Services Field Office,
5353 Yellowstone Road, Cheyenne, WY 82009. Please submit any new
information, materials, comments, or questions concerning this finding
to the above street address.
FOR FURTHER INFORMATION CONTACT: Brian Kelly, Field Supervisor, Wyoming
[[Page 19593]]
Ecological Services Field Office (see ADDRESSES); by telephone at 307-
772-2374; or by facsimile at 307-772-2358. If you use a
telecommunications device for the deaf (TDD), call the Federal
Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (Act) (16 U.S.C. 1531 et seq.) requires that, for any petition
to revise the Federal Lists of Endangered and Threatened Wildlife and
Plants that presents substantial scientific or commercial information
indicating that listing the species may be warranted, we make a finding
within 12 months of the date of the receipt of the petition. In this
12-month finding, we may determine that the petitioned action is: (1)
Not warranted, (2) warranted, or (3) warranted, but the immediate
proposal of a regulation implementing the petitioned action is
precluded by other pending proposals to determine whether species are
endangered or threatened, and expeditious progress is being made to add
or remove qualified species from the Federal Lists of Endangered and
Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires
that we treat a petition for which the requested action is found to be
warranted but precluded as though resubmitted on the date of such
finding, that is, requiring a subsequent finding to be made within 12
months. We must publish these 12-month findings in the Federal
Register.
Previous Federal Actions
On August 9, 2007, we received a petition, dated August 7, 2007,
from the Biodiversity Conservation Alliance and Center for Native
Ecosystems requesting that we list the Wyoming pocket gopher (Thomomys
clusius) within its known historic range, as threatened or endangered
under the Act. Additionally, the petition requested that we designate
critical habitat concurrent with listing. We acknowledged receipt of
the petition in a letter dated September 6, 2007. In that letter, we
advised the petitioners that we could not address their petition at
that time because responding to existing court orders and settlement
agreements for other listing actions required nearly all of our listing
funding. We also concluded in that September 6, 2007, letter that
emergency listing of the Wyoming pocket gopher was not warranted.
On July 11, 2008, we informed the petitioners that, due to progress
on addressing other priority listing actions, funding had become
available to allow us to address the petition in fiscal year 2008. On
November 4, 2008, the petitioners filed a complaint with the U.S.
District Court for the District of Colorado against us for failing to
complete the 90-day finding (Center for Native Ecosystems and
Biodiversity Conservation Alliance v. U.S. Fish and Wildlife Service
and Kempthorne (1:08-cv-02394-JLK)).
On February 10, 2009, we published our finding that the petition to
list the Wyoming pocket gopher presented substantial scientific or
commercial information indicating that listing the species may be
warranted (74 FR 6558). On March 20, 2009, the petitioners provided a
notice of intent to sue on additional grounds for failure to complete
the 12-month finding within 12 months of the petition. In a June 12,
2009, stipulated settlement, the Service agreed to complete the 12-
month finding by April 10, 2010, which would allow us to include 2009
Wyoming pocket gopher survey data in our analysis. This notice
constitutes our 12-month finding on the August 7, 2007, petition to
list the Wyoming pocket gopher as endangered or threatened.
Species Information
Life History
Pocket gophers are powerfully built mammals, characterized by a
heavily muscled head without a noticeable neck, strong front limbs with
long nails used for digging, small ears, small eyes, and fur-lined
cheek pouches used to carry food (Verts and Carraway 1999, p. 3). They
are highly fossorial (adapted to burrowing or digging), living,
foraging, and reproducing in burrow systems and underground tunnels
that provide protection from predators and from extreme environmental
conditions (Clark and Stromberg 1987, p. 121).
Populations of pocket gophers generally tend to be small and
patchily distributed across landscapes where they occur (Kennerly 1959,
p. 251; Stinson 2005, p. 21). This distribution is thought to be
primarily determined by the availability of soils appropriate for
digging and foraging (Kennerly 1959, p. 249; Verts and Carraway 1999,
p. 5). Specialization to local ecological conditions has resulted in a
high degree of morphological variation across the range of each species
(Patton and Brylski 1987, p. 493). For example, pocket gopher coat
color is highly variable, strongly correlated with soil color, and
thought to be an adaptive response to predation (Ingles 1950, p. 357;
Wlasiuk and Nachman 2007, p. 567). Differences in abundance and
nutritional content of forage can produce extreme variation in body
size of individual pocket gophers and density of pocket gopher
populations (Patton and Brylski 1987, p. 504).
Little is known about the Wyoming pocket gopher; assumptions about
its distribution, ecology, and status are based on a few museum
records, reports from more than 30 years ago, and research conducted in
2008 and 2009. This lack of knowledge has led to the recent efforts to
obtain information on its distribution, status, and habitat use
(Keinath and Griscom 2008, p. 1; Griscom et al. 2010, p. 3). Where
specific life-history information is lacking, and where appropriate, we
have provided information from other pocket gopher species, mainly in
the Thomomys genus.
The Wyoming pocket gopher is differentiated from other pocket
gophers in its geographical range by being smaller and paler, with a
yellow cast to the coat, especially in younger animals. The dorsal coat
is uniform in color, and the margins of the ears are fringed with
whitish hairs (Thaeler and Hinesley 1979, p. 483; Clark and Stromberg
1987, p. 123; Keinath and Beauvais 2006, p. 8; Keinath and Griscom
2008, p. 2). This species does not display sexual dimorphism
(differences in form between the sexes) (Clark and Stromberg 1987, p.
123; Keinath and Beauvais 2006, p. 8). Adult Wyoming pocket gophers
typically have a body length of 112-134 millimeters (mm) (4.41-5.28
inches (in)), hind foot length of 20-22 mm (0.79-0.87 in), and a weight
of 44-72 grams (g) (1.54-2.54 ounces (oz)) (Thaeler and Hinesley 1979,
pp. 483-484; Clark and Stromberg 1987, p. 123). The measurements of
specimens captured in 2008 and 2009 included body lengths of 86-128 mm
(3.38-5.04 in), hind foot lengths of 15-23 mm (0.59-0.91 in), and
weights of 43-66 g (1.52-2.33 oz) (Griscom et al. 2010, p. 23). These
somewhat smaller measurements for 2008-2009 data can be partly
explained by late summer captures that included juveniles, whereas
older studies relied on captures prior to June 15 that would have
included only adults (Griscom 2010a, pers. comm.).
The Wyoming pocket gopher occurs entirely within the range of the
northern pocket gopher (Thomomys talpoides), but the two species likely
occupy different habitats locally (Thaeler and Hinesley 1979, p. 486;
Keinath and Beauvais 2006, p. 8; Griscom et al. 2010, p. 15).
Approximately 50 percent of the known range of the species occurs on
Bureau of Land Management (BLM) lands (Service 2009a, p. 1). A Wyoming
Natural Diversity Database (WYNDD) predictive distribution model for
the
[[Page 19594]]
Wyoming pocket gopher developed in January 2010 shows the species could
occur in Sweetwater, Carbon, and Fremont Counties in Wyoming (Griscom
et al. 2010, p. 32). The predicted range abuts Colorado's northern
border, but Colorado was not included in the distribution analysis
(Griscom et al. 2010, p. 32). Additional specimens are considered
unlikely to be found south of current distribution points (Griscom et
al. 2010, p. 12). To date, Wyoming pocket gophers have been located
only in Sweetwater and Carbon Counties, which is consistent with
historical records that show this area to be the extent of the species'
range. Although the full historic range of the species has not been
defined, we consider the capture points in Sweetwater and Carbon
Counties presented by Thaeler and Hinesley (1979, pp. 482, 486-487) to
present an approximation of historic range. This historic range
includes the type specimen collected in 1857, two specimens collected
in 1949 and 1951, and several specimens collected in the 1960s and
1970s (Thaeler and Hinesley 1979, p. 487). Very little information
exists regarding the actual population size of the Wyoming pocket
gopher (Keinath and Beauvais 2006, p. 21). The only population estimate
we found was 10,000 (NatureServe 2009, unpaginated). However, we are
unable to determine the basis for this estimate and thus have no way to
determine its scientific validity.
Vegetation composition of a site may be more important in
determining habitat for the Wyoming pocket gopher than soils or
topography (Keinath and Griscom 2008, p. 2). The Wyoming pocket gopher
occurs primarily in small ``islands'' of low vegetation within a
sagebrush matrix. This matrix typically includes Artemesia tridentada
wyomingensis (Wyoming big sagebrush), Chrysothamnus spp. (rabbitbrush),
and other low shrubs, cushion plants, grasses, and forbs (Keinath and
Griscom 2009, p. 1). In comparison to unoccupied control sites and
northern pocket gopher capture sites, the Wyoming pocket gopher appears
to prefer areas within this matrix with less perennial grass cover,
less Artemesia tridentata (Big sagebrush), more Krascheninnikovia
lanata (winterfat), more Atriplex gardneri (Gardner saltbush), more
bare soil, less litter, and fewer surface rocks (Griscom et al. 2010,
p. 15). Difference in habitat use would be expected, given that
phenotype (observable physical characteristics) has been shown to
correlate with habitat for pocket gophers (Ingles 1950, p. 357; Wlasiuk
and Nachman 2007, p. 567).
Previously, the Wyoming pocket gopher was believed to exclusively
occupy well-drained, gravelly ridges instead of the valley bottoms and
riparian areas with deeper soils preferred by the northern pocket
gopher (Thaeler and Hinesley 1979, p. 486). However, recent research
showed Wyoming pocket gophers occupy sites with more varied topography
(Keinath and Griscom 2008, p. 2). Compared to northern pocket gophers,
Wyoming pocket gophers appear to prefer areas of lesser slopes (Griscom
et al. 2010, p. 15). Wyoming pocket gophers appear to use a variety of
soil types that can be more compacted than those used by northern
pocket gophers (Griscom et al. 2010, p. 15). These soils often have a
substantial gravel component, usually contain little clay (Keinath and
Griscom 2008, p. 2), and tend to be more alkaline than the soils that
northern pocket gophers prefer (Griscom 2009a, pers. comm.). In
general, pocket gophers in the Thomomys genus are more specialized for
tooth digging rather than claw digging, which allows for exploitation
of a broader range of soil types (Lessa and Thaeler 1989, p. 696).
Based on the characterization of the Wyoming pocket gopher's size and
habitat, it appears to fit the island model of isolation displayed by
other species of pocket gophers specifically adapted to the soils of an
area (Miller 1964, pp. 259-260). The limited distribution of the
Wyoming pocket gopher relative to other species of pocket gopher may be
due to its specialized habitat requirements (Keinath and Beauvais 2006,
pp. 12-15).
Pocket gophers construct extensive burrow systems. These systems
consist of a main tunnel with side branches of shallow feeding tunnels
(tunnels dug to forage on plant material). Additional feeding tunnels
can be constructed when plant production is poor (Davis 1938, p. 338;
Reichman et al. 1982, p. 691). The main tunnel also connects to a
smaller system of chambers that serve as nest sites, food caches, and
latrines (Miller 1964, p. 257; Keinath and Beauvais 2006, p. 16).
Depths of the burrows vary from 6 to 12 inches below the ground
surface. All aboveground entrances are plugged with soil (Clark and
Stromberg 1987, p. 121). Burrow widths of the Wyoming pocket gopher are
significantly smaller than those of the northern pocket gopher, likely
reflecting their smaller body size (Griscom et al. 2010, p. 15). The
extent of burrow systems can vary with the size of the individual, soil
type, and plant production. The extensive tunneling and feeding
activity of pocket gophers can have strong effects on soil formation,
hydrology, nutrient flows, plant diversity, and competitive
interactions of plants (Tilman 1983, pp. 290-292; Huntly and Inouye
1988, entire; Reichman and Seabloom 2002, entire; Sherrod et al. 2005,
pp. 586-587; Kyle et al. 2008, p. 377). The effects of pocket gopher
burrowing on physical and chemical soil properties vary based on the
nature of the soil (Kerley et al. 2004, pp. 164-165).
The diet of pocket gophers consists of roots, stems, and leaves of
forbs, with some consumption of grasses and shrubs (Aldous 1951, pp.
85-86; Ward and Keith 1962, p. 747). The average consumption of forbs
by pocket gophers in west-central Colorado, as measured by stomach
content, was highest in July and August at 96 percent, decreasing to 73
percent in October (Ward and Keith 1962, p. 747). Consumption of shrubs
and roots of all types increased in late September and October, and
consumption of grasses increased in June, September, and October (Ward
and Keith 1962, p. 747). Pocket gophers in the Thomomys genus
throughout the western United States generally prefer forb shoots
during the growing season, and grass shoots, corms, and roots during
periods of plant dormancy (Hunt 1992, pp. 47-48). Other species of the
Thomomys genus (e.g., northern pocket gopher, Botta's (valley) pocket
gopher (T. bottae), Townsend's pocket gopher (T. townsendii), Mazama
(western) pocket gopher (T. mazama), and Camas pocket gopher (T.
bulbivorus)) are not strict herbivores, in that they also seasonally
consume the fungi associated with plant roots (i.e., are mycophagous)
(Maser et al. 1978, p. 805; Taylor et al. 2009, p. 367). Pocket gophers
may cut their food into small pieces and carry it in their cheek
pouches back to the main burrow where it is consumed, stored for
winter, used for nest building, or taken into tunnels and later pushed
to the surface (Aldous 1951, p. 84; Verts and Carraway 1999, p. 6).
Pocket gophers remain active all winter (Clark and Stromberg 1987, p.
121).
Based on the life histories of other pocket gophers, Wyoming pocket
gophers presumably reproduce the calendar year following birth, have
one litter with 4 to 6 young per year, and usually do not live more
than two breeding seasons (Keinath and Beauvais 2006, p. 18). However,
one northern pocket gopher is known to have survived for about 4 years
(Hansen 1962, p. 153). Some species of pocket gophers have more than
one litter per year in southern climates with longer breeding seasons
(Miller 1946, pp. 335-336). Hansen (1960, p. 332) found no
[[Page 19595]]
evidence of more than one annual litter per female in the Rocky
Mountain region.
Pocket gophers are solitary animals and are typically found
together only during the breeding season, or when females have young.
Variation in levels of tolerance between males and females ranges from
being together only during mating to raising young of the year together
(Hansen and Miller 1959, pp. 581-582). Pocket gophers are usually
polygynous (Reichman et al. 1982, p. 693). However, some evidence of
serial monogamy has been found in Botta's pocket gopher in Arizona
(Reichman et al. 1982, p. 693). The sex ratio for Botta's pocket gopher
was one male per one female; however, the effective sex ratio was one
male per two females as some small males did not reproduce (Reichman et
al. 1982, p. 693). Populations of Botta's pocket gopher in California
showed a much more skewed sex ratio, ranging from 1.4 to 4.67 females
per male (Patton and Feder 1981, p. 917). We do not have specific
information regarding the Wyoming pocket gopher mating system or sex
ratio.
Outside of the breeding season, pocket gophers are highly
territorial, and males and females have exclusive territories.
Generally, pocket gophers avoid each other (Reichman et al. 1982, p.
693). The infrequent interactions that occur are mostly agonistic,
occasionally escalating to open combat and even death (Zinnel and
Tester 1994, p. 96). This aggression appears to have evolved as a means
to ensure adequate individual food supplies, but could also be related
to reproductive behaviors like mate guarding (Zinnel and Tester 1994,
pp. 99-100). Pocket gopher population density is likely to be primarily
regulated through intraspecific aggression; the number of animals an
area can hold appears to be determined by combative interactions
(Zinnel and Tester 1994, p. 100).
Dispersal strategies of the Wyoming pocket gopher are unknown, but
may be similar to other pocket gopher species. Although dispersal was
common, 63 percent of individual Botta's pocket gophers set up their
territory within 40 meters (m) (131.23 feet (ft)) of their natal home
(Daly and Patton 1990, p. 1291). Average dispersal lengths for Botta's
pocket gopher are estimated at 100-500 m (328.08-1,640.42 ft) per year
(Hafner et al. 1998, p. 281). Individual Botta's pocket gophers that
disperse are typically young, pre-reproductive, and more likely to be
female (Daly and Patton 1990, p. 1287). Pre-reproductive juvenile
females begin dispersing as early as the summer following their birth,
while males typically delay dispersal for up to one year after birth
(Daly and Patton 1990, p. 1287). Spring dispersal is common in
reproductive adults of both sexes. Fifty percent of plains pocket
gopher (Geomys bursarius) female adults relocate after raising a
litter, leaving the site in possession of female young (Zinnel and
Tester 1994, p. 99). Once pocket gophers establish territories and
burrows, they may shift to other areas based on environmental
conditions or interactions with other pocket gophers, but they
generally do not move far from original territories (Miller 1964, p.
262; Reichman et al. 1982, pp. 687-688; Daly and Patton 1990, p. 1286).
Taxonomy
The Wyoming pocket gopher (Thomomys clusius) is a member of the
Geomyidae (pocket gopher) family. Including the Wyoming pocket gopher,
nine species are currently assigned to the genus Thomomys. The type
specimen for Wyoming pocket gopher was collected in 1857 by Dr. W.A.
Hammond near Rawlins, Wyoming, but was not described and given the name
Thomomys clusius until 18 years later (Coues 1875, p. 138). The
designation of the Wyoming pocket gopher within Thomomys has changed
over time, with the name clusius being applied at both the species and
subspecies level to various pocket gopher specimens collected in
southern Wyoming (Keinath and Beauvais 2006, p. 11).
Thaeler and Hinesley (1979, entire) clarified the Wyoming pocket
gopher taxonomy with karyotype (i.e., a count of the number of diploid
chromosomes) and morphological analyses of pocket gopher specimens
collected in Wyoming. Members of the pocket gopher genus Thomomys are
the most karyotypically and morphologically diverse group of mammals
known (Patton 1972, p. 574; Patton and Brylski 1987, p. 493). The
Wyoming pocket gopher has a unique karyotype of 2n = 46, a yellowish
coat, and a generally small size, which support the validity of Wyoming
pocket gopher as a distinct species within Thomomys (Thaeler and
Hinseley 1979, p. 483). These traits differed significantly from the
northern pocket gopher, which occurs across the range of the Wyoming
pocket gopher. Although northern pocket gophers are generally darker
and larger, they share morphological similarities with Wyoming pocket
gophers that had led to some misidentification of specimens in earlier
publications (e.g., Bailey 1915 and Long 1965, cited in Keinath and
Beauvais 2006, p. 11). Thus, karyotype analysis was previously thought
necessary for positive identification. Northern pocket gophers differ
from Wyoming pocket gophers in that they have a karyotype of 2n = 48 or
56, depending on the subspecies (Thaeler and Hinesley 1979, p. 483).
However, based on the amplified fragment length polymorphism (AFLP)
analysis completed on tail clippings during the 2008 field season,
field assessment of phenotype was shown to be a reasonably reliable
method for discerning the two species from each other (Hayden-Wing
Associates 2008, p. 3; Beauvais 2009, p. 1; McDonald 2009a, pers.
comm.). AFLP testing showed strong genetic signals that clearly
differentiate the Wyoming pocket gopher from other species of pocket
gophers (Beauvais 2009, p. 1; McDonald 2009a, pers. comm.). This recent
genetic analysis has confirmed definitively what taxonomists had
determined historically: the Wyoming pocket gopher is a unique species
representing a monophyletic clade (i.e., descended from one common
ancestor) (McDonald 2009a, pers. comm.).
Summary of Information Pertaining to the Five Factors
Section 4 of the Act, and its implementing regulations at 50 CFR
424, set forth the procedures for adding species to, removing species
from, or reclassifying species on the Federal Lists of Endangered and
Threatened Wildlife and Plants. Under section 4(a)(1) of the Act, a
species may be determined to be endangered or threatened based on any
of the following 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. Under section 4(b)(1)(A), this
determination should be made on the basis of the best scientific and
commercial data available and after conducting a status review and
taking into consideration State conservation efforts. In making our 12-
month finding on a petition to list the Wyoming pocket gopher, we
considered and evaluated the best available scientific and commercial
information. Information pertaining to the status and threats to the
Wyoming pocket gopher in relation to the five factors provided in
section 4(a)(1) of the Act is discussed below.
[[Page 19596]]
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Wyoming pocket gopher habitat is exposed to a number of influences
that may affect the species, including energy exploration and
development, road construction and use, climate change and drought,
introduction of nonnative species, grazing, and urbanization. However,
no studies have been conducted to determine the species' response to
these influences, or to the potential changes in habitat that may
result. Where information specific to the Wyoming pocket gopher is
lacking, we have utilized information from other pocket gopher species,
mainly in the Thomomys genus.
Literature describes both positive and negative effects to other
species of pocket gophers resulting from various types of disturbance.
Many pocket gopher species exhibit a positive response of increased
rates of mound-building activities when vegetation has been disturbed
(Mielke 1977, p. 175). Three species (Botta's pocket gopher, plains
pocket gopher, and yellow-faced pocket gopher (Cratogeomys castanops))
are more common in disturbed areas, such as roadways and floodplains,
in New Mexico (Best 1973, p. 1314). Similarly, pocket gopher (Thomomys
spp.) burrows were frequently observed along roadways in Nevada, but
not the adjacent creosote habitats, suggesting they were using areas
where the habitat would have been unsuitable without the disturbance
(Garland and Bradley 1984, p. 54). In contrast, plains pocket gophers
and yellow-faced pocket gophers in southwestern Kansas are not present
within areas of intensive agricultural operations involving annual
plowing or disking (Hoffman et al. 2007, p. 300). Intensive residential
and commercial development has reduced patch sizes of Mazama pocket
gopher habitat in western Washington such that the species no longer
occurs in many areas (Service 2009b, pp. 7-8; Flotlin 2010, pers.
comm.). The response to disturbance may be dependent on the species, as
the plains pocket gopher is more common in disturbed areas, such as
roadsides and cultivated fields, while the yellow-faced pocket gopher
is more common in native shortgrass prairie in southeastern Colorado
(Moulton et al. 1983, p. 58).
In 2008 and 2009, WYNDD, with the assistance of several other
groups, trapped Wyoming pocket gophers, northern pocket gophers, and
Idaho pocket gophers (T. idahoensis) to better understand the species'
range and distribution, habitat requirements and preferences, and the
genetic and morphological differences between species (WYNDD 2009, p.
2; Hayden-Wing Associates 2008, p. 1; Keinath and Griscom 2008, p. 1;
Griscom et al. 2010, pp. 5-7). This effort resulted in the successful
trapping of 31 confirmed Wyoming pocket gophers distributed across the
species' currently known range (Griscom et al. 2010, p. 5; Griscom
2010b, pers. comm.). Prior to 2008, a total of 16 confirmed Wyoming
pocket gophers had been captured, and all of these confirmed specimens
were collected by Charles Thaeler approximately 40 years ago (Griscom
2009b, pers. comm). This information provided both historic and recent
locations for our use in creating a general assessment of Wyoming
pocket gopher presence to ascertain if the known locations of the
species have changed over time. Based on the limited number of
collection sites, the species appears to be currently distributed
throughout its known range in a pattern that approximates historic
distribution (Figure 1). Therefore, we find no evidence that
curtailment of the species' range is occurring.
[[Page 19597]]
[GRAPHIC] [TIFF OMITTED] TP15AP10.000
Figure 1: Historic and current capture locations of the Wyoming
pocket gopher (Data compiled from Service, Bureau of Land Management,
WYNDD, U.S. Geological Survey, U.S. Census Bureau, ESRI).
Although there is no evidence of curtailment of the species' range,
habitat of the Wyoming pocket gopher is exposed to various influences
that may affect the species, including energy exploration and
development, road construction and use, introduction of nonnative
species, climate change, drought, grazing, and urbanization. These
variables that may affect the species' habitat are discussed below.
Energy Exploration and Development
The primary forms of existing and planned energy development in the
range of the Wyoming pocket gopher are oil, gas, and wind. Based on
existing
[[Page 19598]]
National Environmental Policy Act (NEPA) (42 U.S.C. 4321 et seq.)
documents for major oil and gas developments, estimates of project life
for major oil and gas developments within the Wyoming pocket gopher's
range are between 10-50 years (Service 2010a, p. 3). Some non-renewable
energy development is already occurring within the species' known
occupied range. Renewable energy development is estimated to reach
maximum development by 2030 (U.S. Department of Energy 2008, p. 10),
and several developments are being considered within the species'
range. Based on this information, we estimate the foreseeable future of
energy development at a minimum of 10 years, but anticipate that energy
development will be present for up to 50 years.
WYNDD is analyzing potential threats to Wyoming's 152 species of
greatest conservation need related to energy development in its
Assessment of Wildlife Vulnerability to Energy Development (AWVED).
Preliminary conclusions from the AWVED analysis indicate that the
Wyoming pocket gopher is Wyoming's species with the highest potential
risk for energy-related effects based on its proximity to existing
wells, the proportion of lands leased for oil and gas within its range,
and the density of wells within that range (Keinath 2009, pp. 12-13).
This potential risk is based on exposure to energy development across
the species' range and is not based on any known effects to the species
from energy development activities. Our February 10, 2009, 90-day
finding (74 FR 6558) acknowledged that the likelihood of oil and gas
development throughout the species' range is high based on the energy
development potential and existing leases that cover much of the range.
Approximately 4,000 actively producing oil and gas wells are within the
range of the species (Service 2010b, p. 3), and an additional 10,000
oil and gas wells have been proposed in that area (Service 2010a, p.
1). In this finding, rather than what was done in our previous 90-day
finding on the petition, we are determining whether the best available
information indicates that the species meets the definition of a
threatened or endangered species and therefore warrants listing under
the Act, which is a more in-depth analysis than the one conducted for
the 90-day finding.
Several different types of oil and gas exploration and development
activities occur within the range of the Wyoming pocket gopher. Oil and
gas geophysical exploration is conducted to generate a subsurface image
of fluid minerals and usually involves either drilling holes and
detonating explosives or using a vibrating pad that is driven across an
area using heavy vehicles. The extent of impacts from either
exploration method on pocket gophers is unknown. The vibrations and
potential soil impacts would, at a minimum, temporarily alter habitat
and may result in collapse of burrows. Pocket gophers in the immediate
vicinity of operations would likely notice the activity, but the type
of response is unknown. Pocket gopher communication likely occurs
through seismic signals (Mason and Narins 2001, p. 1177), and frequent
vibrations could disrupt signals used to attract mates, warn of
intruders, or avoid predators. However, we have no information to
support that energy exploration negatively impacts the species.
Oil and gas development involves staging a drilling rig and setting
up additional equipment that is used during production. Generally,
developers build roads to access each site and clear and level well
pads. These soil-disturbing activities would affect the habitat that
lies within and adjacent to the footprint of well pads and roads. Any
soil that is moved could have a direct impact on pocket gophers that
are present. Once a rig is in place, the drilling process creates
vibrations that could affect habitat and any pocket gophers in the
area. Once a well has been drilled and is producing, energy companies
make regular trips to well pads to monitor production, conduct
maintenance, or collect extracted resources. These regular trips may
disturb, either directly or through the resulting noise, pocket gophers
that are present at or near well pads and roads. In the past, the
Wyoming pocket gopher has been considered potentially vulnerable to
disturbance because the reasons for the species' limited distribution
had not yet been explained (Keinath and Beauvais 2006, p. 21). However,
as described above, certain types of disturbance can elicit a positive
population response in some pocket gopher species.
Energy producers often try to maintain a clear work area by using
herbicides on well pads and along roads. Herbicide use and the direct
impacts of development would reduce the availability and quality of
vegetation, creating negative effects to Wyoming pocket gopher habitat
(Keith et al. 1959, pp. 142-144). In general, broadcast herbicide
application is assumed to be minimal in southern Wyoming (Keinath and
Beauvais 2006, p. 22). We do not have information on use of herbicides
for oil and gas development, and we are unaware of monitoring for
resulting vegetative shifts. Therefore, we are unable to assess how
changes in the vegetation due to herbicide use may affect the Wyoming
pocket gopher. The BLM does not use pesticides or rodenticides in
Wyoming to protect reclamation areas (Abbott 2009a, pers. comm.), so we
do not anticipate direct mortality from these substances in reclamation
areas. Introduction and spread of nonnative plants may result from
energy development activities, and the potential threat of nonnative
vegetation to the Wyoming pocket gopher is discussed separately below.
We used information from Wyoming pocket gopher trapping and from
known oil and gas development to assess the extent to which energy
development may be affecting the species. By overlaying producing wells
on a map with species capture sites, we found that the locations of
capture sites in relation to new and existing development does not
appear to reflect a pattern of either species avoidance of, or
preference for, producing oil and gas wells. Some capture sites are as
near as 95 m (312 ft) to a producing well site (Service 2010b, p. 2),
while others are in areas that have no oil or gas wells. We recognize
that this simple geospatial assessment has limitations in determining
what effects oil and gas development has on the species. We also
recognize dispersal is likely already difficult across portions of the
range that do not currently have pocket gophers, and recolonization
following local extirpation would be unlikely (Keinath et al. 2008, p.
7).
The amount of surface disturbance provides another approach to
consider the impacts of natural gas development. The two largest
natural gas developments not yet fully built in the Wyoming pocket
gopher range are Atlantic Rim and Continental Divide-Creston (Service
2010a, p. 1). The scoping notice for the Continental-Divide Creston
development states disturbances during initial development will be
approximately 47,060 acres (ac) (19,045 hectares (ha)) of 1.1 million
ac (445,154 ha), or 4.28 percent of the project area (BLM 2006a, p. 4).
The impacted area will be reduced to 1.67 percent through interim
reclamation (BLM 2006a, p. 4). As this proposal includes areas of
infill, the amount of disturbance described in the scoping notice does
not include existing development (BLM 2006a, p. 1). The proposed well
density includes 8 wells per square mile, with a possibility of up to
16 wells per square mile in certain areas (BLM 2006a, p. 1). The Record
of Decision for the Atlantic Rim development allows a total surface
[[Page 19599]]
disturbance of 2.8 percent of the project area at a given time, with
well spacing of 8 wells per square mile (BLM 2007, p. 10). For
comparison, the existing Continental Divide/Wamsutter II gas
development has been mostly developed, with 22,400 ac (9,065 ha) of
surface disturbance across 1,061,200 ac (429,452 ha) (2.11 percent of
the project area) and well densities of 1 to 8 wells per square mile
(BLM 2000, section 2.0). All of these surface disturbance percentages
are small. Although we do not know how the Wyoming pocket gopher is
likely to respond to any proposed increases in well numbers, the level
of development indicates that large interstitial spaces will continue
to be available for Wyoming pocket gopher use. We know from our
analysis that the Wyoming pocket gopher does occur near developed areas
(Service 2010b, p. 2).
The BLM administers approximately half of the lands within the
Wyoming pocket gopher range (Service 2009a, p. 1). Throughout the
range, the BLM has leased 41.23 percent of the Wyoming pocket gopher
range for oil and gas development, and 11.23 percent of the range on
BLM lands has producing oil and gas leases (Service 2010c, p. 2). We
are unable to determine whether development will occur on all leases.
Given limited knowledge of pocket gopher response to oil and gas
development, and both the positive and negative observed impacts of
disturbance to other species of pocket gophers, we do not consider
producing wells at current or projected levels to be a threat to the
Wyoming pocket gopher.
Although little wind development has occurred within the range of
the species, projections for future wind energy are significant. One
major proposal, the Chokecherry and Sierra Madre Wind Energy Project,
includes 1,000 wind turbines across 98,500 ac (39.66 ha) within the
range of the Wyoming pocket gopher (AECOM 2009, p. 1). Wind development
may cause effects to habitat that are similar to oil and gas
development. Wind development also results in a network of pads
connected by roads. Soils are disturbed during development, and
frequent maintenance trips are necessary. The Wyoming pocket gopher's
response to wind development within its habitat is not known. For the
Botta's pocket gopher, researchers mapping prey base to better
understand raptor mortalities at a wind farm in California observed
that pocket gophers were clustered near the wind turbines (Thelander et
al. 2003, p. 23). They attributed this to the pocket gophers'
attraction to the vertical and lateral edges formed by access roads and
the area around wind towers (Thelander et al. 2003, p. 24). We
anticipate that the response of the Wyoming pocket gopher may be
similar, but we lack species-specific information. Therefore, the best
available information does not indicate whether current or future wind
development will have positive or negative effects on the Wyoming
pocket gopher.
Summary of Energy Exploration and Development
Little information exists to indicate whether the Wyoming pocket
gopher will be affected by an increased density of wells or by an
expansion of oil, gas, and wind development into currently undeveloped
areas. The response to disturbance in pocket gophers appears to be
species-specific. For example, in southeastern Colorado, the plains
pocket gopher is more common in disturbed areas, but the yellow-faced
pocket gopher is more common in native versus disturbed habitats
(Moulton et al. 1983, p. 58). Based on our current understanding of the
Wyoming pocket gopher, energy development, at levels that we can detect
or anticipate, is as likely to benefit Wyoming pocket gophers as it is
to harm them.
We have no information that additional energy development activity
will fragment habitat in a way that will significantly limit dispersal,
movement, or genetic interchange. Using the best available information,
we conclude that these habitat alterations do not constitute a threat
to the Wyoming pocket gopher now, or in the foreseeable future.
Road Construction and Use
Roads are built to create access for oil, gas, and wind
developments, as well as for other activities that occur on the
landscape, including recreation, grazing, and land management. Much of
the recent expansion of road networks in Wyoming pocket gopher habitat
is related to energy development, but some areas have also likely
experienced an increase in access by recreational vehicles. Expansion
of road networks may fragment the species' habitat, create barriers to
movement of the species, isolate individual populations, and increase
opportunities for invasive species (Keinath and Beauvais 2006, pp. 22-
23). Roads may increase direct mortality from vehicles, but this source
of mortality is not always significant to populations (Garland and
Bradley 1984, p. 52). Roads also may improve habitat for pocket gophers
in some ways by providing looser soil and increasing vegetation in
rights-of-way from precipitation run-off. As described above, roads can
have a positive effect on other pocket gopher species (Best 1973, p.
1314; Moulton et al. 1983, p. 58; Garland and Bradley 1984, p. 54). The
effects of roads on Wyoming pocket gopher populations are not known;
however, we have limited anecdotal observations of individual gopher
occupancy near roads. In 2009, one Wyoming pocket gopher specimen was
captured 7 m (23 ft) from a graded dirt road, and northern pocket
gophers were captured as close as 2 m (6.5 ft) to a graded dirt road
(Griscom 2009b, pers. comm.). Small mammals may avoid roads due to
noise and other factors, but roads may also provide additional habitat
or movement corridors (Garland and Bradley 1984, entire; U.S.
Department of Transportation 2009, unpaginated). Northern pocket
gophers have been observed digging tunnels underneath a right-of-way
road (Richens 1966, p. 532).
Depending upon the size of the road and the associated degree of
soil compaction, a road may impact the dispersal of Wyoming pocket
gophers. For example, distribution of the Shelton pocket gopher (T.
mazama couchi) was impacted by soil compaction around an airport
runway, and no pocket gopher activity was observed in graded areas that
appeared to be highly compacted (GeoEngineers 2003, p. 15). The Wyoming
pocket gopher apparently can use more compacted soils than the northern
pocket gopher (Griscom et al. 2010, p. 15), but we are unsure what
amount of soil compaction would begin to limit habitat use by the
Wyoming pocket gopher.
Many roads in the range of the Wyoming pocket gopher have been on
the landscape for decades or for more than a century, while others have
been developed within the past few years. Evidence suggests some
historic wagon trails (a type of road) have lasted for well over 100
years (BLM 2009, unpaginated), even when use of the road is
discontinued. Other roads are reclaimed and do not have such a lasting
effect. We anticipate that the existing roads within the range of the
Wyoming pocket gopher will persist for at least 10 to 50 years in
support of energy development activities. Additional roads may also be
constructed to support that development, while others are reclaimed
when no longer necessary. We anticipate that county roads providing
access to livestock management facilities, homes, and recreational
opportunities will persist indefinitely.
[[Page 19600]]
We conclude the effects of roads on the Wyoming pocket gopher may
be positive and negative. Although we remain concerned about the
potential impacts of roads, the best available information does not
indicate that road construction and use poses a threat to the Wyoming
pocket gopher now, or in the foreseeable future.
Nonnative Species
The introduction of nonnative species may affect the Wyoming pocket
gopher, but the degree of impact from these species is not clear. A
review of Wyoming pocket gopher information resulted in no information
indicating a likelihood that nonnative vegetation alters or restricts
pocket gopher populations; nonnative species were viewed as a potential
threat, but not a current threat (Keinath and Beauvais 2006, p. 23). We
do not fully understand the extent to which nonnative species will
spread throughout the species' range into the future. Nonnative
vegetation is considered a threat to the Mazama pocket gopher in
western Washington (Service 2009b, pp. 7-8). The Mazama pocket gopher
is adapting to the presence of many types of nonnative vegetation;
however, the presence of Cytisus scoparius (Scotch broom), which has
large root masses, restricts pocket gopher dispersal. The loss of
prairie habitat to conifer encroachment is also a threat to the Mazama
pocket gopher (Flotlin 2010, pers. comm.). Cytisus scoparius does not
occur within the range of the Wyoming pocket gopher, and conifer
encroachment is limited.
To inform our evaluation of the potential threat from nonnative
species, we looked at the potential for Bromus tectorum (cheatgrass) to
impact Wyoming pocket gopher populations. The conversion from A.
tridentata spp. to B. tectorum has been shown to negatively impact
other small mammals (Yensen et al. 1992, p. 309). The spread of B.
tectorum has the potential to change vegetative communities in a way
that could affect the Wyoming pocket gopher. As discussed previously,
forbs are an important component of pocket gopher diets, and high
densities of B. tectorum reduce the biomass and growth rates of forbs,
as well as seedling survival for some forb species (Parkinson 2008, pp.
37-46). Further, when chemical treatments were used to experimentally
reduce the abundance of weedy forbs in favor of grasses, a northern
pocket gopher population declined roughly in proportion to the loss of
forbs (Keith et al. 1959, p. 231).
Pocket gophers that eat grass species have reduced body weights
(Tietjen et al. 1967, pp. 642-643). Grasses, when not consumed with
other vegetation, do not seem to provide an adequate diet for Thomomys
species (Cox 1989, p. 80). While Bromus tectorum may impact the
abundance of forbs in the species' habitat, B. tectorum may also be
used by Wyoming pocket gophers. Small quantities of the seeds of B.
tectorum have been occasionally found in tunnels of northern pocket
gophers, although seed heads of B. tectorum were not preferred as
forage (Cox 1989, pp. 78-80). Northern pocket gophers also occur at
locations where B. tectorum was considered to be a prevalent plant
species (Ostrow et al. 2002, p. 992). During their breeding season,
Botta's pocket gophers have been found to consume substantial
quantities of species related to B. tectorum, B. mollis (soft brome)
and B. rubens (red brome), when the nutrient content of the plants was
highest (Hunt 1992, p. 49).
While Bromus tectorum appears to have the potential to impact
Wyoming pocket gopher habitat, the spread of B. tectorum throughout the
habitat of the Wyoming pocket gopher is not a foregone conclusion. In
Wyoming, B. tectorum can be locally abundant, but precipitation and
elevation differences influence where B. tectorum occurs (Smith and
Enloe 2006, p. 1). In southern Wyoming counties, the fall precipitation
prior to cold weather needed for B. tectorum germination is generally
rare in zones where 14 inches or less of precipitation is received
annually (Smith and Enloe 2006, p. 1). The annual precipitation within
the range of the Wyoming pocket gopher is generally less than 14 inches
of precipitation annually (National Atlas 2005, unpaginated).
In approximately the last 100 years, no broad-scale B. tectorum
eradication method has been developed. Given the history of invasive
plants on the landscape, the continued challenges in controlling such
species, and the current infestation of invasive plants across the
Wyoming pocket gopher's range, we anticipate that invasive plants will
be on the landscape for the next 100 years or longer. However, studies
indicate B. tectorum germination may be generally rare in Wyoming
pocket gopher habitat, possibly inhibiting the future spread and impact
of this invasive species in Wyoming pocket gopher habitat. In summary,
we could find no information suggesting that nonnative species or B.
tectorum, where it occurs within the occupied range of the Wyoming
pocket gopher, represent a threat to the species now, or in the
foreseeable future.
Climate Change
The Intergovernmental Panel on Climate Change (IPCC) has concluded
that warming of the climate is unequivocal and that continued
greenhouse gas emissions at or above current rates will cause further
warming (IPCC 2007, p. 30). Eleven of the 12 years from 1995 through
2006 rank among the 12 warmest years in the instrumental record of
global surface temperature since 1850 (Independent Scientific Advisory
Board 2007, p. 6). Climate-change scenarios estimate that the mean air
temperature could increase by more than 3 degrees Celsius (5.4 degrees
Fahrenheit) by 2100 (IPCC 2007, p. 46). The IPCC also projects that
there will very likely be regional increases in the frequency of hot
extremes, heat waves, and heavy precipitation (IPCC 2007, p. 46), as
well as increases in atmospheric carbon dioxide (IPCC 2007, p. 36).
Plant species provide habitat and forage that affect the ability of
mammal species, such as the Wyoming pocket gopher, to persist over
time. A variety of plant-related factors are not included in climate
space models, including the effect of elevated carbon dioxide on plant
water-use efficiency, the physiological effect to the species of
exceeding the assumed (modeled) bioclimatic limit, the life stage at
which the limit affects the species (seedling versus adult), the life
span of the species, and the movement of other organisms into the
species' range (Shafer et al. 2001, p. 207). These factors would likely
help determine how climate change would affect plant species
distributions. While more empirical studies are needed on what
determines species and multi-species distributions, those data are
often lacking; in their absence, climatic space models can play an
important role in characterizing the types of changes that may occur so
that the potential impacts on natural systems can be assessed (Shafer
et al. 2001, p. 213).
One study modeled potential climate change impacts to A. tridentata
spp., which are representative of the ecosystem currently known to be
occupied Wyoming pocket gopher habitat (Shafer et al. 2001, pp. 200-
215). Each scenario in the study predicted a reduction in the size of
the overall range of sagebrush and shift where sagebrush may occur.
These simulated changes were the result of increases in the mean
temperature of the coldest month, which the authors speculated may
interact with soil moisture levels to produce the simulated impact.
Each model predicted that climate suitability
[[Page 19601]]
for big sagebrush would shift north into Canada. Other areas within big
sagebrush distributions would become less suitable climatically and
would potentially cause a significant contraction in sagebrush range.
Since the Wyoming pocket gopher is associated with sagebrush in the
matrix that forms Wyoming pocket gopher habitat, contractions of
sagebrush could result in negative effects to the species. However,
although the Wyoming pocket gopher occurs within sagebrush habitats,
the species prefers vegetation other than sagebrush at a finer scale
within that matrix (Griscom et al. 2010, p. 15).
In some cases, effects of climate change can be demonstrated (e.g.,
McLaughlin et al. 2002, p. 6073). Where it can be, we rely on that
empirical evidence, such as increased stream temperatures (see Rio
Grande cutthroat trout, 73 FR 27900, May 14, 2008) or loss of sea ice
(see polar bear, 73 FR 28212, May 15, 2008), and treat it as a threat
that can be analyzed. The degree to which climate change will interact
with ecological processes important to Wyoming pocket gophers is not
currently known.
Based on the evolutionary and ecological response of pocket gopher
species to past global warming and cooling events, changes in
temperature and precipitation may result in phenotypic and density
changes in Wyoming pocket gopher populations (Hadly 1997, p. 292; Hadly
et al. 1998, p. 6896; Barnosky et al. 2003, pp. 360-361), but we have
no information specific to the Wyoming pocket gopher. If the Wyoming
pocket gopher's range experiences increased temperatures and reduced
precipitation in the future, these changes could include reduced body
size and population abundance (Hadly 1997, p. 292). Past climate-
induced, population-level, phenotypic change in pocket gophers was
likely the result primarily of developmental plasticity within
populations and not large-scale migration (Hadly et al. 1998, p. 6896;
Barnosky et al. 2003, p. 362). Measured changes in phenotype and
population size appeared to be an initial response to global warming
episodes, with the extent of change being dependent upon the magnitude
and duration of climatic change (Barnosky et al. 2003, pp. 364-365).
Smaller body size and reduced abundance experienced by historical
pocket gopher populations during global hot, dry periods is likely a
response to reduced food availability during those periods (Hadly 1997,
p. 290). Projected climate change has the potential to significantly
alter the distribution of forage important to pocket gophers through
shifts in timing and amount of precipitation, or through changes in
seasonal high, low, or average temperatures (Bachelet et al. 2001, p.
174). For example, warmer temperatures and greater concentrations of
atmospheric carbon dioxide create conditions favorable to Bromus
tectorum, which outcompetes native vegetation and greatly accelerates
the natural fire cycle in areas where it becomes established (Chambers
and Pellant 2008, p. 31; Global Climate Change Impacts in the United
States 2009, p. 83). Future carbon dioxide emissions from energy use
are projected to increase by 40 to 110 percent between 2000 and 2030
(IPCC 2007, p. 44). If a resulting shift in the vegetative communities
occurs within the range of the Wyoming pocket gopher, the displacement
of native forbs and grasses could significantly alter the availability
of sufficient forage resources. This could then be exacerbated by the
continued loss of those resources as a result of the shortened fire
cycle.
Application of continental-scale climate change models to regional
landscapes and even more local or ``step-down'' models projecting
habitat potential based on climatic factors is informative, but
contains a high level of uncertainty when predicting future effects to
the Wyoming pocket gopher and its habitat due to a variety of factors,
including regional weather patterns, local physiographic conditions,
life stages of individual species, generation time of species, and
species' reactions to changing carbon dioxide levels. The models
summarized above are limited by these types of factors; therefore,
their usefulness in assessing the threat of climate change on the
Wyoming pocket gopher into the future is also limited.
Drought
Drought conditions occur within the range of the Wyoming pocket
gopher and are a natural process that has historically occurred
separately from climate change. We anticipate natural drought cycles to
occur periodically within the range of the Wyoming pocket gopher into
the future. We could find no specific information regarding the effects
of drought on the Wyoming pocket gopher. Presumably drought would
likely affect forage growth and potentially limit food availability.
While this may have temporary effects on population numbers and the
reproductive ability of the Wyoming pocket gopher, the species
continues to occupy its known range despite historic periods of natural
drought.
Summary of Climate Change and Drought
The direct, long-term impact from climate change to the Wyoming
pocket gopher is not known. Shifts in the vegetative community may
affect the species' ability to forage. However, given our lack of
knowledge of important food resources for the Wyoming pocket gopher,
our resulting lack of understanding about how changes in the forage
base may affect the species, and our uncertainty regarding the effects
of climate change on those food resources, we cannot consider climate
change to be a threat to the species now, or in the foreseeable future.
A reduction in forage availability may also occur during periods of
drought. However, we have no data to facilitate our understanding of
what impacts this may have on the species. Additionally, the Wyoming
pocket gopher has persisted within its known range since at least 1857
(Thaeler and Hinesley 1979, p. 480) despite periods of natural drought.
Therefore, while there may be population variation as a result of
drought, we do not have any data indicating that drought creates a
threat to the Wyoming pocket gopher now, or in the foreseeable future.
Grazing
Currently, livestock grazing is the most widespread type of land
use across the sagebrush biome, which includes the known range of the
Wyoming pocket gopher (Knick et al. 2003, p. 616; Connelly et al. 2004,
pp. 7-29; Knick et al., in press, p. 27). Several studies have shown
that livestock grazing can result in reduced pocket gopher abundance
and in some cases complete exclusion (Phillips 1936, p. 676; Hunter
1991, p. 117; Stromberg and Griffin 1996, p. 1205; Eviner and Chapin
2003, p. 125). Livestock grazing has the potential to negatively affect
pocket gophers through a variety of mechanisms, such as soil compaction
(Phillips 1936, pp. 677-678). However, direct competition for forage
likely has the largest negative effect on pocket gopher populations
(Phillips 1936, p. 677). Wild ungulate grazing has been found to have
similar competitive effects to other small mammals (Co[auml]te et al.
2004, p. 129), and this interaction may impact pocket gophers. However,
we have no information to suggest that this competition is occurring
with the Wyoming pocket gopher.
Historically, pocket gophers have been recognized by livestock
producers as competitors with livestock for limited rangeland forage
(Richens 1965, p. 424; Julander et al. 1969, p. 325; Turner
[[Page 19602]]
1969, p. 377; Laycock and Richardson 1975, p. 458). Pocket gophers
primarily feed on forbs; however, diet composition can shift seasonally
to include varying percentages of grasses and shrubs (see discussion
above under Life History; Aldous 1951, pp. 85-86; Ward and Keith 1962,
p. 747). Cattle are grazers, feeding mostly on grasses, but they will
make seasonal use of forbs and shrub species (Vallentine 1990, p. 226).
Domestic sheep are intermediate feeders, making high use of forbs but
also using a large volume of grass and shrub species (Vallentine 1990,
pp. 240-241). Horses are generalists, but seasonally their diets can be
almost wholly comprised of grasses (Wagner 1983, pp. 119-120). The
degree of competition between pocket gophers and livestock due to diet
varies with local conditions that affect type and abundance of
vegetation, stocking rates, and types of livestock (Phillips 1936, p.
676; Eviner and Chapin 2003, p. 125). We are unable to assess the
levels of competition that are occurring, but competition has likely
remained constant since grazing levels on BLM lands have generally been
stable since 1978 (Laycock et al. 1996, p. 50). We anticipate future
levels of competition from grazing to remain constant, as the recently
renewed BLM Resource Management Plan for much of the range of the
Wyoming pocket gopher does not include a change in past livestock
stocking rates (BLM 2008, pp. 2-19).
Domestic livestock grazing will continue at present levels within
the range of the Wyoming pocket gopher (BLM 2008, pp. 2-19). The
current amounts, kinds, and seasons of livestock grazing use will be
authorized until monitoring, field observations, ecological site
inventory, or other data acceptable to the BLM indicates an adjustment
to grazing use is necessary (BLM 2008, pp. 2-19). While we cannot
provide an exact estimate of the foreseeable future for grazing, we
expect this use to be persistent across the Wyoming pocket gopher's
range for several decades.
We recognize the potential for negative impacts to Wyoming pocket
gopher populations due to direct competition with livestock, but have
no information about the impacts of grazing practices or grazing
intensity to the species. Livestock grazing has remained consistent
over time, and the Wyoming pocket gopher has continued to occupy its
known range. Additionally, we are unaware of any studies linking
grazing practices to population levels of the Wyoming pocket gopher.
Therefore, we have no information to indicate that grazing poses a
threat to the Wyoming pocket gopher now, or in the foreseeable future.
Urbanization
Urbanization is considered a significant threat to other species of
pocket gopher, such as the Mazama pocket gopher (Service 2009b, p. 8);
however, urbanization is limited within the range of the Wyoming pocket
gopher. This area is largely rural, with approximately 55,000 people
residing in Carbon and Sweetwater Counties in 2008 (U.S. Census Bureau
2009, p. 94), which is an average of 3 people per square mile (2.6
square kilometers). However, most of this population is concentrated in
the population centers of Rock Springs, Green River, and Rawlins, which
are at the edges of the potential Wyoming pocket gopher range. The BLM
administers approximately half of the land in the range of the species,
so urban development is precluded from those areas. Limited housing
development is occurring near Wyoming pocket gopher collection sites,
primarily to support gas field workers. These areas provide
concentrated areas of disturbance, which create fewer impacts to the
overall range of the species. The limited amount of housing across the
range of the species also restricts the opportunities for domestic pet
predation on Wyoming pocket gophers. We are unable to quantify a
foreseeable future, but anticipate that additional urbanization will be
limited based on the isolated nature of the area and the harsh
environment that has not historically attracted many people. Based on
the limited amount of urbanization, we do not consider it to be a
significant threat to the Wyoming pocket gopher now, or in the
foreseeable future.
Summary of Factor A
We conclude that the range of the Wyoming pocket gopher has
experienced and will continue to experience significant changes,
primarily related to oil, gas, and wind development. The range is also
likely to experience some changes related to climate change. Changes
from other sources, including nonnative vegetation, grazing, and
urbanization, may occur to a lesser degree. However, we are unable to
demonstrate that these alterations to habitat will result in negative
effects to the species. Examining data from studies on other species of
pocket gophers' responses to similar disturbances did not provide
clarity as the response appeared to vary by species. For example, the
invasive Bromus tectorum may negatively affect pocket gophers, but
northern pocket gophers can occur where B. tectorum is a prevalent
plant species (Ostrow et al. 2002, p. 992), and the seeds of B.
tectorum were occasionally found in their burrows (Cox 1989, pp. 78-
80). Many species of pocket gophers increase rates of mound building in
areas of disturbed vegetation, while others are not found in areas of
disturbance (Moulton et al. 1983, p. 58). Therefore, predicting the
potential effects of habitat disturbances or alteration on the Wyoming
pocket gopher based on the responses of other pocket gophers is not
possible. The species continues to occupy its known historic range
despite habitat alterations that have occurred within that range, and
we have no evidence of population declines.
We conclude that the best scientific and commercial information
available indicates that the Wyoming pocket gopher is not now, or in
the foreseeable future, threatened by the present or threatened
destruction, modification, or curtailment of its habitat or range to
the extent that listing under the Act as an endangered or threatened
species is warranted at this time.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Overutilization is the consumptive use of an organism, where
individuals are intentionally captured or taken for a variety of
purposes. Examples include take for human consumption, use of feathers
or fur to create garments, and capture and removal of individuals for
scientific or educational examinations or study. We have no data
indicating that the Wyoming pocket gopher has been, is currently being,
or will be in the future, used for commercial, recreational, or
educational purposes.
In the late 1970s, in Wyoming and Colorado, 228 pocket gophers of
three different species were collected and euthanized to collect tissue
for taxonomic delineation (Thaeler and Hinesley 1979, p. 480). Forty of
the animals collected were identified as Wyoming pocket gophers,
although the authors note that tissue preparation on 83 individuals was
insufficient to do genetic analyses. Therefore, more Wyoming pocket
gophers may have been collected but not identified. No further
documented captures of the Wyoming pocket gopher occurred until 2008,
when 12 individuals were trapped to collect genetic and morphological
information for species determination (Griscom et al. 2010, p. 5). Two
of those pocket gophers were euthanized to obtain the tissue necessary
for karyotyping procedures (McDonald 2009b, pers. comm.). Trapping
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continued in 2009 to collect distribution and habitat information. A
total of 19 individuals were captured in 2009 (Griscom 2010b, pers.
comm.), with 2 individuals found dead in the traps (Griscom et al.
2010, p. 9). No other Wyoming pocket gopher mortalities from these
trapping efforts were reported. Tissue samples (removing the tip of the
tail) were collected from 5 individuals in 2008 and 15 individuals in
2009 prior to their subsequent release at the capture location (Griscom
2009c, pers. comm.; Griscom et al. 2010, p. 22). Some individuals may
have died after release at the capture location; however, one Wyoming
pocket gopher (Griscom 2009c, pers. comm.) and a pocket gopher of
another species were recaptured a day or two after the tip of the tail
was removed (Griscom et al. 2010, p. 11). The wounds were healing, and
the pocket gophers did not appear to show any ill effects (Griscom et
al. 2010, p. 11). Northern pocket gophers survived in a lab environment
for several weeks after having their tails clipped (McDonald 2009a,
pers. comm.). This limited evidence suggests that this tissue
collection does not result in mortality.
The Wyoming Game and Fish Department (WGFD) issued collection
permits for Wyoming pocket gophers for the scientific work that
occurred in 2008 and 2009 (Emmerich 2009, p. 2). The review associated
with the permitting process provided a protective measure to the
species by limiting take to those individuals authorized to perform the
work (Wyoming Game and Fish Commission (WGFC) 1998, pp. 52-8-52-9).
Based on recent interest in the Wyoming pocket gopher, we anticipate
that some utilization of the species related to scientific research
will occur in 2010 and possibly in future years.
We could find no other information on research or scientific use of
the Wyoming pocket gopher. The lack of population data for this species
results in difficulties in determining whether the Wyoming pocket
gopher is adversely impacted by scientific purposes. However, we do not
believe overutilization to be a current or future threat because
relatively few individuals have been affected by scientific research,
research methodologies generally involve live captures, and available
information indicates captured individuals can survive without
noticeable effects.
Summary of Factor B
We conclude that the best scientific and commercial information
available indicates that the Wyoming pocket gopher is not now, or in
the foreseeable future, threatened by overutilization for commercial,
recreational, scientific, or educational purposes to the extent that
listing under the Act as an endangered or threatened species is
warranted at this time.
Factor C. Disease or Predation
Disease and parasites have not been demonstrated to limit
populations of pocket gophers (Keinath and Beauvais 2006, p. 20). In
general, pocket gophers host some endo- and exo-parasites, most of
which have been identified incidentally to other research (Keinath and
Beauvais 2006, p. 21). In some cases, northern pocket gophers have been
found with sufficient levels of botfly larvae to result in mortality,
with up to 25 to 37 percent of local gopher populations affected
(Keinath and Beauvais 2006, p. 21 and references therein). However, the
effects of these infestations on population persistence were not
provided. No research has been conducted on diseases and parasites of
the Wyoming pocket gopher. Therefore, combined with the lack of
population data, we have no way of assessing the current or future
impact of this factor on this species. We recognize that lower levels
of genetic diversity may allow a population to have greater
susceptibility to diseases (Sanjayan et al. 1996, p. 1525), but we do
not have information indicating that disease poses a threat to the
Wyoming pocket gopher, and we do not have sufficient information to
describe genetic diversity of the species. Additionally, we do not have
information indicating that human activities in the area increase the
susceptibility of the Wyoming pocket gopher to disease or parasites due
to increased physiological stress.
Pocket gophers are subject to predation from gopher snakes
(Pituophis catenifer), rattlesnakes (Crotalus viridis), long-tailed
weasels (Mustela frenata), coyotes (Canis latrans), bobcats (Lynx
rufus), badgers (Taxidea taxus), foxes (Vulpes spp.), skunks (Mephitis
spp.), numerous owls (Keinath and Beauvais 2006, p. 20), and domestic
pets (Stinson 2005, p. 51). However, we have no data indicating that
predation limits Wyoming pocket gopher populations. Ravens (Corvus
corax) use road networks associated with oil fields in southwestern
Wyoming for foraging activities (Bui 2009, p. 31), and common raven
abundance increases in association with oil and gas development in
southwestern Wyoming (Holmes 2009, p. 1). However, we could find no
information that ravens prey upon pocket gophers. Therefore, if raven
abundance is increasing within the range of the Wyoming pocket gopher
as a result of energy development activities, there is likely no effect
on Wyoming pocket gophers. We were unable to find any other information
to suggest that the predator-prey balance for the Wyoming pocket gopher
has been affected by any anthropogenic activity, or may be affected
within the forseeable future.
Based on our understanding of past and current effects, we do not
anticipate the effects of disease, parasites, or predation to change
for the foreseeable future.
Summary of Factor C
We conclude that the best scientific and commercial information
available indicates that the Wyoming pocket gopher is not now, or in
the foreseeable future, threatened by disease or predation to the
extent that listing under the Act as an endangered or threatened
species is warranted at this time.
Factor D: The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether identified threats to the
Wyoming pocket gopher are adequately addressed by existing regulatory
mechanisms. These mechanisms could include: (1) Local land use laws,
processes, and ordinances; (2) State laws and regulations; and (3)
federal laws and regulations. Regulatory mechanisms, if they exist, may
preclude listing if such mechanisms are judged to adequately address
the threat to the species such that listing is not warranted.
We could find no local land use laws, processes, or ordinances that
provide a regulatory mechanism for the Wyoming pocket gopher. The State
of Wyoming has identified the Wyoming pocket gopher as a Native Species
Status 4, meaning that while populations are restricted in
distribution, the species' habitat does not appear to be declining, and
there are no known sensitivities to human disturbance (Oakleaf et al.
2002, p. 263). Important conservation efforts for this species
identified by the WGFD are to collect more information on the species'
status, trends, and habitat use. The Wyoming pocket gopher is
identified in the WGFD Comprehensive Wildlife Conservation Strategy
(WGFD 2005, pp. 250-251) as a species of concern, which signifies a
decline or restriction to the population or its habitat or both, but
confers no State protection to the species. The Wyoming pocket gopher
received this designation based on restricted habitat and limited
available information on the species (Emmerich 2009, p. 1). The WGFD
does
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restrict the take of the Wyoming pocket gopher under Chapter 52 of the
WGFC regulations (WGFC 1998, p. 52-9; Emmerich 2009, p. 1). This
designation protects individuals of the species from take unless take
is authorized by regulations or is necessary to address human health or
safety (WGFC 1998, pp. 52-58). No state regulatory mechanisms provide
for protection of the species' habitat.
The Wyoming pocket gopher has been identified as a sensitive
species by Region 2 of the U.S. Forest Service (USFS) based on the
species' rarity and potential sensitivity to disturbance (Keinath and
Beauvais 2006, p. 6; USFS 2006, p. 10), although we are unaware of any
occurrence of this species on USFS lands (Keinath and Beauvais 2006, p.
7). The USFS does not confer any protective regulations to identified
sensitive species. The BLM in Wyoming also identifies the Wyoming
pocket gopher as a sensitive species (Abbott 2009b, pers. comm.), which
requires the agency to consider the welfare of these species when
evaluating any action on public lands (BLM 2001, pp. 21J-22D3c(2)). The
BLM has identified the Wyoming pocket gopher in NEPA documents in the
areas of the Wyoming pocket gopher's distribution, such as the 2006
Atlantic Rim Final Environmental Impact Statement (BLM 2006b, p. 4-89).
Project proponents for future projects on BLM lands were instrumental
in collecting distributional data in 2008 and 2009 (Beauvais 2009, p.
4; Griscom et al. 2010, p. 6). However, species-specific management
actions have not been developed by the BLM (Keinath and Beauvais 2006,
pp. 6-8; Abbott 2010, pers. comm.). Despite the lack of regulatory
mechanisms, this species continues to occupy its known range.
We anticipate no changes in the current regulatory mechanisms for
the foreseeable future, unless research on the Wyoming pocket gopher
indicates that regulatory mechanisms are necessary and can help
prescribe specific effective protections.
Summary of Factor D
We conclude that the best scientific and commercial information
available indicates that the Wyoming pocket gopher is not now, or in
the foreseeable future, threatened by the inadequacy of existing
regulatory mechanisms to the extent that listing under the Act as an
endangered or threatened species is warranted at this time. It is
unclear that regulatory mechanisms in addition to those described are
needed for the species based on the current understanding of threats.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Other natural or manmade factors affecting the continued existence
of the Wyoming pocket gopher that we analyzed include vulnerability of
small populations, use of poisons to target the species, and
recreational activities. We are unaware of other factors that may
affect the continued existence of the species.
Vulnerability of Small Populations
The Wyoming pocket gopher is a narrow endemic species (i.e., a
species whose natural occurrence is confined to a certain region and
whose distribution is relatively limited). The best available
scientific data suggest that this species occurs in just two counties
in southwest Wyoming. Small geographic range has been identified as the
most important single indicator of elevated extinction risk in mammals
(Purvis et al. 2000, p. 1949; Oborny et al. 2005, p. 291; Cardillo et
al. 2006, pp. 4157-4158; Cardillo et al. 2008, p. 1445; Davies et al.
2008, p. 11559). The inherent vulnerability associated with small
geographic range is due to the fact that a single localized threat,
whether it is manmade (e.g., development) or environmental (e.g.,
disease), can potentially impact the entire distribution of the
species, resulting in an increased probability of extinction (Davies et
al. 2008, p. 11559).
Small population size has also been identified as an important
predictor of extinction vulnerability (O'Grady et al. 2004, p. 517).
Although we have no information on Wyoming pocket gopher abundance,
restricted geographic range frequently correlates with small population
size (Purvis et al. 2000, p. 1947). Thus, it is reasonable to assume
that abundance is low relative to other pocket gopher species with
larger geographic ranges (e.g., northern pocket gopher). Given their
restricted distribution and presumably relatively small population
size, Wyoming pocket gophers are more vulnerable to demographic,
environmental, and genetic stochasticity than larger, more widely
distributed species, which could affect the Wyoming pocket gopher's
likelihood for long-term persistence.
Wyoming pocket gopher distribution appears to be discontinuous, and
it remains undetermined if a metapopulation structure (a group of
spatially separated populations which interact at some level) exists
for this species (Keinath and Beauvais 2006, p. 19). Based on the
abilities of other pocket gophers, which is consistent in the
scientific literature for all species, Wyoming pocket gophers are not
thought capable of dispersing long distances and may be restricted by
the energetic demands of tunneling (Hansen 1962, p. 152; Vaughan 1963,
p. 371; Keinath and Beauvais 2006, p. 16). There may be some above-
ground dispersal at night (Griscom 2009a, pers. comm.) or when there is
snow cover (Vaughan 1963, p. 369). The patchy distribution and low
dispersal capability result in a low probability for recolonization
following local population extinctions (Keinath et al. 2008, p. 7).
When the area over which a colonization-extinction process operates is
geographically small, as is the case with Wyoming pocket gopher, a
single local extinction that is not followed by recolonization can have
a large impact on the occupancy of the total area (Oborny et al. 2005,
p. 291).
The Wyoming pocket gopher has persisted since at least 1857 (Coues
1875, p. 138) and may never have had a large population size. The
species appears to be currently distributed throughout its known range
in a pattern that approximates historic distribution (see Figure 1
above). However, it appears to have several characteristics, such as
small geographic range, isolated populations, and low dispersal
ability, which increase the species' vulnerability to extinction from
stochastic events and other threats on the landscape. Currently, we do
not have information on these threats to an extent that allows us to
know whether small population size allows for other manmade or
environmental factors to create a threat to the Wyoming pocket gopher.
Further, the historic range and persistence of the species' population
size indicate the species occurs in normally low population densities.
We are unable to quantify a foreseeable future for stochastic events
that may have disproportionate negative effects on small population
sizes. We do not anticipate the effects of these events on small
population size to change, but our understanding of these effects may
improve over time.
Lethal Control of Pocket Gophers
Campaigns to eliminate other species of pocket gophers are often
pursued in association with development, farmlands, and ranchlands. We
have no information that indicates that pocket gophers are the target
of lethal control campaigns within the range of the Wyoming pocket
gopher. Strychnine and Rozol are both rodenticides approved by the U.S.
Environmental Protection Agency for control of pocket gophers, and
these substances may
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create a threat to the Wyoming pocket gopher through targeted
application or non-target poisonings of another species (Dickerson
2009a, pers. comm.). We are unable to show the extent to which these
and similar substances are used on private lands in the area; however,
rangelands, which form the majority of Wyoming pocket gopher habitat,
are not typically the target of pocket gopher control measures
(Dickerson 2009b, pers. comm.). Additionally, the BLM does not use
pesticides or rodenticides in Wyoming to protect reclamation areas
(Abbott 2009a, pers. comm.). We are unable to determine if the Wyoming
pocket gopher may be targeted by, or exposed to, substances used for
lethal control in the future. We are unaware of other methods that are
commonly used for lethal control of pocket gopher populations. We
currently do not have any information that would lead us to anticipate
an increase in lethal control of the Wyoming pocket gopher for the
foreseeable future.
Recreational Activities
Recreational activities within the range of the Wyoming pocket
gopher include hunting, camping, hiking, horse riding, use of all-
terrain vehicles, and visiting historic sites. These activities may
cause elevated levels of human presence on the landscape and resultant
disturbances to habitat, which were discussed in Factor A. We have no
information to indicate that increased human presence related to
recreation poses a threat to the Wyoming pocket gopher. We anticipate
that recreational activities will continue at current or slightly
increased levels within the range of the Wyoming pocket gopher for the
foreseeable future.
Summary of Factor E
Based on the best available information, we have no indication that
other natural or manmade factors are likely to significantly threaten
the existence of the species. We recognize the inherent vulnerabilities
of small populations and restricted geographic range, which appear to
be exhibited by the Wyoming pocket gopher. The impacts of various
potential threats can be more pronounced on small or isolated
populations, and we have identified numerous activities occurring on
the landscape within the range of the Wyoming pocket gopher (see Factor
A discussion). However, at this time, we do not have information to
indicate that these activities pose a threat to the Wyoming pocket
gopher. Additionally, we do not consider a small population alone to be
a threat to species; rather, it can be a vulnerability that can make it
more susceptible to threat factors, if they are present. Many naturally
rare species have persisted for long periods within small geographic
areas, and many naturally rare species exhibit traits that allow them
to persist despite their small population sizes (Nevo et al. 1997, p.
388; Rubinoff and Powell 2004, p. 2547; Lawson et al. 2008, p. 927;
Abeli et al. 2009, p. 3887). The Wyoming pocket gopher is one of these
species, existing in a limited range since its discovery in 1857. We
have no information that this rarity is working in combination with any
threat factors that would cause the species to be likely to become in
danger of extinction in all or a significant portion of its range in
the foreseeable future. We have identified lethal control of pocket
gophers and recreational activities as other manmade factors that may
impact the species, but we have no information that these factors are
negatively impacting the species at this time.
We conclude that the best scientific and commercial information
available indicates that the Wyoming pocket gopher is not now, or in
the foreseeable future, threatened by other natural or manmade factors
affecting its continued existence to the extent that listing under the
Act as an endangered or threatened species is warranted at this time.
Finding
As required by the Act, we considered the five factors in assessing
whether the Wyoming pocket gopher is endangered or threatened
throughout all or a significant portion of its range. We have carefully
examined the best scientific and commercial information available
regarding the status and the past, present, and future threats faced by
the Wyoming pocket gopher. We reviewed the petition, information
available in our files, and other published and unpublished information
submitted to us by the public following our 90-day petition finding. We
also consulted with Wyoming pocket gopher experts and other Federal and
State resource agencies. In considering what factors might constitute
threats, we must look beyond the mere exposure of the species to the
factor to determine whether the species responds to the factor in a way
that causes actual impacts to the species. If there is exposure to a
factor, but no response, or only a positive response, that factor is
not a threat. If there is exposure and the species responds negatively,
the factor may be a threat and we then attempt to determine how
significant a threat it is. If the threat is significant, it may drive
or contribute to the risk of extinction of the species such that the
species warrants listing as threatened or endangered as those terms are
defined by the Act. This does not necessarily require empirical proof
of a threat. The combination of exposure and some corroborating
evidence of how the species is likely impacted could suffice. The mere
identification of factors that could impact a species negatively is not
sufficient to compel a finding that listing is appropriate; we require
evidence that these factors are operative threats that act on the
species to the point that the species meets the definition of
threatened or endangered under the Act. We were able to quantify the
foreseeable future only for energy development and scientific
utilization of the species, but discussed how we anticipate each factor
to change over time. We were unable to project changes to the species
into the future because we do not have sufficient data to know if these
factors will result in positive or negative effects to the species.
Our review of the best available scientific and commercial
information pertaining to the five factors does not support the
assertion that there are threats of sufficient imminence, intensity, or
magnitude to indicate the Wyoming pocket gopher is in danger of
extinction (endangered), or is likely to become endangered within the
foreseeable future (threatened), throughout all or a significant
portion of its range. Therefore, we find that listing the Wyoming
pocket gopher throughout all or a significant portion of its range is
not warranted at this time.
In making this finding, we recognize that the Wyoming pocket
gopher, despite not being warranted for listing as endangered or
threatened, may benefit from increased management emphasis due to its
limited distribution and range. In particular, future oil, gas, and
wind development may have positive or negative impacts to the species
and should be carefully considered and monitored. We recommend
precautionary measures be taken to protect the species, and that
additional research be pursued to improve the understanding of the
species so that the responses to future potential threats can be better
understood.
Distinct Vertebrate Population Segments
After assessing whether the species is endangered or threatened
throughout its range, we next consider whether a distinct vertebrate
population segment (DPS) of the Wyoming pocket gopher meets the
definition of endangered or is likely to become endangered in the
foreseeable future (threatened).
[[Page 19606]]
Under the Service's Policy Regarding the Recognition of Distinct
Vertebrate Population Segments Under the Endangered Species Act (61 FR
4722, February 7, 1996), three elements are considered in the decision
concerning the establishment and classification of a possible DPS.
These are applied similarly for additions to or removals from the
Federal List of Endangered and Threatened Wildlife. These elements
include: (1) The discreteness of a population in relation to the
remainder of the taxon to which it belongs; (2) the significance of the
population segment to the taxon to which it belongs; and (3) the
population segment's conservation status in relation to the Act's
standards for listing, delisting (removal from the list), or
reclassification (i.e., is the population segment endangered or
threatened).
As stated above, the Wyoming pocket gopher is a narrow endemic
species, historically and currently found in only two counties in
south-central Wyoming. Only 47 confirmed Wyoming pocket gophers have
been trapped over approximately the past 40 years, and the species
appears to be currently distributed throughout its known range in a
pattern that approximates historic distribution (see Figure 1 above).
Dispersal strategies of the Wyoming pocket gopher are unknown (see
discussion under Life History above). However, in other species of
pocket gophers, dispersal has been well documented (e.g., Daly and
Patton 1990, p. 1291; Hafner et al. 1998, p. 281), and we have no
evidence to suggest that the Wyoming pocket gopher does not disperse
within its known range. Therefore, we have no evidence suggesting that
the Wyoming pocket gopher is isolated in any part of its range. We
determine, based on a review of the best available information, that no
portion of the Wyoming pocket gopher range meets the discreteness
conditions of the 1996 DPS policy. The DPS policy is clear that
significance is analyzed only when a population segment has been
identified as discrete. Since we found that no population segment meets
the discreteness element, and therefore no population segment qualifies
as a DPS under the Service's DPS policy, we will not conduct an
evaluation of significance.
Significant Portion of the Range
Having determined that the Wyoming pocket gopher does not meet the
definition of an endangered or threatened species throughout its entire
region, we must next consider whether there are any significant
portions of the range where the Wyoming pocket gopher is in danger of
extinction or is likely to become endangered in the foreseeable future.
On March 16, 2007, a formal opinion was issued by the Solicitor of
the Department of the Interior (USDI), ``The Meaning of `In Danger of
Extinction Throughout All or a Significant Portion of Its Range'''
(USDI 2007, entire). We have summarized our interpretation of that
opinion and the underlying statutory language below. A portion of a
species' range is significant if it is part of the current range of the
species and it contributes substantially to the representation,
resiliency, or redundancy of the species. The contribution must be at a
level such that its loss would result in a decrease in the ability to
conserve the species.
In determining whether a species is endangered or threatened in a
significant portion of its range, we first identify any portions of the
range of the species that warrant further consideration. The range of a
species can theoretically be divided into portions in an infinite
number of ways. However, there is no purpose to analyzing portions of
the range that are not reasonably likely to be significant and
endangered or threatened. To identify only those portions that warrant
further consideration, we determine whether there is substantial
information indicating that: (1) The portions may be significant, and
(2) the species may be in danger of extinction there or likely to
become so within the foreseeable future. In practice, a key part of
this analysis is whether the threats are geographically concentrated in
some way. If the threats to the species are essentially uniform
throughout its range, no portion is likely to warrant further
consideration. Moreover, if any concentration of threats applies only
to portions of the species' range that are not significant, such
portions will not warrant further consideration.
If we identify portions that warrant further consideration, we then
determine whether the species is endangered or threatened in these
portions of its range. Depending on the biology of the species, its
range, and the threats it faces, the Service may address either the
significance question or the status question first. Thus, if the
Service considers significance first and determines that a portion of
the range is not significant, the Service need not determine whether
the species is endangered or threatened there. Likewise, if the Service
considers status first and determines that the species is not
endangered or threatened in a portion of its range, the Service need
not determine if that portion is significant. However, if the Service
determines both that a portion of the range of a species is significant
and that the species is endangered or threatened there, the Service
will specify that portion of the range as endangered or threatened
under section 4(c)(1) of the Act.
The terms ``resiliency,'' ``redundancy,'' and ``representation''
are intended to be indicators of the conservation value of portions of
the range. Resiliency of a species allows the species to recover from
periodic disturbance. A species will likely be more resilient if large
populations exist in high-quality habitat that is distributed
throughout the range of the species in such a way as to capture the
environmental variability found within the range of the species. A
portion of the range of a species may make a meaningful contribution to
the resiliency of the species if the area is relatively large and
contains particularly high-quality habitat, or if its location or
characteristics make it less susceptible to certain threats than other
portions of the range. When evaluating whether or how a portion of the
range contributes to resiliency of the species, we evaluate the
historical value of the portion and how frequently the portion is used
by the species, if possible. In addition, the portion may contribute to
resiliency for other reasons--for instance, it may contain an important
concentration of certain types of habitat that are necessary for the
species to carry out its life-history functions, such as breeding,
feeding, migration, dispersal, or wintering.
Redundancy of populations may be needed to provide a margin of
safety for the species to withstand catastrophic events. This does not
mean that any portion that provides redundancy is necessarily a
significant portion of the range of a species. The idea is to conserve
enough areas of the range such that random perturbations in the system
act on only a few populations. Therefore, each area must be examined
based on whether that area provides an increment of redundancy that is
important to the conservation of the species.
Adequate representation ensures that the species' adaptive
capabilities are conserved. Specifically, the portion should be
evaluated to see how it contributes to the genetic diversity of the
species. The loss of genetically based diversity may substantially
reduce the ability of the species to respond and adapt to future
environmental changes. A peripheral population may contribute
meaningfully to representation if there is evidence that it provides
genetic diversity due to
[[Page 19607]]
its location on the margin of the species' habitat requirements.
Section 4(c)(1) of the Act requires the Service to determine
whether a portion of a species' range, if not all, meets the definition
of endangered or threatened. As stated above, based on the best
scientific information, we find listing the Wyoming pocket gopher
across its entire range is not warranted. We were unable to identify
any significant portion of the range that merits additional analysis.
The 31 Wyoming pocket gopher captures that occurred in 2008 and 2009
indicate that the species is currently distributed throughout its known
historic range (see Figure 1 above). The limited information available
on the Wyoming pocket gopher, such as the lack of population numbers
and dynamics, does not allow us to determine what portion of the range,
if any, contributes substantially and differentially to the long-term
persistence of the species. As discussed previously, we do not know how
the species is likely to respond to many potential threats (e.g., wind
energy), and therefore we cannot determine if the potential threats
imperil a significant portion of the species' range. Further, for those
potential threats with more well-understood impacts to the species
(e.g., poisoning), we could find no portion of the range in which
threats are concentrated or otherwise likely to impact a significant
portion of the species' range.
Conclusion
We do not find that the Wyoming pocket gopher is in danger of
extinction now, nor is it likely to become endangered within the
foreseeable future, throughout all or a significant portion of its
range. Therefore, listing the species as endangered or threatened under
the Act is not warranted at this time.
We request that you submit any new information concerning the
status of, or threats to, the Wyoming pocket gopher to our Wyoming
Ecological Services Field Office (see ADDRESSES section) whenever it
becomes available. New information will help us monitor this species
and encourage its conservation. If an emergency situation develops for
the Wyoming pocket gopher or any other species, we will act to provide
immediate protection.
References Cited
A complete list of all references cited in this document is
available on the Internet at http://www.regulations.gov and upon
request from the Wyoming Ecological Services Field Office (see
ADDRESSES section).
Author
The primary authors of this document are staff members of the
Wyoming Ecological Services Field Office (see ADDRESSES section).
Authority
The authority for this action is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: March 30, 2010.
Daniel M. Ashe,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2010-8578 Filed 4-14-10; 8:45 am]
BILLING CODE 4310-55-S