[Federal Register Volume 77, Number 188 (Thursday, September 27, 2012)]
[Proposed Rules]
[Pages 59357-59371]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-23739]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2010-0077; 4500030113]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List Spring Mountains Acastus Checkerspot Butterfly as
an Endangered or Threatened Species
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 Spring Mountains acastus
checkerspot butterfly (Chlosyne acastus robusta) as an endangered
species under the Endangered Species Act of 1973, as amended (Act).
After review of the best available scientific and commercial
information, we find that listing the Spring Mountains acastus
checkerspot butterfly is not warranted at this time. However, we ask
the public to submit to us any new information that becomes available
concerning the threats to the Spring Mountains acastus checkerspot
butterfly or its habitat at any time.
DATES: The finding announced in this document was made on September 27,
2012.
ADDRESSES: This finding is available on the internet at http://www.regulations.gov at Docket Number FWS-R8-ES-2010-0077. 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, Nevada Fish and Wildlife Office, 4701 North
Torrey Pines Drive, Las Vegas, NV 89130. Please submit any new
information, materials, comments, or questions concerning this finding
to the above street address.
FOR FURTHER INFORMATION CONTACT: Edward D. Koch, Field Supervisor,
Nevada Fish and Wildlife Office (see ADDRESSES); by telephone at 775-
861-6300; or by facsimile at 775-861-6301. If you use a
telecommunications device for the deaf (TDD), please call the Federal
Information Relay Service (FIRS) at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires
that, for any petition to revise the Federal Lists of Threatened and
Endangered Wildlife and Plants that contains substantial scientific or
commercial information that listing a species may be warranted, we make
a finding within 12 months of the date of receipt of the petition. In
this finding we will 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 an endangered
or threatened species, 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 September 18, 2009, we received a petition dated September 16,
2009, from Bruce M. Boyd requesting that the Spring Mountains acastus
checkerspot butterfly (Chlosyne acastus robusta) be listed as an
endangered species under the Act. Included in the petition was
information regarding the species' taxonomy, historical and current
distribution, present status, and potential causes of decline. We
acknowledged the receipt of the petition in a letter to Bruce M. Boyd,
dated November 24, 2009. In that letter, we responded that we had
reviewed the information presented in the petition and determined that
issuing an emergency regulation temporarily listing the butterfly under
section 4(b)(7) of the Act was not warranted (Service 2009, p. 1). We
also stated that funding was secured and that we anticipated making an
initial finding in fiscal year 2010 as to whether the petition
contained substantial information indicating that the action may be
warranted. On April 13, 2011, we published a 90-day petition finding
(76 FR 20613) in which we concluded that the petition and information
in our files provided substantial information indicating that listing
the Spring Mountains acastus checkerspot butterfly may be warranted,
and we initiated a status review. This notice constitutes the 12-month
finding on the September 16, 2009, petition to list the Spring
Mountains acastus checkerspot butterfly.
[[Page 59358]]
Taxonomy and Subspecies Description
William Henry Edwards (1874, pp. 16-17) provided the first
descriptions of the sagebrush checkerspot butterfly (Chlosyne acastus
(= Melitaea acastus)) from specimens collected during the Hayden
expedition of 1871, Wheeler expedition of 1872, and by Henry Edwards,
Esq. (Brown 1966, pp. 402-405). Specimens collected earlier by Edwards
and named Melitaea sterope (Edwards 1870, pp. 190-191) were considered
a subspecies of northern checkerspot butterfly (Chlosyne palla), but
were subsequently considered conspecific with sagebrush checkerspot
butterflies (Pelham 2008, p. 379). Other synonyms of the genera
Chlosyne used with the species acastus have included Charidryas and
Lemonias (Dyar 1903, pp. 17-18; Opler and Warren 2003, pp. 35-36;
Pelham 2008, pp. 379-380).
Since Edwards' first descriptions of the species in 1870 and 1874,
nine subspecies of sagebrush checkerspot butterfly have been named and
are listed by Pelham in ``A catalogue of the butterflies of the United
States and Canada with a complete bibliography of the descriptive and
systematic literature'' published in volume 40 of the Journal of
Research on the Lepidoptera (2008, pp. 379-380). The common names,
acastus and sagebrush checkerspot butterflies, have been used
interchangeably in the literature for species and subspecies; however,
throughout this finding sagebrush checkerspot butterfly will be used to
reference the species (Chlosyne acastus) and acastus checkerspot
butterfly will be used to reference the subspecies (C. a. acastus). The
other subspecies in the 2008 Pelham catalogue include: no common name
(C. a. arkanyon); Dorothy's checkerspot butterfly (C. a. dorothyi);
Neumoegen's checkerspot butterfly (C. a. neumoegeni); Spring Mountains
acastus checkerspot butterfly (C. a. robusta); Sabina checkerspot
butterfly (C. a. sabina); no common name (C. a. sterope); Death Valley
checkerspot butterfly (C. a. vallismortis); and no common name (C. a.
waucoba) (Bauer 1975, pp. 157-158; Garth and Tilden 1986, p. 82;
Davenport 2004, p. 15; Pelham 2008, pp. 379-380).
Large expanses of desert geographically separate the Spring
Mountains acastus checkerspot butterfly from all other sagebrush
checkerspot butterfly populations and subspecies, with the exception of
Neumoegen's checkerspot butterflies, which have a range that is
adjacent to the Spring Mountains acastus checkerspot butterfly (Austin
1998, p. 577). Biologically, the Spring Mountains acastus checkerspot
butterfly is largely separated from the Neumoegen's checkerspot
butterfly by different flight periods with only a brief period of
potential overlap. Neumoegen's checkerspot butterflies have previously
been considered a distinct species (Ehrlich and Ehrlich 1961, p. 135;
dos Passos 1969, p. 118; Bauer 1975, p. 158; Austin and Austin 1980, p.
40). In addition to a later flight period, Neumoegen's checkerspot
butterflies use different larval host plants than Spring Mountains
acastus checkerspot butterflies (Austin and Leary 2008, p. 102). While
this may currently assist with classifications (Ackery 1988, pp. 95-
203), the use of larval host plants to identify butterflies to the
species or subspecies level may not be conclusive because host plant
relationships may be evolutionarily dynamic, meaning that host plant
use may change during the evolutionary process (Wahlberg 2001, p. 530).
Details of Spring Mountains acastus checkerspot butterfly's biology and
life history are provided below.
Subspecies of adult sagebrush checkerspot butterflies have similar
morphological characteristics. The wingspan of adult sagebrush
checkerspot butterfly species may range from 1.2-1.5 inches (in) (3.0-
3.8 centimeters (cm)) (Opler 1999, p. 299). The upperside of the wing
is a spider-web-like pattern of orange and black (Layberry et al. 1998,
p. 187). The hindwing underside has bands of mostly creamy white and
orange-red spots (Layberry et al. 1998, p. 187) with dark margins. The
forewing underside is primarily orange. In addition, male and female
sagebrush checkerspot butterflies are similar in appearance (Layberry
et al. 1998, p. 187). While there are similarities amongst the
subspecies of sagebrush checkerspot butterflies, there are subtle
variations, which were described by Austin 1998 (p. 577), that
distinguish the Spring Mountains acastus checkerspot butterfly from
other nearby subspecies.
In his description of the adult Spring Mountains acastus
checkerspot butterfly, Austin 1998 (p. 577) compares it to the acastus
checkerspot butterfly, Death Valley checkerspot butterfly, and the
Neumoegen's checkerspot butterfly. Compared to the acastus checkerspot
butterfly, the Spring Mountains acastus checkerspot butterfly is
described as being larger in size, having a more orange than yellow
aspect, and having broader black marks and less basal black on the
upperside of the hindwing (Austin 1998, p. 577). The Spring Mountains
acastus checkerspot butterfly has less contrast than the acastus
checkerspot butterfly between the darker and paler orange areas on both
surfaces, especially for females (Austin 1998, p. 577). In addition,
the Spring Mountains acastus checkerspot butterfly is described as
having a deeper yellow in the pale areas on the underside of the
hindwing than the acastus checkerspot butterfly (Austin 1998, p. 577).
Compared to the Death Valley checkerspot butterfly, the Spring
Mountains acastus checkerspot butterfly is larger and deeper orange
with less contrast (Austin 1998, p. 577). The Death Valley checkerspot
butterfly is yellowish-orange with narrower black markings than the
Spring Mountains acastus checkerspot butterfly (Austin 1998, p. 577).
The underside of the Spring Mountains acastus checkerspot butterfly has
a heavier black pattern towards the outside edge of the wings and has a
more orange color, which appears more washed out (Austin 1998, p. 577).
In addition, the lines of checkerspot pattern on the underside near the
base of the hindwing are thicker in the Spring Mountains acastus
checkerspot butterfly than the Death Valley checkerspot butterfly
(Austin 1998, p. 577).
Compared to the Spring Mountains acastus checkerspot butterfly, the
Neumoegen's checkerspot butterfly is paler orange with narrower or
inconspicuous to absent black lines that run across the wing (Austin
1998, p. 577). In addition the Neumoegen's checkerspot butterfly has
more brilliant pale white areas on the underside of the hindwing than
the deeper yellow of the Spring Mountains acastus checkerspot butterfly
(Austin 1998, p. 577).
The similarities in appearance among and between species of
checkerspot butterflies (for example, Chlosyne acastus, C. gabbii, C.
palla, and C. whitneyi) have led to challenges in distinguishing
species and subspecies (Higgins 1960, pp. 395, 421, 426; Ehrlich and
Ehrlich 1961, p. 132; Ferris and Brown 1981, pp. 325-326; Scott 1986,
pp. 305-307). In addition, there have been specific conflicting
taxonomic views about the sagebrush checkerspot butterflies in the
Spring Mountains (Austin and Austin 1980, p. 40; Austin 1981, p. 71;
Austin 1985, p. 108; Bauer 1975, pp. 155-156; Britten et al. 1993, p.
133; Emmel et al. 1998, pp. 141-142; Higgins 1960, p. 428; Kons 2000,
p. 532).
Austin recognized the Spring Mountains acastus checkerspot
butterfly (Chlosyne acastus robusta) as a distinct subspecies based on
differences in size and wing color characteristics (Austin 1998, pp.
576-577). Austin (1998, p. 576) notes that distinct phenotypes of C.
acastus are present in certain montane
[[Page 59359]]
populations, which provide the context for the designation of
subspecies. Another study used phylogenetic, morphological,
distributional, and biological information to taxonomically evaluate
the Spring Mountains acastus checkerspot butterfly (Kons 2000, p. 2).
Kons (2000, pp. 549-555) did not recognize populations of sagebrush
checkerspot butterflies in the Spring Mountains as a subspecies due to
the similarity of the characters he examined and compared between
sagebrush checkerspot butterflies and other checkerspot butterflies.
However, there are differences in the geographic distribution or
continuity and biological characteristics between the sagebrush
checkerspot butterfly population in the Spring Mountains and
populations elsewhere that support Austin's (1998, pp. 576-577)
designation of the Spring Mountains acastus checkerspot butterfly as a
subspecies.
Even though there is conflicting information on the taxonomic
designation of the Spring Mountains acastus checkerspot butterfly,
Austin (1998, p. 576) is cited as the reference for the subspecies
level taxonomic designation for the Spring Mountains acastus
checkerspot butterfly in the Integrated Taxonomic Information System
(ITIS). The ITIS is hosted by the United States Geological Survey
(USGS) Center for Biological Informatics (CBI) and is the result of a
partnership of Federal agencies formed to satisfy their mutual needs
for scientifically credible taxonomic information. ITIS recognizes the
Spring Mountains acastus checkerspot butterfly as a valid subspecies
(Retrieved June 18, 2012, from the Integrated Taxonomic Information
System on-line database, http://www.itis.gov). Based upon the best
available information, populations of sagebrush checkerspot butterflies
in the Spring Mountains are considered a valid subspecies and are,
thus, a valid taxonomic entity for consideration for listing under the
Act.
Distribution
The Spring Mountains acastus checkerspot butterfly is known only
from the Spring Mountains in Clark and Nye Counties, Nevada (Austin
1998, p. 577), at elevations ranging from minimums near 1,800 meters
(m) (5,900 feet (ft)) to maximums of 2,700 m (8,900 ft) (Weiss et al.
1997, p. 17). The majority of observations and habitat for the Spring
Mountains acastus checkerspot butterfly occur within the Spring
Mountains National Recreation Area (SMNRA), which is managed by the
U.S. Department of Agriculture's Forest Service (Forest Service),
Humboldt-Toiyabe National Forest. However, one colony occurs on private
property bordered by Forest Service-managed lands, and an incidental
observation at another location was documented on lands managed by the
U.S. Department of the Interior, Bureau of Land Management.
The Spring Mountains acastus checkerspot butterfly occurs
throughout the Spring Mountains and has been observed in 17 areas
(Table 1). However, the number of occupied areas reported in past
studies varies (12 occupied areas were reported in Boyd and Austin
1999, p. 20) based on how observations are spatially grouped. Four of
these areas (Trough Spring, Kyle Canyon, Griffith Peak Trail/Harris
Spring Road/Harris Mountain Road, and Potosi Mountain/Mt. Potosi/Boy
Scout Camp) are referred to interchangeably as colonies or population
sites (Boyd and Austin 1999, pp. 9, 20-21; Boyd and Austin 2002, pp. 5,
13; Boyd 2004, pp. 2-3). Colonies are isolated populations (Scott 1986,
p. 108) based on mate-locating behavior (Boyd and Austin 2002, p. 5;
Boyd 2009, p. 1) of one or more males observed over a period of time,
and they represent more than one incidental observation or sighting.
Researchers define colonies of Spring Mountains acastus checkerspot
butterflies based on the mate-locating behavior of males, also referred
to as mate-locating sites (Boyd and Austin 2002, p. 5; Boyd 2009, p.
1). Currently, only four colonies are known to exist. The remaining 13
areas are referred to as incidental observations or sighting areas
(Boyd and Austin 2001, p. 2; Boyd and Austin 2002, p. 3; Boyd 2004, p.
3), where intermittent observations of a few butterflies were recorded
at a location. Observations at incidental sighting areas, and the
potential for subsequent dispersal of individuals, may indicate the
presence of additional unknown colonies (Boyd and Austin 1999, pp. 60-
61; Boyd et al. 2000, p. 10). The areas where the Spring Mountains
acastus checkerspot butterfly has been observed in a colony or sighting
area represent the overall known population of the subspecies (Table
1).
Table 1--Areas Where Spring Mountains Acastus Checkerspot Butterfly
Observations Have Been Documented
[Areas ordered from north to south]
------------------------------------------------------------------------
Observation area First year observed
------------------------------------------------------------------------
Mt. Stirling........................... 1983.
Big Timber Spring...................... 1995 or before.
Wheeler Pass Road...................... 1987.
Trough Spring*......................... 2001.
McFarland Spring/Whisky Spring/Camp 2003.
Bonanza.
Willow Spring/Willow Creek............. 1979.
Clark Canyon........................... 1994.
Foxtail Canyon......................... 1998.
Deer Creek and picnic area............. 1965.
Deer Creek Road (Telephone Canyon side) 1981 or 1987.
Kyle Canyon--lower..................... 1996 or before.
Kyle Canyon--middle*................... 1950.
Kyle Canyon--upper..................... 1987.
Griffith Peak Trail/Harris Spring Road/ 1990.
Harris Mountain Road *.
Coal Spring............................ 1992.
Switchback Spring...................... 2003.
Potosi Mountain/Mt. Potosi/Boy Scout 1995.
Camp *.
------------------------------------------------------------------------
* Colony.
Sources: Weiss et al. 1995, pp. 4, 19; Weiss et al. 1997, pp. 6-7, 47;
Boyd and Austin 1999, pp. 19-21; Boyd 2004, pp. 2-3; Nevada Natural
Heritage Program 2009.
Status and Trends
Weiss et al. (1997, p. 2) indicated that butterfly populations are
highly dynamic, and butterfly distributions can be highly variable from
year to year. Butterflies may be restricted to moist and cool habitats
during dry, warm periods, potentially expanding their distribution
during periods marked by cooler and moister conditions (Weiss et al.
1997, pp. 2-3). Sagebrush checkerspot butterfly populations may undergo
extreme fluctuations as a result of rainfall, parasitism, and other
factors (Stout 2011, http://www.raisingbutterflies.org). Some
subspecies, such as the Spring Mountains acastus checkerspot butterfly,
may exist as a metapopulation (``local populations which interact via
individuals moving among populations'') (Hanski and Gilpin 1991, p. 7)
within the Spring Mountains (Weiss et al. 1997, p. 3). If this is the
case, maintenance of dispersal corridors and unoccupied habitats is an
important management consideration (Weiss et al. 1997, p. 3).
Determining the status of adults at a colony requires multiple
visits during appropriate flight conditions and frequently enough to
intercept a potentially short flight period. For example, in 1977,
Austin and Austin (1980, p. 40) reported visits to the same area of
Kyle Canyon in which the Spring Mountains acastus checkerspot butterfly
[[Page 59360]]
was observed on 2, 5, and 7 July, but not on 17 or 30 June and 15 July.
Thus, this flight period may have been less than 2 weeks. In contrast,
they reported that, in 1965, the flight period lasted over a 5-week
period. While these observations may indicate a variable flight period,
it is also possible that the perceived flight period may vary as a
result of a dynamic interrelationship between search effort and
abundance. In addition, assessments of population status and trends
based on counts of particular life stages may be complicated by
irregular life-history phenomena, such as an extended diapause (a
period of dormancy, commonly induced by seasonal change in photoperiod
(day length) or temperature) (Sands and New 2008, pp. 81-85).
Unnecessary conservation concerns may arise as a result of irregular
diapause that results in perceived changes in abundance (Sands and New
2008, pp. 81-85).
The largest known colony of Spring Mountains acastus checkerspot
butterfly occurs at Griffith Peak Trail/Harris Spring Road/Harris
Mountain Road. This was first documented as a sighting area in 1990,
and later described as a potential colony in 1999 (Boyd and Austin
1999, p. 20). The Trough Spring colony was first identified in 2001
(Boyd and Austin 2002, p. 5). Boyd (2004, p. 3) stated that a single
male observed at Willow Spring/Willow Creek in 2003 may have dispersed
from Trough Spring or another unknown colony, because there had been no
sightings in the area since the 1980s. The Spring Mountains acastus
checkerspot butterfly was first documented at Potosi Mountain/Mt.
Potosi/Boy Scout Camp in 1995 (Weiss et al. 1995, p. 6), and was
described as a colony for the first time in 2000 (Boyd et al. 2000, p.
4).
DataSmiths (2007, p. 17) concluded that absence of adults at a site
does not necessarily equate to ephemeral occupation or extirpation.
Observations of the Spring Mountains acastus checkerspot butterfly
illustrate this point. Boyd et al. (2000, p. 4) searched 17 areas (8
historical and 9 potential sites) for the Spring Mountains acastus
checkerspot butterfly in 1999. During the 1999 surveys, Spring
Mountains acastus checkerspot butterflies were observed at five of the
eight historical sites (including Kyle Canyon (middle) Colony Site),
with two of these described as potential new colonies (Griffith Peak
Trail/Harris Spring Road/Harris Mountain Road and Potosi Mountain/Mt.
Potosi/Boy Scout Camp). During 2003 surveys, the Spring Mountains
acastus checkerspot butterfly was observed again in the Willow Spring/
Willow Creek area (Boyd 2004, pp. 2-3) where it had not been seen
during surveys in 1999 (Boyd and Austin 1999, Table 7, p. 98).
Similarly, in 2003, the Spring Mountains acastus checkerspot butterfly
was observed in the McFarland Spring/Whisky Spring/Camp Bonanza area
(Boyd 2004, p. 2), even though it had not been observed there during
previous surveys in 1998 (Boyd and Austin 1999, Table 12). These
examples demonstrate that a lack of observations at a site does not
necessarily mean that a site is extirpated because adult surveys will
not detect diapausing larvae, and short adult flight periods coupled
with low numbers may drastically reduce the likelihood of observing
Spring Mountains acastus checkerspot butterflies.
Yearly population variation also is seen in the fluctuation in
numbers of Spring Mountains acastus checkerspot butterflies observed
during repeat surveys at the same locations (Table 2). Surveys from
2000 and 2001 at the Griffith Peak Trail/Harris Spring Road/Harris
Mountain Road site found that the highest total number of individuals
observed on a single day increased from 19 to 104. In 2003, the highest
number observed on a single day at the same site decreased to 27. In a
2006 interview with Bruce Boyd regarding observations that year, Boyd
reported that the Spring Mountains acastus checkerspot butterfly had
``done better'' than other endemic species and had ``good numbers'' at
Griffith Peak Trail/Harris Spring Road/Harris Mountain Road, as well as
at Potosi Mountain/Mt. Potosi/Boy Scout Camp (Boyd 2006, pers. comm.).
At locations where the butterfly was observed in 2006, Boyd stated that
it appeared to be in ``appropriate'' numbers (Boyd 2006, pers. comm.).
These observations support the conclusions of Weiss et al. (1997, p. 2)
of highly dynamic butterfly populations where sightings may occur
periodically throughout a species' range, and populations at colony
sites may fluctuate.
Table 2--Summary of Monitoring Results of Spring Mountains Acastus Checkerspot Butterfly at Three Colony Sites From 1998 Through 2011 Using Standardized
Survey Methods
--------------------------------------------------------------------------------------------------------------------------------------------------------
Year 1998 1999 2000 2001 2002 2003 2006 2007 2008 2010 2011
--------------------------------------------------------------------------------------------------------------------------------------------------------
Kyle Canyon (middle)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Highest /day................................ 4-10 5 6 8 6 7 4 1 4 ....... 1
Visits..................................... 16 11 9 6 4 4 1 6 8 ....... 6
Peak date(s)......................................... NR 6/19 6/15 & 6/18 6/24 6/10 6/21 6/13 & 6/24 ....... 6/13
6/30 6/21
--------------------------------------------------------------------------------------------------------------------------------------------------------
Griffith Peak Trail/Harris Spring Road/Harris Mountain Road
--------------------------------------------------------------------------------------------------------------------------------------------------------
Highest /day................................ ....... ....... 19 104 50 27 ....... ....... ....... 2* 5
Visits..................................... ....... ....... 9 5 5 4 ....... ....... ....... ....... 3
Peak date............................................ ....... ....... 6/11 6/18 6/20 6/29 ....... ....... ....... ....... 6/27 &
7/11
--------------------------------------------------------------------------------------------------------------------------------------------------------
Trough Spring
--------------------------------------------------------------------------------------------------------------------------------------------------------
Highest /day................................ ....... ....... ....... ....... 20 41 ....... ....... ....... ....... 1
Visits..................................... ....... ....... ....... ....... 3 5 ....... ....... ....... ....... 3
Peak date............................................ ....... ....... ....... ....... 6/18 6/1 ....... ....... ....... ....... 6/10
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sources: (Boyd and Austin 1999, Table 8; Boyd 2004, p. 8; Jones and Stokes 2007a, p. 4; Jones and Stokes 2007b, p. 3; Kingsley 2008, p. 3, Service
2011a, pp. 1-3, Thompson et al. 2012, Table 2).
NR = not reported.
* = did not use a standardized survey method.
[[Page 59361]]
Surveys were conducted in 2010 and 2011 for adult Spring Mountains
acastus checkerspot butterflies using both standardized and non-
standardized methods. In 2010, at the Griffith Peak Trail/Harris Spring
Road/Harris Mountain Road colony site, there were a total of four
butterflies observed during the season (two by Pinyon 2011, p. 19; and
two by Service 2011a, pp. 1-3), and the highest number of butterflies
observed on a single day was two (Service 2011a, pp. 1-3). Numbers
appeared to increase in 2011 at this colony site with a total of 86
reported observations (59 by Pinyon 2011, p. 19; 4 by Service 2011a,
pp. 1-3; 23 by Thompson et al. 2012, Table 2), and the highest number
of butterflies observed on a single day was 13 (Pinyon 2011, p. 19).
The 13 individuals observed by Pinyon in 2011 were not observed using a
standardized method similar to Pollard and Yates (1993 cited in Boyd
and Austin 1999, p. 33) and described by Boyd and Austin (1999, p. 33),
and are, therefore, not reported in Table 2. Results of the
standardized surveys performed by Thompson et al. (2012, Table 2) at
the other colony sites are shown in Table 2. Surveys for Spring
Mountains acastus checkerspot butterfly were planned for 2012; however
those data are not yet available.
Habitat
Sagebrush checkerspot butterfly habitat is described as dry washes
in sagebrush-juniper woodland, oak or mixed conifer woodland, and
streambeds (Opler 1999, p. 199). Elevations used by Spring Mountains
acastus checkerspot butterfly coincide with the intergraded upper
elevation of pi[ntilde]yon-juniper (Pinus monophylla-Juniperus
osteosperma) communities at 1,250-2,500 m (4,100-8,200 ft) and the
lower elevation white fir-ponderosa pine (Abies concolor-Pinus
ponderosa var. scopulorum) communities at 2,000-2,530 m (6,560-8,300
ft) (Niles and Leary 2007, pp. 5-6). Open vegetation communities
associated with previous fire disturbances appear to be the preferred
habitat (Boyd and Austin 2002, p. 5).
Biology
Adults
The flight season of the Spring Mountains acastus checkerspot
butterfly is between mid-May and mid-July (Austin and Austin 1980 p.
40; Weiss et al. 1997, pp. 6, 37; Austin 1998, p. 576; Boyd 2004, pp.
1-2), peaking near the later part of June (Weiss et al. 1997, pp. 6,
37; Boyd and Austin 1999, p. 20; Boyd and Austin 2002, p. 4; Boyd 2004,
p. 8). Distances moved during flight periods have not been documented,
although Schrier et al. (1976, p. 285) observed that the closely
related northern checkerspot butterfly could move as far as 1.6 km (1
mi). During the flight season, Spring Mountains acastus checkerspot
butterfly adults have been observed nectaring on Eriodictyon
angustifolium (yerba santa), Heliomeris multiflora var. nevadensis (=
Viguiera multiflora; Nevada golden-eye), Packera multilobata (= Senecio
multilobatus; lobeleaf groundsel), Ceanothus sp. (ceanothus), C.
greggii (Mojave ceanothus), Melilotus sp. (clover), Penstemon palmeri
(Palmer penstemon), and Apocynum sp. (dogbane) (Austin and Austin 1980,
p. 40; Weiss et al. 1995, p. 9; Boyd et al. 2000, p. 6; Jones & Stokes
2007a, p. 4; Thompson et al. 2012, p. 22).
Spring Mountains acastus checkerspot butterfly males may seek
females all day by perching and sometimes patrolling gulches (Scott
1986, p. 307; Kingsley 2008, pp. 7-8). Washes and linear features are
used primarily as mating sites during the flight season (Boyd and
Austin 2001, p. 6; Boyd and Austin 2002, p. 5). Males may perch on
several projecting objects in the same area, such as rocks or branches
(Scott 1986, pp. 46-47, 307; Kingsley 2008, pp. 4, 7-8). At these
sites, the males behave territorially. They remain in the same area and
pursue any other butterflies or insects that come within a zone of a
few square meters around the male, continuing this behavior towards the
intruding animal until it leaves (Boyd and Austin 2001, p. 5; Boyd and
Austin 2002, p. 5; Kingsley 2008, pp. 4, 7-8). During a brief flight
season (Weiss et al. 1997, pp. 6, 37), females remain at the site long
enough to find a male to mate with, and then leave the area to oviposit
(Boyd and Austin 2001, p. 6; Boyd and Austin 2002, p. 5). Mating has
been observed to last 40 minutes (Boyd 2004, p. 3). Sagebrush
checkerspot butterflies have a high mating success, as indicated by a
high percentage (>95) of females with spermatophores (a sac containing
sperm) (Shields 1967, pp. 90, 123; Rhainds 2010, pp. 212-213).
Approximately 10 days after mating, the female lays her eggs (Nunnallee
2011, p. 6).
Eggs
Clusters of sagebrush checkerspot butterfly eggs are laid on the
underside of host leaves and sometimes on flower buds (Scott 1986, p.
307; Stout 2011, http://www.raisingbutterflies.org). Sagebrush
checkerspot butterflies may lay 100 to 150 eggs in a cluster (Nunnallee
2011, p. 6). It may be advantageous for female butterflies to lay eggs
in clusters to reduce exposure to predation or if host plants are rare
or dispersed (Stamp 1980, p. 376). Eggs hatch after 6 days (Nunnallee
2011, p. 6), and the young larvae are gregarious on leaves or flowers
(Scott 1986, p. 307; Nunnallee 2011, p. 6).
Larvae
Gregarious pre-diapause larvae of sagebrush checkerspot butterflies
form silk webbing where they feed together on the larval host plant
(Nunnallee 2011, p. 6; Opler et al. 2011, http://www.butterfliesandmoths.org; Stout 2011, http://www.raisingbutterflies.org). It is hypothesized that gregarious larvae
may reduce rates of parasitism on the larvae because of collective
defenses and may also facilitate feeding on larval host plants,
particularly for early larvae, by enhancing the ability of larvae to
overcome plant defenses (Chew and Robbins 1984, p. 75). Chrysothamnus
viscidiflorus has been documented as a larval host plant (Boyd and
Austin 2002, p. 2; Austin and Leary 2008, p. 99), is a widely
distributed shrub in Western North America (Anderson 1986a, b as cited
in McArthur and Stevens 2004, p. 531; Stubbendieck 2003, p. 248), and
has a range that coincides with many of the ranges shown for sagebrush
checkerspot butterflies (Opler 1999, p. 199; Opler et al. 2011, http://www.butterfliesandmoths.org). Common names used interchangeably for
subspecies of C. viscidiflorus have included Douglas rabbitbrush,
chamisa, green rabbitbrush, low rabbitbrush, yellow rabbitbrush, viscid
rabbitbrush, sticky-leaved rabbitbrush, downy rabbitbrush, and narrow-
leaved rabbitbrush (Stubbendieck et al. 2003, p. 249; McArthur and
Stevens 2004, p. 532; Niles and Leary 2007, p. 19). Three subspecies of
C. viscidiflorus have been documented in the Spring Mountains,
including C. v. lanceolatus (variously known as viscid rabbitbrush,
sticky-leaved rabbitbrush, and yellow rabbitbrush), C. v. puberulus
(downy rabbitbrush), and C. v. viscidiflorus (known as viscid
rabbitbrush, sticky-leaved rabbitbrush, and narrow-leaved rabbitbrush)
(Niles and Leary 2007, p. 19). A common name for Chrysothamnus
viscidiflorus viscidiflorus has not been accepted (Young and Evans
1974, p. 469).
In the Spring Mountains, Niles and Leary (2007, p. 9) quantified
the abundance of the various subspecies of Chrysothamnus viscidiflorus
as rare, occasional, common, and abundant. Chrysothamnus viscidiflorus
ssp. lanceolatus is occasional to common on slopes, ridges, and in
washes (Niles and
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Leary 2007, p. 19). Chrysothamnus viscidiflorus ssp. puberulus (= var.
puberulus) is occasional to rocky washes and on slopes (Niles and Leary
2007, p. 19). Of butterfly host plants described by Weiss et al. (1997,
Figure 4), Chrysothamnus viscidiflorus is present in areas with low
tree canopy cover (mean of 17 percent). Chrysothamnus viscidiflorus
ssp. viscidiflorus (= var. viscidiflorus) is occasional to sandy-
gravelly washes (Niles and Leary 2007, p. 19). Chrysothamnus
viscidiflorus has many erect stems that are 1 to 3.5 ft (0.3 to 1.1 m)
tall, growing from a base (McArthur and Stevens 2004, p. 531). In the
Spring Mountains, C. viscidiflorus has been categorized as widespread,
with a large population, and is considered very robust to human
disturbance (Nachlinger and Reese 1996, pp. 66, 70). More recent
information indicates that the larval host plant is widely distributed,
but locally uncommon, within the Spring Mountains (D. Thompson 2012,
pers. comm.). It is unknown whether or not habitat is a limiting factor
for the subspecies.
It is unknown which of these subspecies of Chrysothamnus
viscidiflorus are used as a larval host plant by the Spring Mountains
acastus checkerspot butterfly; however, in maps prepared by Jones and
Stokes (2007b, Figure 5a), Spring Mountains acastus checkerspot
butterfly observations appeared to be more closely associated with C.
v. ssp. viscidiflorus than C. v. ssp. puberulus. Warren (2005, p. 232)
reported that all sagebrush checkerspot butterfly subspecies in Oregon
use C. v. ssp. viscidiflorus as a host plant, but that other subspecies
of C. viscidiflorus may be used as well. C. viscidiflorus is the most
commonly reported species of larval host plant for sagebrush
checkerspot butterfly subspecies, but other plant species have been
reported (Service 2011b, p. 4).
While not documented as a larval host plant for the Spring
Mountains acastus checkerspot butterfly, Machaeranthera canescens
occurs in similar habitats (Niles and Leary 2007, p. 20) used by the
Spring Mountains acastus checkerspot butterfly. Locations with reported
occurrences of M. canescens in the Kyle Canyon area (Jones and Stokes
2007b, Figure 13) are near Spring Mountains acastus checkerspot
butterfly observation areas (Jones and Stokes 2007b, Figure 5a).
Further study using appropriate methods (Shields et al. 1969, p. 24)
will be required to determine if Spring Mountains acastus checkerspot
butterfly uses other larval host plants.
Ericameria nauseosa (= Chrysothamnus nauseosus; rubber rabbitbrush)
also has been suspected of being a larval host plant of the Spring
Mountains acastus checkerspot butterfly (Weiss et al. 1997, p. 6). Boyd
and Austin (1999, pp. 20-21) unsuccessfully attempted to feed E.
nauseosa to Spring Mountains acastus checkerspot butterfly larvae, and
reported that their results were inconclusive. Early inferences that E.
nauseosa may be the larval host plant for the Spring Mountains acastus
checkerspot butterfly may be attributed to early uncertainty about its
taxonomy and its close resemblance to the northern checkerspot
butterfly, which has been documented to use E. nauseosa and C.
viscidiflorus as larval host plants (Scott 1986, p. 306; Austin and
Leary 2008, p. 102), and the interchangeable use of the generic common
name rabbitbrush when referring to rubber or green rabbitbrush. The
best available scientific and commercial information does not indicate
there is any use of E. nauseosa by sagebrush checkerspot butterflies
(Service 2011b, p. 4).
After feeding on the larval host plant during favorable conditions,
larvae enter diapause, which allows them to survive through the winter,
and which is likely a result of decreasing temperature and photoperiod
(Scott 1979, p. 172). Spring Mountains acastus checkerspot butterfly
larvae diapause under rocks as half-grown larvae during the winter
(Scott 1979, pp. 172, 191; Scott 1986, pp. 27, 307; Opler et al. 2011,
http://www.butterfliesandmoths.org). During times of unfavorable
weather, sagebrush checkerspot butterflies may diapause for many months
or years (Scott 1986, p. 307; Opler et al. 2011, http://www.butterfliesandmoths.org).
After winter, post-diapause larvae of other subspecies have been
reported to be solitary (Nunnallee 2011, p. 6); however, Spring
Mountains acastus checkerspot butterfly larvae of different instars
(larval stages of growth between molts of the exoskeleton (Scott 1986,
p. 21)) have been observed together in the Spring Mountains (Boyd 2004,
p. 3). When disturbed, larvae will release and fall to the understory,
where they roll into tight balls and are difficult to find (Wolfe 2004,
p. 13). Stamp (1984, p. 6) hypothesized that thrashing by checkerspot
butterflies after disturbance may be an adaptation to prevent
parasitization by wasps or flies. There are no known reports of
parasites or disease in populations of Spring Mountains acastus
checkerspot butterflies, likely because of limited numbers and past
research emphasis on adults, and because it is difficult to detect
parasites or disease in checkerspot and other butterflies. Parasites
documented to infect Neumoegen's checkerspot butterfly include the
Siphosturmia confusa fly (Stireman and Singer 2003, p. 630) and
braconid wasp Cotesia (= Apanteles) koebelei (Krombein et al. 1979, p.
249). It has been reported that for the subspecies acastus checkerspot
butterfly, populations fluctuate as a result of parasitism (Stout 2011,
http://www.raisingbutterflies.org). In fact, larval mortality in many
species of butterflies occurs as a result of predation (including
parasitism) and starvation (Haukioja 1993, as cited in Kuussaari et al.
2004, p. 148).
When enough suitable food is present, and after reaching an
adequate size, larvae find a pupation site where they attach themselves
to a silk mat (Scott 1986, p. 13) on a leaf or twig (Stout 2011, http://www.raisingbutterflies.org). In 2002, one of four larvae removed from
the population at the Griffith Peak Trail colony site successfully
pupated in 11 days (Boyd 2004, p. 3), while other subspecies are
reported to pupate in 18 days (Nunnallee 2011, p. 6). After pupation,
adult butterflies emerge to feed and seek mates.
Summary of Information Pertaining to the Five Factors
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR part 424) set forth 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.
In making this finding, information pertaining to the Spring
Mountains acastus checkerspot butterfly in relation to the five factors
provided in section 4(a)(1) of the Act is discussed below. In
considering what factors might constitute threats to a species, we must
look beyond the exposure of the species to a particular factor to
evaluate whether the species may respond to that factor in a way that
causes actual impacts to the species. If there is exposure to a
[[Page 59363]]
factor and the species responds negatively, the factor may be a threat
and, during the status review, we attempt to determine how significant
a threat it is. The threat is significant if it drives, or contributes
to, the risk of extinction of the species such that the species
warrants listing as endangered or threatened as those terms are defined
in the Act. However, the identification of factors that could impact a
species negatively may not be sufficient to compel a finding that the
species warrants listing. The information must include evidence
sufficient to suggest that these factors are operative threats that act
on the species to the point that the species may meet the definition of
an endangered or threatened species under the Act.
In making our 12-month finding on the petition we considered and
evaluated the best available scientific and commercial information.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
All Sites
Fire Suppression
The Spring Mountains acastus checkerspot butterfly may be
negatively affected by fire suppression as inferred by its proximity to
areas with fire disturbance (Boyd and Austin 2002, p. 5; Boyd 2004, p.
3-4). It has been speculated that effects to the Spring Mountains
acastus checkerspot butterfly may occur as a result of inhibited
dispersal (Boyd 2004, p. 3-4). One mechanism for the inhibited
dispersal could be a decrease in larval host plants across the
landscape caused by fire suppression. Chrysothamnus viscidiflorus
increases vigorously and rapidly at disturbed sites (Nachlinger and
Reese 1996, p. 32; McArthur and Stevens 2004, p. 532). After a
disturbance, such as a fire, C. viscidiflorus may dominate the habitat
for a long period of time (Young and Evans 1974, p. 469).
Fire suppression in the Spring Mountains has resulted in long-term
successional changes, including increased forest area and forest
structure (higher canopy cover, more young trees, and more trees that
are intolerant of fire) (Nachlinger and Reese 1996, p. 37; Amell 2006,
pp. 6-9; Boyd and Murphy 2008, pp. 22-28; Denton et al. 2008, p. 21,
Abella et al. 2011, pp.10, 12). Overall, we have limited information
about how the frequency, size, or severity of fire has changed through
time. However, the available evidence does not suggest that fire
suppression has reduced the amount of habitat for the species, is
likely to do so in the future, or that habitat is a limiting factor for
the Spring Mountains acastus checkerspot butterfly. Therefore, based on
the currently available information fire suppression is not currently a
threat to the subspecies, nor does it indicate that it is likely to
become so in the future.
Our review of the best available information indicates that habitat
modification or destruction associated with fire suppression is not a
threat to the subspecies, nor does the available information indicate
that it is likely to become so in the future. In addition, we discuss
the habitat threats at individual colony sites below.
Griffith Peak Trail/Harris Spring Road/Harris Mountain Road Colony Site
Aside from the limited information about the effects of fire
suppression on the Spring Mountains acastus checkerspot butterfly
rangewide, there is no information available to indicate that habitat
modification or destruction is a threat to the Griffith Peak Trail/
Harris Spring Road/Harris Mountain Road colony, nor does the available
information indicate that it is likely to become so in the future.
Kyle Canyon (Middle) Colony Site
Highway Modifications and Power Line Maintenance
Highway modifications and power line maintenance activities may
have affected the Spring Mountains acastus checkerspot butterfly in
areas near the Kyle Canyon (middle) colony site. Highway modifications
and power line maintenance (grading, sod dumping, large vehicle
occurrence (as indicated by tracks), and clearing) were observed in
1998 in the Kyle Canyon area (Boyd and Austin 1999, p. 59), and in
2006, historical grading, repairing and roadway replacement, and
illegal dumping also were observed near the Kyle Canyon (middle) colony
site (Jones and Stokes 2007a, Appendix B). However, these reports do
not provide information or references that characterize the scope,
immediacy, and intensity of any of these potential stressors (processes
or events with negative impacts). While the reports indicate that these
activities took place in the same area where Spring Mountains acastus
checkerspot butterfly occurs, there is no available information
indicating the level of exposure, such as whether larval and nectar
plants were impacted. The site was inventoried 16 times in 1998, and,
based on the descriptions provided in the report (Boyd and Austin 1999,
p. 10) and the absence of any further disturbance documented in
subsequent surveys (11 visits in 1999, 9 visits in 2000, 7 visits in
2001, 6 in 2002, and 5 in 2003) (Boyd et al. 2000, pp. 1-36; Boyd and
Austin 2001, pp. 1-38; Boyd and Austin 2002, pp. 1-30; Boyd 2004, pp.
1-11), it appears that these activities may be localized and
infrequent. In addition, an increase in the number of individuals
observed from 1999 to 2001 at the Kyle Canyon (middle) colony site
(Table 2) after the highway modifications and power line maintenance
suggests that these activities did not cause sufficient impacts to
cause a decline at this colony site. No information is available
regarding highway modifications and power line maintenance at the Kyle
Canyon (middle) Colony Site after 2006.
Highway modifications and power line maintenance activities have
occurred historically in localized areas. Although we are not aware of
any further highway modification projects, we understand that
maintenance activities can take place in the future, know of no planned
specific action. The information suggests that currently the intensity
of this stressor is low and the exposure to the Spring Mountains
acastus checkerspot butterfly is insignificant because these activities
occur infrequently in small areas within the butterfly's range.
Therefore, we have determined that highway modifications and power line
maintenance are not threats to the Spring Mountains acastus checkerspot
butterfly now, nor does the available information indicate that they
are likely to become so in the future.
Fuel Treatments
Fuel reduction projects may affect the Spring Mountains acastus
checkerspot butterfly negatively or beneficially. The effects of fuel
reduction treatments on butterflies depend upon the timing (Pilliod et
al. 2006, p. 23). Fuel reduction projects could affect the Spring
Mountains acastus checkerspot butterfly negatively by reducing the
quantity or quality of habitat and affecting survival or fecundity. On
the other hand, fuel reduction projects could beneficially affect the
Spring Mountains acastus checkerspot butterfly by creating conditions
that favor nectar and larval host plants (Weiss et al. 1997, p. 27). As
mentioned above, Chrysothamnus viscidiflorus increases vigorously and
rapidly at disturbed sites (McArthur and Stevens 2004, p. 532) and may
dominate the habitat for a long period of time following disturbance
(Young and Evans 1974, p. 469).
The U.S. Forest Service implemented the Spring Mountains Hazardous
Fuels Reduction Project in the Spring
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Mountains between 2008 and 2011 (Lillis 2010). It was designed to
reduce the volume and cover of woody vegetation to lower the wildfire
risk to life and property in the SMNRA wildland-urban interface (Forest
Service 2007a, pp. 1-18; Forest Service 2007b, pp. 1-57). Design
criteria were developed to reduce or avoid potential resource
conflicts, including those associated with the Spring Mountains acastus
checkerspot butterfly (Forest Service 2007a, p. 4).
In areas where the Spring Mountains Hazardous Fuels Reduction
Project coincides with the Spring Mountains acastus checkerspot
butterfly, the likelihood of direct mortality to the butterfly or
impacts to its habitat were minimized by implementing the design
criteria in the project's environmental assessment (Forest Service
2007b, Appendix B, Design Criteria B1, B6, W5, W6, W7, W11, M1). The
design criteria provided for surveys of butterflies and habitat,
habitat mapping, restrictions on host plant removal in core colonies,
avoidance of host plants, minimization of disturbance by using manual
methods, weed prevention, education of implementation crews, monitoring
during implementation, and post-project monitoring of butterflies and
their habitat. The scope or geographic extent of the Spring Mountains
Hazardous Fuels Reduction Project is localized because it occurs along
the wildland-urban interface in one colony site area, Kyle Canyon
(middle). The project's initial entry has already occurred, but re-
treating of shrubs may occur every 5 to 10 years after the initial
treatment (Forest Service 2007a, p. 3).
The level of exposure to the Spring Mountains acastus checkerspot
butterfly's eggs and larvae from the Spring Mountains Hazardous Fuels
Reduction Project is low to insignificant because of the project design
criteria and the short time required for eggs to hatch. Exposure of
active larvae to impacts from fuel reduction projects would be small to
insignificant when design criteria are planned and implemented, such as
avoiding larval host plants and ensuring that the method (for example,
manual versus mechanical) and timing (periods of larval inactivity) of
treatment result in larvae having a lower likelihood of exposure.
Impacts to Spring Mountains acastus checkerspot butterfly pupae are
likely insignificant because they affix to the underside of leaves for
a short period in this stage, and are provided some protection by their
larval host plant. Finally, Spring Mountains acastus checkerspot
butterfly adults are mobile and may escape threats from fuels reduction
projects. Effects on breeding adult Spring Mountains acastus
checkerspot butterflies are likely insignificant because a short time
is required for successful copulation and the duration of fuel
treatment activities is likely brief. The Forest Service avoids
treatment of vegetation along dry washes (Forest Service 2007a, W8),
which also reduces the likelihood of exposure and impacts to breeding
Spring Mountains acastus checkerspot butterflies.
Although the Spring Mountains Hazardous Fuels Reduction Project may
result in short-term negative impacts to the Spring Mountains acastus
checkerspot butterfly, the best available information does not indicate
that this project has affected the Spring Mountains acastus checkerspot
butterfly negatively at the population level now, nor is it likely to
in the future.
Middle Kyle Complex Project
The Forest Service purchased a golf course property in 2004 that
will be used for the Middle Kyle Complex Project (Forest Service 2009,
pp. 2-4). The project includes construction of a visitor center and
associated trail, and design criteria are in place to prevent and
minimize impacts to the Spring Mountains acastus checkerspot butterfly
(Forest Service 2009, pp. 4-5). This design includes criteria and
measures that will avoid and minimize temporary construction
disturbance to known Spring Mountains acastus checkerspot butterfly
breeding areas. The design criteria include the following: Prohibit
construction of Kyle Canyon Wash Trail and bury utilities from early
May to mid-July (to avoid the butterfly's flight season); erect
temporary construction fencing along the proposed construction limits
prior to any ground-disturbing activities; contain all activities
within the approved construction limits; maintain temporary fencing
until notified by the contracting officer; collect native seed from
appropriate larval host and nectar plants; revegetate temporary
disturbance areas following completion of construction; implement
construction dust control measures to minimize impacts to blooming
nectar plant populations; reduce off-trail use in documented Spring
Mountains acastus checkerspot butterfly breeding and mate selection
areas; and construct a fence or barrier adjacent to the newly
constructed trail in Kyle Canyon Wash. When the project is implemented,
in 2012 or later, the design criteria and measures should result in
minimizing impacts to the Spring Mountains acastus checkerspot
butterfly and its habitat in Kyle Canyon Wash. Any negative impacts
from the project are anticipated to be minor and have negligible
impacts to the overall population of the subspecies and habitat at this
site.
The Middle Kyle Complex Project will occur in a localized area,
and, because of the design criteria, including avoidance of larval host
plants, the project will result in low response, low intensity, and
ultimately insignificant exposure of Spring Mountains acastus
checkerspot butterflies to impacts. Therefore, we have determined that
the Middle Kyle Complex Project is not a threat to the Spring Mountains
acastus checkerspot butterfly now, nor does the available information
indicate that it is likely to become one in the future.
Potosi Mountain/Mt. Potosi/Boy Scout Camp Colony Site
Fuel Treatments
The Potosi Mountain/Mt. Potosi/Boy Scout Camp colony site is
located at the Boy Scouts of America Kimball Scout Reservation, north
of Potosi Mountain. A fuels reduction project, funded through a grant
from the Nevada Division of Forestry, was implemented in April 2007
(Otero 2007, p. 6). The 2007 fuels reduction project resulted in cut
wood waste stacked more than a meter high along and on both sides of
the dirt road at this site, and it was asserted that the cut waste
effectively blocked all male perching and mate-locating sites in June
that year (Boyd 2009, p. 3). We interpret the term ``blocked'' to mean
obstruction of male perching and mate-locating sites as a result of
these areas being covered by debris. The best available information
does not indicate that the larval host plant for the Spring Mountains
acastus checkerspot butterfly occurred abundantly near the road at this
colony site. Chrysothamnus viscidiflorus was not observed in this area
after searching the sides of the canyon (Thompson et al. 2012, p. 24)
where Spring Mountains acastus checkerspot butterflies have been
historically observed (Weiss et al. 1997, p. 6). However, Spring
Mountains acastus checkerspot butterflies may be using adjacent areas
that contain the larval host plant and areas near the road for mate
locating. Our analysis addresses the alleged impact caused by blocking
male perching and mate-locating sites.
The best available information does not indicate if, or to what
extent, the alleged blocking of male perching sites had occurred at
this site. The Potosi Mountain/Mt. Potosi/Boy Scout Camp colony site
was visited two times in 2011, and waste piles were no longer present
(Service 2011a, pp. 1-3).
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However, wood chips were present near the road and camping areas, but
had mostly decomposed, with some patches remaining (Service 2011a, pp.
1-3). Fuel reduction projects likely will reoccur in the future as part
of wildland-urban interface projects to prevent damage to life or
property from wildfire; however, the available information does not
indicate that fuel reduction is impacting the subspecies such that it
is currently affected at the population level, nor does it indicate
that it is likely to in the future.
The best available information indicates that the fuels reduction
project at the Boy Scouts of America Kimball Scout Reservation, north
of Potosi Mountain, occurred in April before breeding activity
occurred, and, thus, breeding adults likely were not disturbed.
Although the number of sites available for perching by males may be
reduced temporarily if cut waste is piled for later treatment (commonly
chipping or burning), other sites along the road and in the canyon
would be available within this site. The Spring Mountains acastus
checkerspot butterfly has been observed using multiple perch sites
during mate-locating (Kingsley 2008, pp. 4, 7-8). Because breeding
occurs during a brief time period, the butterflies use multiple perch
sites, and they likely exhibit a high breeding success rate (Shields
1967, p. 123; Rhainds 2010, pp. 212-213), impacts to the Spring
Mountains acastus butterfly from the fuels reduction project at Potosi
Mountain/Mt. Potosi/Boy Scout Camp colony site were likely minimal and
insignificant.
The fuels reduction project at the Potosi Mountain/Mt. Potosi/Boy
Scout Camp colony site is localized and will likely occur again in the
future because maintenance will be required and fires are being
suppressed. The intensity and exposure of the impact from stacking cut
waste to the Spring Mountains acastus checkerspot butterfly is low and
insignificant because the best available information indicates that
Spring Mountains acastus checkerspot butterflies are able to use more
than one perching site and that they can successfully breed in only a
short period of time. We have determined that the stacking of cut waste
at the Potosi Mountain/Mt. Potosi/Boy Scout Camp colony site is not a
threat to the Spring Mountains acastus checkerspot butterfly now, nor
does the available information indicate that it is likely to become a
threat in the future.
Trough Spring Colony Site
Off-Highway Vehicles
Information in our files indicates that off-highway vehicles have
been present at the Trough Spring colony site (Service 2011a, pp. 1-3).
Off-highway vehicles could adversely affect the Spring Mountains
acastus checkerspot butterfly by reducing the quantity or quality of
habitat, reducing survival or fecundity, or directly impacting
individuals. Off-highway vehicles were observed on the road that goes
to Trough Spring during the 2011 field season, but no off-highway
vehicles or signs of vehicle use were observed in Spring Mountains
acastus checkerspot butterfly habitat with its larval host plant
present (Service 2011a, pp. 1-3). Any vehicle access from the end of
the road to Trough Spring and Spring Mountains acastus checkerspot
butterfly habitat is inhibited by tree downfall and dense shrubs
resulting from a wildfire (Service 2011a, pp. 1-3). In addition, the
Trough Spring colony site is partially within the Mt. Charleston
Wilderness, where motor vehicle use is prohibited.
The best available information suggests that the Spring Mountains
acastus checkerspot butterfly is not being affected by off-highway
vehicles. Although off-highway vehicles will likely continue to use the
road that goes to Trough Spring in the future, the best available
information indicates that off-highway vehicles have impacted the
habitat and the Spring Mountains acastus checkerspot butterfly.
However, the exposure of the Spring Mountains acastus checkerspot
butterfly to impacts from off-highway vehicles is insignificant because
of obstructions described above between the designated road and the
Trough Spring colony site area. We have determined that off-highway
vehicle use does not pose a threat to the Spring Mountains acastus
checkerspot butterfly at the Trough Spring colony site now, nor does
the available information indicate that it is likely to become one in
the future.
Horses and Elk
Horses (Equus ferus) and elk (Cervus elaphus) utilize the Trough
Spring area (Service 2011a, pp. 1-3; Thompson et al. 2012, p. 22).
Horses and elk could affect Spring Mountains acastus checkerspot
butterflies by trampling them when moving through or by feeding in
areas occupied by all life stages. While horses or elk could cause
direct mortality, the likelihood of this occurring is probably low
because: (1) Horses feed predominantly on forbs or grasses (National
Research Council 1982, pp. 26, 31); (2) elk that may be more likely to
feed on Chrysothamnus viscidiflorus are more likely to do so in the
winter (Stubbendieck et al. 2003, p. 249), when larvae are in diapause
below rocks (Scott 1979, pp. 172, 191; Scott 1986, pp. 27, 307; Opler
et al. 2011, http://www.butterfliesandmoths.org); (3) eggs or pupae are
exposed for only a brief period of time in late spring or early summer
(1 to 3 weeks) (Nunnallee 2011, p. 6; Boyd 2004, p. 3); and (4) if
larvae are disturbed, they may fall (Wolfe 2004, p. 13) to the ground
beneath the plant where trampling and feeding may be inhibited by
thicker shrub branches.
Overall, the quantity or quality of larval or nectar plant habitat
for the Spring Mountains acastus checkerspot butterfly may be affected
by ungulate browsing. Food for Spring Mountains acastus checkerspot
butterfly larvae may increase under certain browsing regimes. In
experimental tests on the effects of clipping Chrysothamnus
viscidiflorus, herbage production was increased when the plants were
partially defoliated (Willard and McKell 1978, p. 515). Moderate and
heavy clipping intensities resulted in reduced herbage production
compared to unclipped C. viscidiflorus shrubs. Based upon these
results, light defoliation may result in greater herbage production
than moderate, heavy, and no defoliation. Wild and domestic animals do
not prefer most subspecies of C. viscidiflorus (Young and Evans 1974,
p. 469). While horses are considered grazers, they have been observed
to feed on C. viscidiflorus in the summer (Smith et al., as cited in
National Research Council 1982, p. 31). During visits to the site in
2011, browsing at the Trough Spring colony site appeared to be heavy
(Service 2011a, pp. 1-3). Grazing of grasses or forbs can decrease
competition for C. viscidiflorus. Subspecies of C. viscidiflorus have
been observed to vary in palatability to ungulates (McArthur and
Stevens 2004, p. 532). In the late fall and winter, after more
desirable forage has been consumed, C. viscidiflorus may be an
important source of food for game and livestock (McArthur and Stevens
2004, p. 532).
Grazing and browsing by horses and elk are localized at the Trough
Spring colony site, and these activities are expected to continue into
the future. Because Chrysothamnus viscidiflorus plants are not removed
and Spring Mountains acastus checkerspot butterfly larvae are able to
evade browsing animals by falling to the ground when disturbed (Wolfe
2004, p. 13), the impact of grazing and browsing is likely
[[Page 59366]]
low. If grazing and browsing intensity is moderate to high, however,
this may result in direct mortality of individuals or a reduction in
available host plants. The available information does not indicate that
browsing is negatively impacting the Spring Mountains acastus butterfly
at the population level; therefore, the best available scientific and
commercial information does not indicate that ungulates are currently a
threat to the subspecies, nor are they likely to become so in the
future.
All Sites
Conservation Efforts to Reduce Habitat Destruction, Modification, or
Curtailment of Its Range
The Spring Mountains acastus checkerspot butterfly is listed in the
SMNRA Conservation Agreement (Forest Service et al. 1998, p. 32) and is
considered under a 2004 voluntary memorandum of agreement (MOA) between
the Forest Service and the Service (Forest Service and Fish and
Wildlife Service 2004, p. 1). The MOA was designed to establish a
general framework for a streamlined process for interagency cooperation
between the Humboldt-Toiyabe National Forest and the Service (Forest
Service and Fish and Wildlife Service 2004, p. 1). The conservation
agreement was in effect from April 13, 1998, to 2008 (Forest Service et
al. 1998, pp. 44, 49), when it was renewed (Forest Service 2008). The
conservation agreement is still being implemented. A new conservation
agreement is currently being developed for the SMNRA. The conservation
agreement, MOA, and Clark County Multiple Species Habitat Conservation
Plan (MSHCP) guide and assist agency planning for Spring Mountains
acastus checkerspot butterfly habitat and population monitoring. The
conservation agreement and MOA facilitate protection-oriented resource
management that considers conservation values through early project
planning, as well as species, habitat, and ecosystem inventory,
protection, monitoring, restoration, research, and education (Forest
Service et al. 1998, p. 1), which may help alleviate negative impacts
to the butterfly. Voluntary conservation actions from the conservation
agreement (Forest Service et al. 1998, pp. 1-50) are also found in the
MSHCP (RECON 2000c pp. A-79-A-88).
Summary of Factor A
We do not find highway modification and power line maintenance,
hazardous fuels reduction projects, equestrian traffic, off-highway
vehicle use, and browsing by horses or elk to be threats to the Spring
Mountains acastus checkerspot butterfly. Although fire suppression has
been suggested to negatively impact Spring Mountains acastus
checkerspot butterfly habitat, the available information does not
suggest that changes to fire frequency or changes in habitat quality or
quantity such that fire suppression is currently a threat to the
subspecies or likely to become one in the future. In addition, the
available information does not indicate that habitat is a limiting
factor for the Spring Mountains acastus checkerspot butterfly now or
likely to become so in the future. Based upon our review of the best
available scientific and commercial information, we find that the
present or threatened destruction, modification, or curtailment of its
habitat or range is not a threat to the Spring Mountains acastus
checkerspot butterfly, nor is it likely to become so in the future.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
In areas surrounding the range of the Spring Mountains acastus
checkerspot butterfly, sagebrush checkerspot butterflies have been
confiscated from illegal commercial traders (U.S. Attorney's Office
1994, pp. 23, 47; Alexander 1996, pp. 1-6). One sagebrush checkerspot
was removed from the Grand Canyon National Park in 1985, and 14 were
removed from Death Valley National Park in 1987 (U.S. Attorney's Office
1994, pp. 23 and 47), but it is unknown whether any sagebrush
checkerspot butterflies have been collected for unauthorized commercial
use in the Spring Mountains. The Spring Mountains are located between
Grand Canyon National Park to the east (approximately 300 km (180 mi))
and Death Valley National Park to the west (approximately 130 km (80
mi)). There is no available information regarding the utilization of
Spring Mountains acastus checkerspot butterflies for unauthorized
commercial purposes.
Spring Mountains acastus checkerspot butterflies have been
collected for authorized commercial use, including for scientific and
educational purposes. We infer that the earliest collections of Spring
Mountains acastus checkerspot butterflies are from the 1920s, based on
Boyd and Austin (1999, p.19). Most documented collections of Spring
Mountains acastus checkerspot butterfly have occurred for scientific or
educational purposes (Table 3). On Forest Service-administered lands, a
special use permit is required for the commercial collection of
butterflies (36 CFR 251.50), which would include collections for
research, museums, universities, or professional societies (Forest
Service 2003, pp. 2-3).
Table 3--Numbers of Spring Mountains Acastus Checkerspot Butterfly Specimens Collected by Area, Year, and Sex
Found in Published Documents
----------------------------------------------------------------------------------------------------------------
Collection area/year Male Female Unknown Total
----------------------------------------------------------------------------------------------------------------
Deer Cr. Rd.
1950........................................ .............. .............. 1 1
1965........................................ 1 .............. .............. 1
1977........................................ 6 2 .............. 8
1981........................................ .............. 3 .............. 3
---------------------------------------------------------------
Deer Cr. Rd. Total...................... 7 5 1 13
Spring Mountains (general reference)
1934........................................ 10 1 .............. 11
2002........................................ .............. .............. 2 2
Harris Spring Rd./Harris Mountain Rd.
1990........................................ 16 6 .............. 22
1999........................................ 2 2 .............. 4
Griffith Peak Trail
2002........................................ .............. .............. 4\L\ 4
[[Page 59367]]
Kyle Canyon
1950........................................ .............. .............. 2 2
1965........................................ 2 .............. 62 64
1974........................................ 1 2 .............. 3
1977........................................ 15 2 .............. 17
1978........................................ 6 1 .............. 7
1979........................................ 41 3 .............. 44
1981........................................ 8 1 .............. 9
1987........................................ 17 5 .............. 22
1988........................................ 5 .............. .............. 5
1989........................................ 28 5 .............. 33
1990........................................ 13 2 .............. 15
2006........................................ .............. .............. 2 2
---------------------------------------------------------------
Kyle Canyon Total....................... 136 21 66 223
Willow-Cold Creek
1979........................................ 1 .............. .............. 1
---------------------------------------------------------------
Area Totals............................. 172 35 73 ..............
---------------------------------------------------------------
Total............................... .............. .............. .............. 280
----------------------------------------------------------------------------------------------------------------
References: Austin and Austin 1980, p. 40; Austin 1998, p. 576; Boyd 2004, p. 3; Boyd et al. 2000, p. 7; Jones
and Stokes 2007a, Service 2012, pp. 1-4, and YPM ENT Catalog (http://peabody.yale.edu/collections/search-collections?ent) Note: duplicate specimens from Austin and Austin 1980 and Austin 1998 have been accounted
for.
\L\ = larvae
Prior to 2006, collecting for noncommercial (recreational and
personal) purposes did not require a collecting permit issued by the
Regional Forester in most areas (Forest Service 1998, p. 1; Joslin
1998, p. 74). Since 1996 within the SMNRA, Lee Canyon, Cold Creek,
Willow Creek, and upper Kyle Canyon have been identified as areas where
permits are required for any butterfly collecting (Forest Service 1996,
pp. 28, E9). There are no records indicating that special use permits
have been issued for commercial or noncommercial collecting of Spring
Mountains acastus checkerspot butterflies in the Spring Mountains (S.
Hinman 2011, pers. comm.). However, there are published and unpublished
documented accounts of collections from the Spring Mountains (Austin
and Austin 1980, p. 40; Austin 1998, p. 576; Boyd 2004, p. 3; Jones and
Stokes 2007a, Table 5; Service 2012, pp. 1-4; YPM ENT Catalog, http://peabody.yale.edu/collections/search-collections?ent) (see Table 3 for
references).
The best available information indicates that Spring Mountains
acastus checkerspot butterflies have been collected for personal use
(Service 2012, pp. 1-4). In some cases, private collectors have more
extensive collections of particular species than museums (Alexander
1996, p. 2). Published and unpublished accounts of Spring Mountains
acastus checkerspot butterfly specimens in collections vary, with
typically more males collected than females during any year (Table 3).
Documented specimens indicate that most collections are from the Kyle
Canyon area. A survey of butterfly collectors in The Lepidopterists'
Society in the Northwest showed that approximately one-third of the
respondents indicated that they collected for personal collections,
another third collected for research or museum collections, and the
remainder fell within categories that may count for either (Mazzei and
Shapiro 2001, p. 103).
The collection of butterflies in general results in the direct
mortality of individuals and, when a population is small, may affect
the population's ability to recover. Butterfly collecting is generally
thought to have less of an impact on butterfly populations compared to
other threats; however, populations already stressed by other factors
may be threatened by intensive collecting (Thomas 1984, p. 345; Miller
1994, pp. 76, 83; New et al. 1995, p. 62). Thomas 1984 (p. 345)
suggested that closed, sedentary populations of fewer than 250 adults
are most likely to be at risk from overcollection. While there is
little documentation of the extirpation of any butterfly species as a
result of overcollecting (Miller 1994, p. 76), it has been shown that
removing a large number of female specimens from a population may
result in a greater threat of population decline (Hayes 1981, p. 197)
and potentially hasten the extinction of a species (Thomas 1984, p.
341).
The reported observed or captured sex ratio (males:females) in
Spring Mountains acastus checkerspot butterflies is strongly biased
(170:33) towards males (Table 3). Although many factors can affect the
differences between the observed and actual sex ratios, which vary
between years (Ehrlich et al. 1984, pp. 527-539; Boggs and Nieminen
2004, pp. 92-94), the magnitude of this difference suggests that this
bias is real, and that there are typically fewer females than males in
Spring Mountains acastus checkerspot butterfly populations. Because
males and females are similar in appearance, it may be difficult for
most collectors to selectively capture either sex.
There is no available information regarding the utilization of
Spring Mountains acastus checkerspot butterflies for commercial
purposes (other than for scientific and educational purposes) in the
past, or information to indicate a historic, current, or future demand.
The Spring Mountains acastus checkerspot butterfly has been collected
historically for recreational, scientific, and educational purposes.
Published accounts of collections for management or scientific purposes
indicate that collecting Spring Mountains acastus checkerspot
butterflies has become less frequent in the last couple of decades
(Table 3).
[[Page 59368]]
Summary of Factor B
Survey data indicate abundances may be low, but we do not know
actual population numbers of the Spring Mountains acastus checkerspot
butterfly. Therefore, the percentage of the population of Spring
Mountains acastus checkerspot butterfly that has been removed through
collecting is unknown. However, the number of reported Spring Mountains
acastus checkerspot butterflies collected has declined in recent
decades, and the available information does not indicate that
collection has had an adverse effect on the species, or nor is it
likely to have an adverse effect in the future. Nonetheless, because
collection is known to occur, we will work with the Forest Service to
enhance the effectiveness of their permitting program and continue to
monitor abundance and collection efforts. Based upon our review of the
best available scientific and commercial information, we find that
overutilization for commercial, recreational, scientific or educational
purposes is not a threat to the Spring Mountains acastus checkerspot
butterfly now, nor is it likely to become so in the future.
Factor C. Disease or Predation
There is no available information regarding any impacts from either
disease or predation on the Spring Mountains acastus checkerspot
butterfly. Therefore, based on the best available scientific and
commercial information, we do not find disease or predation to be
threats to the Spring Mountains acastus checkerspot butterfly now, nor
are they likely to become so in the future.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Existing regulatory mechanisms or other agreements that could
provide some protection for the Spring Mountains acastus checkerspot
butterfly include: (1) Local land use laws, processes, and ordinances;
(2) State laws and regulations; and (3) Federal laws and regulations.
Actions adopted by local groups, States, or Federal entities that are
discretionary, including conservation strategies and guidance, are not
regulatory mechanisms; however, we will discuss and evaluate them
below. The Spring Mountains acastus checkerspot butterfly primarily
occurs on Federal land under the jurisdiction of the Forest Service;
therefore, our discussion will primarily focus on Federal laws.
Local Laws and Ordinances
There is no available information regarding local land use laws and
ordinances that have been issued by Clark County or other local
government entities for protection of the Spring Mountains acastus
checkerspot butterfly.
State Law
Nevada Revised Statute sections 503 and 527 offer protective
measures to wildlife and plants, but do not include invertebrate
species such as the Spring Mountains acastus checkerspot butterfly.
Therefore, no regulatory protection is offered under Nevada State law.
Federal Law
Spring Mountains acastus checkerspot butterflies have been detected
consistently in four known colony sites in recent years. Three of the
colony sites, Griffith Peak Trail/Harris Spring Road/Harris Mountain
Road, Kyle Canyon (middle), and Trough Spring, are located mainly on
Federal land. Large portions of the Griffith Peak Trail and Trough
Spring colony sites are located within the Mt. Charleston Wilderness.
The Forest Service manages lands designated as wilderness under the
Wilderness Act of 1964 (16 U.S.C. 1131-1136). Within these areas, the
Wilderness Act states the following: (1) New or temporary roads cannot
be built; (2) there can be no use of motor vehicles, motorized
equipment, or motorboats; (3) there can be no landing of aircraft; (4)
there can be no other form of mechanical transport; and (5) no
structure or installation may be built. As such, the majority of Spring
Mountains acastus checkerspot butterfly habitat in the Griffith Peak
Trail and Trough Springs area is protected from direct loss and
degradation by the prohibitions of the Wilderness Act. Spring Mountains
acastus checkerspot butterfly habitat at Kyle Canyon, Potosi Mountain,
along the Harris Spring and Harris Mountains Road, and elsewhere is
located outside of the Mt. Charleston Wilderness, and, thus, it is not
subject to protections afforded by the Wilderness Act.
The National Environmental Policy Act of 1969, as amended (NEPA)
(42 U.S.C. 4321 et seq.), requires Federal agencies, such as the Forest
Service, to describe proposed agency actions, consider alternatives,
identify and disclose potential environmental impacts of each
alternative, and involve the public in the decision-making process.
Federal agencies are not required to select the NEPA alternative having
the least significant environmental impacts. A Federal agency may
select an action that will adversely affect sensitive species, provided
that these effects are identified in a NEPA document. NEPA itself is a
disclosure law, and does not require subsequent minimization or
mitigation of actions taken by Federal agencies. Although Federal
agencies may include conservation measures for the Spring Mountains
acastus checkerspot butterfly as a result of the NEPA process, such
measures are not required by the statute. The Forest Service is
required to analyze its projects in accordance with NEPA.
The SMNRA is 1 of 10 districts of the Humboldt-Toiyabe National
Forest. Public Law 103-63, dated August 4, 1993 (the Spring Mountains
National Recreation Area Act, 16 U.S.C. 460hhh et seq.), established
the SMNRA to include approximately 316,000 acres (128,000 hectares) of
Federal lands managed by the Forest Service in Clark and Nye Counties,
Nevada, for the following purposes:
(1) To preserve the scenic, scientific, historic, cultural,
natural, wilderness, watershed, riparian, wildlife, threatened and
endangered species, and other values contributing to public enjoyment
and biological diversity in the Spring Mountains of Nevada;
(2) To ensure appropriate conservation and management of natural
and recreation resources in the Spring Mountains; and
(3) To provide for the development of public recreation
opportunities in the Spring Mountains for the enjoyment of present and
future generations.
The National Forest Management Act of 1976, as amended (NFMA) (16
U.S.C. 1600 et seq.), provides the principal guidance for the
management of activities on lands under Forest Service jurisdiction
through associated land and resource management plans for each forest
unit. Under NFMA and other Federal laws, the Forest Service has the
authority to regulate recreation, vehicle travel, and other human
disturbance; livestock grazing; fire management; energy development;
and mining on lands within its jurisdiction. Current guidance for the
management of Forest Service lands in the SMNRA is under the Toiyabe
National Forest Land and Resource Management Plan and the SMNRA General
Management Plan. In June 2006, the Forest Service added the Spring
Mountains acastus checkerspot butterfly and three other endemic
butterflies to the Regional Forester's Sensitive Species List in
accordance with Forest Service Manual 2670. The Forest Service's
objective in managing
[[Page 59369]]
sensitive species is to prevent listing of species under the Act,
maintain viable populations of native species, and develop and
implement management objectives for populations and habitat of
sensitive species. Projects listed under Factor A above for the Kyle
Canyon (middle) colony site have been guided by these Forest Service
plans, policies, and guidance. However, removal or degradation of
butterfly habitat has occurred as a result of projects approved by the
Forest Service in Kyle Canyon.
Because the Spring Mountains acastus checkerspot butterfly is
designated a sensitive species, Standard 0.28 of the Land and Resource
Management Plan for the Spring Mountains requires a collecting permit
issued by the Regional Forester (except for traditional use by American
Indians) (Forest Service 1996, p. 18). Furthermore, Standard 11.6
indicates that collecting, regardless of species, in specific areas
including Cold Creek, Lee Canyon, upper Kyle Canyon, and Willow Creek
also requires a permit (Forest Service 1996, p. 31). These items,
identified as ``standards,'' are constraints or mitigation measures
that must be followed as directed by the General Management Plan
(Forest Service 1996, p. 2). Collection permits are not required for
activities contracted by or performed under agreement with the Forest
Service. The best available information indicates that collecting has
occurred before and after the Spring Mountains acastus checkerspot
butterfly was designated a sensitive species (see Factor B discussion
above); however, no permits have been issued to date.
Summary of Factor D
The current existing regulatory mechanism designed to regulate the
collection of Spring Mountains acastus checkerspot butterflies exists,
but there are no records of permits being issued for this purpose.
Despite the existence of the permitting program, collections of Spring
Mountains acastus checkerspot butterfly and other species of
butterflies have taken place without permits being issued. We are
unable at this time to determine the current population abundance or
trends for the Spring Mountains acastus checkerspot butterfly. We
concluded that collection is not a threat to the subspecies. Therefore,
we cannot conclude that existing regulatory mechanisms regarding
collection are inadequate. However, because butterfly collection is
known to occur in the Spring Mountains, we will work with the Forest
Service to enhance the effectiveness of their permitting program and
continue to monitor abundance and collection efforts. After reviewing
the best available commercial and scientific information, we conclude
that the inadequacy of existing regulatory mechanisms is not currently
a threat to the Spring Mountains acastus checkerspot butterfly, nor is
it likely to become so because our analysis under the other Factors
concluded that there are no significant threats to the species.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Drought at All Sites
Drought is variously defined depending upon the temporal and
spatial scales of interest (Heim 2002, p. 1150; Passioura 2007, p.
113). We consider drought in the context of reduced water availability
that would affect Spring Mountains acastus checkerspot butterfly larval
host and nectar plants at a magnitude sufficient to cause a decline in
the population. Climate models show the southwestern United States has
transitioned into a more arid climate of drought that is predicted to
continue into the next century (Seager et al. 2007, p. 1181).
Reductions in butterfly populations due to drought have been
observed (Ehrlich et al. 1980, pp. 101-105; Thomas 1984, p. 344). In
2006, populations of many butterfly species were at low levels
throughout southern Nevada, south of the Great Basin, likely as a
result of drought conditions (Murphy 2006, p. 3). In 2007, other
species of butterflies in the Spring Mountains experienced population
declines, and these declines were hypothesized to be a result of
drought (DataSmiths 2007, p. 22). Because other species of butterflies
in the Spring Mountains experienced declines thought to be associated
with drought, we believe that drought could affect the Spring Mountains
acastus checkerspot butterfly similarly. However, we do not have
information about Spring Mountains acastus checkerspot butterfly
abundance trends as they relate to drought occurrences in order to
determine at this time if drought may affect the subspecies now or in
the future.
The Spring Mountains acastus checkerspot butterfly's larval host
plant, Chrysothamnus viscidiflorus, is classified as having a ``high''
drought tolerance (USDA Natural Resources Conservation Service (NRCS)
2011); however, certain soil characteristics, such as loam (a soil
consisting of a mixture of varying proportions of clay, silt, and
sand), can reduce its tolerance to drought (Sperry and Hacke 2002, p.
367). We do not have information on where such soil characteristics
occur in the Spring Mountains and whether they occur in Spring
Mountains acastus checkerspot butterfly habitat. Additionally, C.
viscidiflorus is at a competitive disadvantage for limited early spring
moisture because of its low leaf area (Miller 1988, p. 62). Drought can
cause butterfly host plants to mature early, which can reduce larval
food availability (Ehrlich et al. 1980, pp. 101-105; Weiss 1987, p.
165). The available information about drought does not indicate that
Spring Mountains acastus checkerspot butterfly host plants are maturing
early and therefore reducing larval food availability for the
subspecies. Therefore, we cannot speculate about the effects of drought
on the Spring Mountains acastus checkerspot butterfly.
Precipitation during the growing season for Chrysothamnus
viscidiflorus (April through July) has exhibited an overall decline
during the last decade at three climate stations in and around the
Spring Mountains (Service 2011c, pp. 1-3). The Spring Mountains acastus
checkerspot butterfly population may be experiencing drought conditions
associated with this decline in precipitation. However, because the
larval host plant is drought-tolerant and the available information
does not indicate how individual Spring Mountains acastus checkerspot
butterflies may be impacted by drought, we have determined that, based
on the best available scientific and commercial information, drought is
not a threat to the subspecies at this time, nor is it likely to become
a threat in the future.
Small Populations
Populations with small numbers of individuals have a higher risk of
extinction than populations with large numbers of individuals due to
random environmental events (Shaffer 1981, p. 131; Gilpin and Soule
1986, pp. 24-28; Shaffer 1987, pp. 69-75). The number of surveyed
individuals of Spring Mountains acastus checkerspot butterflies has
remained small over the last 5 years (Table 2); however the available
information does not indicate that historical or recent population size
for the Spring Mountains acastus checkerspot butterfly have declined
such that small population size may be a threat to the subspecies now,
nor is it likely to become so in the future.
We are unable at this time to determine with any certainty the
current population abundance or trends of the Spring Mountains acastus
checkerspot butterfly. At the four sites where survey data exist, it
appears that abundances have consistently been low. Surveying
[[Page 59370]]
for butterflies may pose difficulties because of low densities, limited
resources, route considerations, surveyor experience, and varying
weather conditions (Zonneveld et al. 2003, pp. 476-486). On the basis
of a review of the available information and given the uncertainty
about abundance and trends, we cannot conclude that small population
size is a threat to the subspecies at this time, nor does available
information indicate it is likely to become so in the future.
Vehicle and Hiking Traffic at the Griffith Peak Trail/Harris Spring
Road/Harris Mountain Road Colony Site
One researcher has hypothesized that disturbance by vehicle and
hiking traffic may threaten the Griffith Peak Trail/Harris Spring Road/
Harris Mountain Road colony site as a result of direct disturbance to
the butterflies by vehicles and hikers (Boyd 2009, pp. 3-4). Vehicles
and hikers could affect Spring Mountains acastus checkerspot
butterflies by altering the behavior of the butterflies and causing
adult mortality from crushing or collision. Road and trail use are
likely to continue into the future. The Harris Spring Road leads to
Harris Mountain Road, where Spring Mountains acastus checkerspot
butterflies have been observed (Boyd and Austin 2001, Figure 1). This
is a rough gravel road with switchbacks that restrict vehicle speeds.
Visitor use during weekdays is low (Service 2011, p. 1), but likely
increases on the weekends. Mortality caused by crushing or collision
with vehicles would likely be rare because vehicles are unlikely to
attain speeds beyond those that butterflies could escape from. Exposure
of Spring Mountains acastus checkerspot butterflies to disturbance from
hikers is insignificant because the best available data indicate that
disturbance is sporadic and limited, allowing sufficient time for
mating to occur. Studies of sagebrush checkerspot butterflies have
shown that they have a high breeding success (Shields 1967, pp. 90 and
123; Rhainds 2010, pp. 212-213), and Spring Mountains acastus
checkerspot butterflies are likely similar. After females mate, they
disperse to oviposit, apparently away from the colony site breeding
areas (Boyd and Austin 2001, p. 6; Boyd and Austin 2002, p. 5).
Disturbance by vehicles and hikers is localized, ongoing, and low in
intensity. Exposure of Spring Mountains acastus checkerspot butterflies
to these activities is insignificant based upon our review of the best
available information. Therefore, we have determined that disturbance
from vehicles and hikers is not a threat to the Spring Mountains
acastus checkerspot butterfly now, nor is it likely to be a threat in
the future.
Summary of Factor E
Drought has occurred and is expected to continue throughout the
range of the Spring Mountains acastus checkerspot butterfly and may
negatively impact the subspecies. However, the larval host plant is
drought-tolerant, and the available information does not indicate that
individual Spring Mountains acastus checkerspot butterfly populations
have been impacted by drought such that drought is a threat to the
Spring Mountains acastus checkerspot butterfly now, nor is it likely to
become a threat in the future. The available information does not
indicate that small population size is a threat to the subspecies at
this time, nor is it likely to become so in the future given the
uncertainty about abundance and number of colonies. In addition, the
available information indicates that disturbance from vehicles and
hikers is not a threat to the Spring Mountains acastus checkerspot
butterfly because disturbance by vehicles and hikers is localized,
ongoing, and low in intensity. Based on our review of the best
available scientific and commercial information, there is no indication
that other natural or manmade factors are a threat to the subspecies at
this time, nor are they likely to become so in the future.
Cumulative Effects From Factors A Through E
We considered whether there may be cumulative effects to the Spring
Mountains acastus checkerspot butterfly from the combined impacts of
potential threats such that even if each threat individually does not
result in population-level impacts, that cumulatively the effects may
be significant. We considered whether the combined effects of fire
suppression, collection, climate change, and small population size may
result in a significant impact to the Spring Mountains acastus
checkerspot butterfly. At this time, given the complex and uncertain
nature of effects associated with climate change and the uncertainties
associated with information on the abundance and population trends of
the Spring Mountains acastus checkerspot butterfly, the best available
information does not indicate that synergistic interactions between
climate change and the other potential threats (fire suppression,
collection, and small population size) will impact the Spring Mountains
acastus checkerspot butterfly. Even though each of these potential
threats may result in an impact to the Spring Mountains acastus
checkerspot butterfly, the best available information does not indicate
that synergistic effects between fire suppression, collection, climate
change, and small population size are unlikely to result in a
significant overall population impact to the Spring Mountains acastus
checkerspot butterfly now, nor are they likely to do so in the future.
Finding
As required by the Act, we considered the five factors in assessing
whether the Spring Mountains acastus checkerspot butterfly is an
endangered or threatened species throughout all of its range. We
examined the best scientific and commercial information available
regarding the past, present, and future threats faced by the Spring
Mountains acastus checkerspot butterfly. We reviewed the petition,
information available in our files, other available published and
unpublished information, and we consulted with recognized Spring
Mountains acastus checkerspot butterfly experts and other Federal
agencies.
The term ``threatened species'' means any species (or subspecies
or, for vertebrates, distinct population segments) that is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. The Act does not define the
term ``foreseeable future.'' However, it likely describes the extent to
which the Service could reasonably rely on predictions about the future
in making determinations about the future conservation status of the
species.
In considering the foreseeable future as it relates to the status
of the Spring Mountain Acastus butterfly we considered the best
available scientific and commercial historical and current data to
identify any existing trends or indications that conditions are likely
to change in the future. We considered how current stressors are
affecting the species and if that information indicates any changes in
those stressors in the future. Thus the foreseeable future includes
consideration of the ongoing effects of current stressors and whether
there are likely to be any changes in the stressor in the future that
will result in population level effects.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the stressors
to the subspecies or its habitat are not of sufficient imminence,
intensity, or
[[Page 59371]]
magnitude to indicate that the Spring Mountains acastus checkerspot
butterfly is in danger of extinction (endangered), or likely to become
endangered within the foreseeable future (threatened), throughout all
or a significant portion of its range. While the best available
information indicates that survey numbers are low, it does not suggest
a significant change in distribution or abundance of the Spring
Mountains acastus checkerspot butterfly. Further, the best available
information does not indicate that any threats are acting on the
subspecies. Fire suppression has impacted other butterfly species in
the Spring Mountains, but the best available information does not
indicate that the larval host plant for the Spring Mountains acastus
checkerspot butterfly has been reduced in abundance and distribution as
a result of fire suppression. Additionally, while we are aware of
butterfly collection in the Spring Mountains, the best available
information does not indicate that population abundances of the Spring
Mountains acastus checkerspot butterfly are being negatively impacted
by collection. We are currently working with the Forest Service to
address collection permitting and prohibitions to avoid any potential
future threats that could occur from collection. Additionally, the best
available information does not indicate that any of these stressors are
likely to change such that they are likely to have population level
impacts on the subspecies in the future. Therefore, we find that
listing the Spring Mountains acastus checkerspot butterfly as an
endangered or threatened species is not warranted throughout all of its
range at this time.
Significant Portion of the Range
Under the Act and our implementing regulations, a species may
warrant listing if it is an endangered or threatened species throughout
all or a significant portion of its range. The Act defines ``endangered
species'' as any species which is ``in danger of extinction throughout
all or a significant portion of its range,'' and ``threatened species''
as any species which is ``likely to become an endangered species within
the foreseeable future throughout all or a significant portion of its
range.'' The definition of ``species'' is also relevant to this
discussion. The Act defines ``species'' as follows: ``The term
`species' includes any subspecies of fish or wildlife or plants, and
any distinct population segment of any species of vertebrate fish or
wildlife which interbreeds when mature.'' The phrase ``significant
portion of its range'' (SPR) is not defined by the statute, and we have
never addressed in our regulations: (1) The consequences of a
determination that a species is either endangered or likely to become
so throughout a significant portion of its range, but not throughout
all of its range; or (2) what qualifies a portion of a range as
``significant.''
In determining whether the Spring Mountains acastus checkerspot
butterfly is an endangered or threatened species in a significant
portion of its range, we first addressed whether any portions of the
range of the Spring Mountains acastus checkerspot butterfly warrant
further consideration. We evaluated the current range of the Spring
Mountains acastus checkerspot butterfly to determine if there is any
apparent geographic concentration of the primary stressors potentially
affecting the subspecies. We found the stressors are not of sufficient
imminence, intensity, or magnitude, and are not geographically
concentrated such that it warrants evaluating whether a portion of the
range is significant under the Act.
We do not find that the Spring Mountains acastus checkerspot
butterfly is in danger of extinction now, nor is likely to become
endangered within the foreseeable future, throughout all or a
significant portion of its range. Therefore, listing the Spring
Mountains acastus checkerspot butterfly as an endangered or threatened
species 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 Spring Mountains acastus checkerspot
butterfly to our Nevada Fish and Wildlife Offices (see ADDRESSES
section) whenever it becomes available. New information will help us
monitor the Spring Mountains acastus checkerspot butterfly and
encourage its conservation. If an emergency situation develops for the
Spring Mountains acastus checkerspot butterfly or any other species, we
will act to provide immediate protection.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Nevada Fish and
Wildlife Office (see ADDRESSES section).
Authors
The primary authors of this notice are the staff members of the
Nevada Fish and Wildlife Office and the Pacific Southwest Regional
Office.
Authority
The authority for this section is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: September 19, 2012.
Rowan W. Gould,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2012-23739 Filed 9-26-12; 8:45 am]
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