Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Mt. Charleston Blue Butterfly as Endangered or Threatened, 12667-12683 [2011-4884]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 76, Number 45 (Tuesday, March 8, 2011)]
[Proposed Rules]
[Pages 12667-12683]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-4884]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8-ES-2010-0028; MO 92210-0-0008]


Endangered and Threatened Wildlife and Plants; 12-Month Finding 
on a Petition To List the Mt. Charleston Blue Butterfly as Endangered 
or Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the Fish and Wildlife Service (Service), announce a 12-
month finding on a petition to list the Mt. Charleston blue butterfly 
(Plebejus shasta charlestonensis) (formerly in genus Icaricia) as 
endangered or threatened under the Endangered Species Act of 1973, as 
amended. After review of all available scientific and commercial 
information, we find that listing the Mt. Charleston blue butterfly is 
warranted. Currently, however, listing of the Mt. Charleston blue is 
precluded by higher priority actions to amend the Lists of Endangered 
and Threatened Wildlife and Plants. Upon publication of this 12-month 
petition finding, we will add the Mt. Charleston blue butterfly to our 
candidate species list. If an emergency situation develops with this 
subspecies that warrants an emergency listing, we will act immediately 
to provide additional protection. We will develop a proposed rule to 
list this subspecies as our priorities allow. We will make any 
determination on critical habitat during development of the proposed 
listing rule.

DATES: The finding announced in the document was made on March 8, 2011.

ADDRESSES: This finding is available on the Internet at https://www.regulations.gov at Docket Number FWS-R8-ES-2010-0028 and at https://www.fws.gov/nevada. 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: Jill Ralston, Deputy Field Supervisor, 
Nevada Fish and Wildlife Office (see ADDRESSES); by telephone at (702) 
515-5230; or by facsimile at (702) 515-5231. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at (800) 877-8339.

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(B) of the Endangered Species Act of 1973, as 
amended (Act) (16 U.S.C. 1531 et seq.), requires that, for any petition 
containing substantial scientific or commercial information indicating 
that listing the species may be warranted, we make a finding within 12 
months of the date of the receipt of the petition. In this finding, we 
determine that the petitioned action is: (a) Not warranted, (b) 
warranted, or (c) warranted, but the immediate proposal of a regulation 
implementing the petitioned action is precluded by other pending 
proposals to determine whether species are endangered or threatened, 
and expeditious progress is being made to add or remove qualified 
species from the Federal Lists of Endangered and Threatened Wildlife 
and Plants. Section 4(b)(3)(C) of the Act requires that we treat a 
petition for which the requested action is found to be warranted but 
precluded as though resubmitted on the date of such finding, that is, 
requiring a subsequent finding to be made within 12 months. We must 
publish these 12-month findings in the Federal Register.

Previous Federal Actions

    On October 20, 2005, we received a petition dated October 20, 2005, 
from The Urban Wildlands Group, Inc., requesting that we emergency list 
the Mt. Charleston blue butterfly (Mt. Charleston blue) (Plebejus 
shasta charlestonensis) (formerly in genus Icaricia) as an endangered 
or threatened species. In a letter dated April 20, 2006, we responded 
to the petitioner that our initial review did not indicate that an 
emergency situation existed, but that if conditions changed an 
emergency rule could be developed. On May 30, 2007, we published a 90-
day petition finding (72 FR 29933) in which we concluded that the 
petition provided substantial information indicating that listing of 
the Mt. Charleston blue may be warranted, and we initiated a status 
review. On February 17, 2010, the Center for Biological Diversity filed 
a complaint in United States District Court, Eastern District of 
California, indicating that the Service failed to take required actions 
on seven separate petitions for listed species found throughout the 
western United States including the Mt. Charleston blue. On April 26, 
2010, CBD amended its complaint in Center for Biological Diversity v. 
Salazar, U.S. Fish and Wildlife Service, Case No.: 1:10-cv-230-PLF 
(D.D.C.), adding an allegation that the Service failed to issue its 12-
month petition finding on the Mount Charleston blue butterfly within 
the mandatory statutory timeframe. This notice constitutes the 12-month 
finding on the October 20, 2005, petition to list the Mt. Charleston 
blue as endangered or threatened.

Species Information

Taxonomy
    The Mt. Charleston blue is a distinctive subspecies of the wider 
ranging Shasta blue butterfly (Plebejus shasta), which is a member of 
the Lycaenidae family. Pelham (2008, pp. 25-26) recognized seven 
subspecies of Shasta blue: P. s. shasta, P. s. calchas, P. s. 
pallidissima, P. s. minnehaha, P. s. charlestonensis, P. s. 
pitkinensis, and P. s. platazul. The Mt. Charleston blue is known only 
from the high elevations of the Spring Mountains, located approximately 
25 miles (mi) (40 kilometers (km)) west of Las Vegas in Clark County, 
Nevada (Austin 1980, p. 20; Scott 1986, p. 410). The first mention of 
the Mt. Charleston blue as a unique taxon was in 1928 by Garth, who 
recognized it as distinct from the species Shasta blue (Austin 1980, p. 
20). Howe, in 1975 (as cited in Austin 1980, p. 20), described 
specimens from the Spring Mountains as P. s. shasta form comstocki. 
However, in 1976, Ferris (as cited in Austin 1980, p. 20) placed the 
Mt. Charleston blue with the wider ranging Minnehaha blue subspecies. 
Finally, Austin asserted that Ferris had not included populations from 
the Sierra Nevada in his study, and that in light of the geographic 
isolation and distinctiveness of the Shasta blue population in the 
Spring Mountains and the presence of at least three other well-defined 
races of butterflies endemic to the area, it was appropriate to name 
this population as the individual subspecies Mt. Charleston blue (P. s. 
charlestonensis) (Austin 1980, p. 20). Our use of the genus name 
Plebejus, rather than the synonym Icaricia, reflects recent treatments 
of butterfly taxonomy (Opler and Warren 2003, p. 30; Pelham 2008, p. 
265).

[[Page 12668]]

    The wingspan of Shasta blue species is 0.75 to 1 inch (in) (19 to 
26 millimeters (mm)) (Opler 1999, p. 251). Males and females of Shasta 
blue are dimorphic. The upperside of males is dark to dull iridescent 
blue, and females are brown with a blue overlay. The species has a 
discal black spot on the forewing and a row of submarginal black spots 
on the hindwing. The underside is gray, with a pattern of black spots, 
brown blotches, and pale wing veins to give it a mottled appearance. 
The underside of the hindwing has an inconspicuous band of submarginal 
metallic spots (Opler 1999, p. 251). Based on morphology, the Mt. 
Charleston blue appears to be most closely related to the Great Basin 
populations of Minnehaha blue (Austin 1980, p. 23) and can be 
distinguished from other Shasta blue subspecies by the presence of 
sharper and blacker post medial spots on the underside of the hindwing 
(Scott 1986, p. 410).
Biology
    The Mt. Charleston blue is generally thought to diapause (a period 
of suspended growth or development similar to hibernation) at the base 
of its larval host plant, Torrey's milkvetch (Astragalus calycosus var. 
calycosus), or in the surrounding substrate. The pupae of some 
butterfly species are known to persist in diapause up to 5 to 7 years 
(Scott 1986, p. 28). The number of years the Mt. Charleston blue can 
remain in diapause is unknown. Local experts have speculated that the 
Mt. Charleston blue may only be able to diapause for one season. 
However, in response to unfavorable environmental conditions, it is 
hypothesized that a prolonged diapause period may be possible (Scott 
1986, pp. 26-30; Murphy 2006, p. 1; Datasmiths 2007, p. 6; Boyd and 
Murphy 2008, p. 22).
    The typical flight and breeding period for the butterfly is early 
July to mid-August with a peak in late July, although the subspecies 
has been observed as early as mid-June and as late as mid-September 
(Austin 1980, p. 22; Boyd and Austin 1999, p. 17; Forest Service 2006a, 
p. 9). As with most butterflies, the Mt. Charleston blue typically 
flies during sunny conditions, which are particularly important for 
this subspecies given the cooler air temperatures at high elevations 
(Weiss et al. 1997, p. 31). Excessive winds also deter flight of most 
butterflies, although Weiss et al. (1997, p. 31) speculate this may not 
be a significant factor for the Mt. Charleston blue given its low-to-
the-ground flight pattern.
    Like all butterfly species, both the phenology (timing) and number 
of Mt. Charleston blue individuals that emerge and fly to reproduce 
during a particular year are reliant on the combination of many 
environmental factors that may constitute a successful (``favorable'') 
or unsuccessful (``poor'') year for the subspecies. Other than 
observations by surveyors, little information is known regarding these 
aspects of the subspecies' biology, since the key determinants for the 
interactions among the butterfly's flight and breeding period, larval 
host plant, and environmental conditions have not been specifically 
studied. Observations indicate that above or below average 
precipitation, coupled with above or below average temperatures, 
influence the phenology of this subspecies (Weiss et al. 1997, pp. 2-3 
and 32; Boyd and Austin 1999, p. 8) and are likely responsible for the 
fluctuation in population numbers from year to year (Weiss et al. 1997, 
pp. 2-3 and 31-32).
    Most butterfly populations exist as regional metapopulations 
(groups of spatially separated populations that may function as single 
populations due to occasional interbreeding) (Murphy et al. 1990, p. 
44). Boyd and Austin (1999, pp. 17 and 53) indicate this is true of the 
Mt. Charleston blue. Small habitat patches tend to support smaller 
butterfly populations that are frequently extirpated by events that are 
part of normal variation (Murphy et al. 1990, p. 44). Boyd and Austin 
(1999, p. 17) suggest smaller colonies of the Mt. Charleston blue may 
be ephemeral in the long term, with the larger colonies of the 
subspecies more likely than smaller populations to persist in ``poor'' 
years, when environmental conditions do not support the emergence, 
flight, and reproduction of individuals. The ability of the Mt. 
Charleston blue to move between habitat patches has not been studied; 
however, field observations suggest the subspecies has low vagility 
(capacity or tendency of a species to move about or disperse in a given 
environment), on the order of 10 to 100 meters (m) (33 to 330 feet 
(ft)) (Weiss et al. 1995, p. 9), and nearly sedentary behavior 
(Datasmiths 2007, p. 21; Boyd and Murphy 2008, pp. 3 and 9). 
Furthermore, dispersal of lycaenid butterflies, in general, is limited 
and on the order of hundreds of meters (Cushman and Murphy 1993, p. 
40). Based on this information, the likelihood of long-distance 
dispersal is low for the Mt. Charleston blue.
Habitat
    Weiss et al. (1997, pp. 10-11) describe the natural habitat for the 
Mt. Charleston blue butterfly as relatively flat ridgelines above 2,500 
m (8,200 ft), but isolated individuals have been observed as low as 
2,000 m (6,600 ft). Boyd and Murphy (2008, p. 19) indicate that areas 
occupied by the subspecies feature exposed substrates with limited or 
no canopy cover or shading, and are on flats or mild slopes with 
moderate aspects. Like most butterfly species, the Mt. Charleston blue 
is dependent on plants both during larval development (larval host 
plants) and the adult butterfly flight period (nectar plants). The Mt. 
Charleston blue requires areas that support Torrey's milkvetch, the 
only known larval host plant for the subspecies (Weiss et al. 1994, p. 
3; Weiss et al. 1997, p. 10; Datasmiths 2007, p. 21), as well as 
primary nectar plants. Torrey's milkvetch and Clokey fleabane (Erigeron 
clokeyi) are the primary nectar plants for the subspecies; however, 
butterflies have also been observed nectaring on Lemmon's bitterweed 
(Hymenoxys lemmonii) and Aster sp. (Weiss et al. 1994, p. 3; Boyd 2005, 
p. 1; Boyd and Murphy 2008, p. 9).
    The best available habitat information relates mostly to the Mt. 
Charleston blue's larval host plant, with little to no information 
available characterizing the butterfly's interactions with its known 
nectar plants or other elements of its habitat; thus, the habitat 
information discussed in this document centers on Torrey's milkvetch. 
Studies are currently underway to better understand the habitat 
requirements and preferences of the Mt. Charleston blue (Thompson and 
Garrett 2010, p. 2; Pinyon 2010a, p. 1). Torrey's milkvetch is a small, 
low-growing, perennial herb that grows in open areas between 5,000 to 
10,800 ft (1,520 to 3,290 m) in subalpine, bristlecone, and mixed-
conifer vegetation communities of the Spring Mountains. Within the 
alpine and subalpine range of the Mt. Charleston blue, Weiss et al. 
(1997, p. 10) observed the highest densities of Torrey's milkvetch in 
exposed areas and within canopy openings and lower densities in 
forested areas.
    Weiss et al. (1997, p. 31) describe favorable habitat for the Mt. 
Charleston blue as having high densities (more than 10 plants per 
square meter) of Torrey's milkvetch. Weiss et al. (1995, p. 5) and 
Datasmiths (2007, p. 21) suggest that in some areas butterfly habitat 
may be dependent on old or infrequent disturbances that create open 
areas. Vegetation cover within disturbed patches naturally becomes 
higher over time through natural succession, gradually becoming less 
favorable to the butterfly. Therefore, we conclude that open areas with 
relatively little grass cover and visible mineral soil and high

[[Page 12669]]

densities of host plants support the highest densities of butterflies 
(Boyd 2005, p. 1; Service 2006a, p. 1). During 1995, an especially high 
population year, Mt. Charleston blue were observed in small habitat 
patches and in open forested areas where Torrey's milkvetch was present 
in low densities, on the order of 1 to 5 plants per square meter (Weiss 
et al. 1997, p. 10; Newfields 2006, pp. 10 and C5). Therefore, areas 
with lower densities of the host plant may also be important to the 
subspecies, as these areas may be intermittently occupied or may be 
important for dispersal.
    Fire suppression and other management practices have likely limited 
the formation of new habitat for the Mt. Charleston blue. The U.S. 
Forest Service (USFS) began suppressing fires on the Spring Mountains 
in 1910 (Entrix 2007, p. 111). Throughout the Spring Mountains, fire 
suppression has resulted in higher densities of trees and shrubs (Amell 
2006, pp. 2-3) and a transition to a closed-canopy forest with shade-
tolerant understory species (Entrix 2007, p. 112) that is generally 
less suitable for the Mt. Charleston blue. Boyd and Murphy (2008, pp. 
23 and 25) hypothesized that the loss of presettlement vegetation 
structure over time has caused the Mt. Charleston blue's metapopulation 
dynamics to collapse in Upper Lee Canyon. Similar losses of suitable 
butterfly habitat in woodlands and their negative effect on butterfly 
populations have been documented (Thomas 1984, pp. 337-338). Natural 
landscape processes have been modified in the Spring Mountains. Now, 
the disturbed landscape at the Las Vegas Ski and Snowboard Resort 
(LVSSR) provides important habitat for the Mt. Charleston blue (The 
Urban Wildlands Group, Inc. 2005, p. 2). Periodic maintenance (removal 
of trees and shrubs) of the ski runs has effectively arrested forest 
succession on the ski slopes and serves to maintain conditions 
favorable to the Mt. Charleston blue, and to its host and nectar 
plants. However, the ski runs are not specifically managed to benefit 
habitat for this subspecies and operation activities regularly modify 
Mt. Charleston blue habitat or prevent host plants from reestablishing 
in disturbed areas.
Range and Current Distribution
    Based on current and historical occurrences or locations documented 
in the petition or identified in the State of Nevada Natural Heritage 
Program database (The Urban Wildlands Group, Inc. 2005, pp. 1-3; 
Service 2006b, pp. 2-4), the geographic range of the Mt. Charleston 
blue is primarily on the east side of the Spring Mountains, centered on 
lands managed by the USFS in the Spring Mountains National Recreation 
Area of the Humboldt-Toiyabe National Forest within Upper Kyle and Lee 
Canyons, Clark County, Nevada. The majority of the occurrences or 
locations are in the Upper Lee Canyon area, while a few are in Upper 
Kyle Canyon. Table 1 lists the various locations of the Mt. Charleston 
blue that constitute the subspecies' current and historical range.

     Table 1--Locations or Occurrences of the Mt. Charleston Blue Butterfly Since 1928 and the Status of the
                                           Butterfly at the Locations
----------------------------------------------------------------------------------------------------------------
                                       First/last  Most recent
            Location name                 time        survey             Status             Primary references
                                        observed     year(s)
----------------------------------------------------------------------------------------------------------------
1. South Loop Trail, Upper Kyle         1995/2010  2007, 2008,  Known occupied, adults   NNHP 2007; Weiss et al.
 Canyon.                                                  2010   consistently observed.   1997; Kingsley 2007;
                                                                                          Boyd 2006; Datasmiths
                                                                                          2007; SWCA 2008,
                                                                                          Pinyon 2010a, Thompson
                                                                                          and Garrett 2010.
2. LVSSR, Upper Lee Canyon..........    1963/2010  2007, 2008,  Known occupied, adults   NNHP 2007; Weiss et al.
                                                          2010   consistently observed.   1994; Weiss et al.
                                                                                          1997; Boyd and Austin
                                                                                          2002; Boyd 2006;
                                                                                          Newfields 2006;
                                                                                          Datasmiths 2007; Boyd
                                                                                          and Murphy 2008,
                                                                                          Thompson and Garrett
                                                                                          2010.
3. Foxtail Upper Lee Canyon.........    1995/1998   2006, 2007  Presumed occupied,       NNHP 2007; Boyd and
                                                                 adults intermittently    Austin 1999; Boyd
                                                                 observed.                2006; Datasmiths 2007.
4. Youth Camp, Upper Lee Canyon.....    1995/1995   2006, 2007  Presumed occupied,       Weiss et al. 1997; Boyd
                                                                 adults intermittently    2006; Datasmiths 2007.
                                                                 observed.
5. Gary Abbott, Upper Lee Canyon....    1995/1995   2006, 2007  Presumed occupied,       NNHP 2007; Weiss et al.
                                                                 adults intermittently    1997; Boyd 2006;
                                                                 observed.                Datasmiths 2007.
6. Lower LVSSR Parking, Upper Lee       1995/2002   2007, 2008  Presumed occupied,       Urban Wildlands Group,
 Canyon.                                                         adults intermittently    Inc. 2005; Weiss et
                                                                 observed.                al. 1997; Boyd 2006;
                                                                                          Datasmiths 2007; Boyd
                                                                                          and Murphy 2008.
7. Mummy Spring, Upper Kyle Canyon      1995/1995         2006  Presumed occupied,       NNHP 2007; Weiss et al.
 \1\.                                                            adults intermittently    1997; Boyd 2006.
                                                                 observed.
8. Lee Meadows, Upper Lee Canyon....    1965/1995   2006, 2007  Presumed occupied,       NNHP 2007; Weiss et al.
                                                                 adults intermittently    1997; Boyd 2006;
                                                                 observed.                Datasmiths 2007.
9. Bonanza Trail....................    1995/1995   2006, 2007  Presumed occupied......  Weiss et al. 1997; Boyd
                                                                                          2006; Kingsley 2007.
10. Upper Lee Canyon holotype \1\...    1963/1976   2006, 2007  Presumed extirpated....  NNHP 2007; Weiss et al.
                                                                                          1997; Boyd 2006;
                                                                                          Datasmiths 2007.
11. Cathedral Rock, Kyle Canyon.....    1972/1972         2007  Presumed extirpated....  NNHP 2007; Weiss et al.
                                                                                          1997; Datasmiths 2007.
12. Upper Kyle Canyon Ski Area \1\..    1965/1972         1995  Presumed extirpated....  NNHP 2007; Weiss et al.
                                                                                          1997.
13. Old Town, Kyle Canyon \2\.......        1970s         1995  Presumed extirpated....  The Urban Wildlands
                                                                                          Group, Inc. 2005.
14. Deer Creek, Kyle Canyon.........         1950      unknown  Presumed extirpated....  NNHP 2007.
15. Willow Creek....................         1928      unknown  Presumed extirpated....  NNHP 2007; Weiss et al.
                                                                                          1997, Thompson and
                                                                                          Garrett 2010.
----------------------------------------------------------------------------------------------------------------
\1\ Location is not mentioned in the petition.
\2\ Location is not identified in the Nevada Natural Heritage Program database.


[[Page 12670]]

    We presume that the Mt. Charleston blue is extirpated from a 
location when it has not been recorded at that location through formal 
surveys or informal observation for more than 20 years. We selected a 
20-year time period because it would likely allow for local extirpation 
and recolonization events (metapopulation dynamics) to occur and would 
be enough time for succession or other vegetation shifts to render the 
habitat unsuitable (see discussion in ``Biology'' and ``Habitat'' 
sections above). Using this criterion, the Mt. Charleston blue is 
considered to be ``presumed extirpated'' from 6 of the 14 known 
locations (Locations 9-14 in Table 1) (The Urban Wildlands Group, Inc. 
2005, pp. 1-3; Service 2006b, pp. 8-9). Of the remaining eight 
locations, six locations or occurrences are ``presumed occupied'' by 
the subspecies (Locations 3-8 in Table 1) (The Urban Wildlands Group, 
Inc. 2005, pp. 1-3; Service 2006b, pp. 7-8).
    This category is defined as a location within the current known 
range of the subspecies where adults have been intermittently observed 
and there is a potential for diapausing larvae to be present. The 
butterfly likely exhibits metapopulation dynamics at these locations, 
where the subspecies is subject to local extirpation, with new 
individuals emigrating from nearby ``known occupied'' habitat, 
typically during years when environmental conditions are more favorable 
to emergence from diapause and the successful reproduction of 
individuals (see discussion in ``Habitat'' section above). At some of 
these presumed occupied locations (Locations 4, 5, 7, 8 and 9 in Table 
1), the Mt. Charleston blue has not been recorded through formal 
surveys or informal observation since 1995 by Weiss et al. (1997, pp. 
1-87). Currently, we consider the occurrence at Mummy Spring as 
presumed occupied; however, this location is not near known occupied 
habitat and may be extirpated.
    We consider the remaining two Mt. Charleston blue locations or 
occurrences to be ``known occupied'' (Locations 1 and 2 in Table 1). 
The South Loop Trail location in Upper Kyle Canyon (Location 1 in Table 
1) is considered known occupied because: (1) The butterfly was observed 
on the site in 1995, 2002, 2007, and 2010 (Service 2007, pp. 1-2; 
Kingsley 2007, p. 5; Pinyon 2010, pp. 1-2; Thompson and Garrett 2010, 
p. 5); and (2) the high quality of the habitat is in accordance with 
host plant densities of 10 plants per square meter as described in 
Weiss et al. (1997, p. 31; Kingsley 2007, pp. 5 and 10), and is in an 
area of relatively large size (18.7 acres (ac) (7.6 hectares (ha)) 
(SWCA 2008, pp. 2 and 5). The South Loop Trail area appears to be the 
most important remaining population area for the Mt. Charleston blue 
(Boyd and Murphy 2008, p. 21). The South Loop Trail runs along the 
ridgeline between Griffith Peak and Charleston Peak and is located 
within the Mt. Charleston Wilderness. This area was field mapped using 
a global positioning system unit and included the larval host plant, 
Torrey's milkvetch, as well as occurrences of two known nectar plants, 
Lemmon's bitterweed and Clokey fleabane (SWCA 2008, pp. 2 and 5). 
Adjacent to this ``known occupied'' habitat of 18.7 ac (7.6 ha) occurs 
approximately 40 ac (17 ha) of additional habitat containing Lemmon's 
bitterweed and Clokey fleabane, as well as a smaller patch of Torrey's 
milkvetch (1.6 ac) (0.65 ha) (SWCA 2008, pp. 2 and 5).
    We consider LVSSR in Upper Lee Canyon (Location 2 in Table 1) to be 
``known occupied'' because: (1) The butterfly was first recorded at 
LVSSR in 1963 (Austin 1980, p. 22) and has been consistently observed 
at LVSSR every year between 1995 and 2006 (with the exception of 1997 
when no surveys were performed, and in recent years when the species 
was not observed) (Service 2007, pp. 1-2) and in 2010 (Thompson and 
Garrett 2010, p. 5); and (2) the ski runs contain two areas of high-
quality butterfly habitat in accordance with host plant densities of 10 
plants per square meter as described in Weiss et al. (1997, p. 31). 
These areas are LVSSR 1(2.4 ac (0.97 ha)) and LVSSR 2 
(1.3 ac (0.53 ha)), which have been mapped using a global positioning 
system unit and field verified. Thus, across its current range, the Mt. 
Charleston blue is known to persistently occupy less than 22.4 ac (9.1 
ha) of habitat.
Status and Trends
    The Mt. Charleston blue has been characterized as particularly 
rare, but common in some years (Boyd and Austin 1999, p. 17; The Urban 
Wildlands Group, Inc. 2005, p. 2). The 1995 season was the last year 
the butterfly was present in high numbers. Variations in precipitation 
and temperature that affect both the Mt. Charleston blue and its larval 
host plant are likely responsible for the fluctuation in population 
numbers from year to year (Weiss et al. 1997, pp. 2-3 and 31-32). The 
total population of the Mt. Charleston blue is unknown. We do not have 
population estimates for the butterfly or specific information showing 
a change in numbers; however, it appears the population has declined 
since the last high-population year in 1995 (Murphy 2006, pp. 1-2).
    Recent survey information indicates the Mt. Charleston blue 
population appears to be extremely low. In 2006, surveys within 
presumed occupied habitat at LVSSR located one individual butterfly 
adjacent to a pond that holds water for snowmaking (Newfields 2006, pp. 
10, 13, and C5). In a later report, the accuracy of this observation 
was questioned and considered inaccurate (Newfields 2008, p. 27). In 
2006, Boyd (2006, pp. 1-2) conducted focused surveys for the subspecies 
at nearly all previously known locations and within potential habitat 
along Griffith Peak, North Loop Trail, Bristlecone Trail, and South 
Bonanza Trail but did not observe the butterfly at any of these 
locations. In 2007, surveys were again conducted in previously known 
locations in Upper Lee Canyon and LVSSR, but no butterflies were 
recorded (Datasmiths 2007, p. 1; Newfields 2008, pp. 21-24). In 2007, 
two Mt. Charleston blue butterflies were sighted on different dates at 
the same location on the South Loop Trail in Upper Kyle Canyon 
(Kingsley 2007, p. 5). In 2008, butterflies were not observed during 
focused surveys of Upper Lee Canyon and the South Loop Trail (Boyd and 
Murphy 2008, pp. 1-3; Boyd 2008, p. 1; SWCA 2008, p. 6), although it is 
possible adult butterflies may have been missed on South Loop Trail 
because the surveys were performed very late in the season. No formal 
surveys were conducted in 2009; however, no individuals were seen 
during the few informal attempts made to observe the species.
    Adults of the Mt. Charleston blue were most recently observed in 
2010 in the South Loop Trail area and LVSSR. From reports of several 
adult surveys in July and August at the South Loop area (Thompson and 
Garrett 2010; Pinyon 2010a, pp. 1-2; Pinyon 2010b), the highest total 
counted among the days this area was surveyed was 17 on July 28 (Pinyon 
2010b). One adult was observed in Lee Canyon at LVSSR on July 23, 2010, 
but no other adults were detected at LVSSR on surveys conducted August 
2, 9, and 18, 2010 (Thompson and Garrett 2010, pp. 4-5). Final reports 
have not been completed for these projects and the results are 
considered preliminary.
    The availability of known larval and nectar plants does not appear 
to be correlated to the recent low population numbers of the butterfly 
as the host plants continue to persist at previously occupied locations 
and throughout the Spring Mountains. The low number of butterflies 
observed during the 2006,

[[Page 12671]]

2007, 2008, and 2010 seasons could be partially attributed to extreme 
weather (e.g., heavy precipitation events and drought). Prior to 2005, 
there were numerous years of drought, followed by a record snow in the 
winter of 2004-2005. In 2006 and 2007, the area experienced dry winters 
and springs and severe thunderstorms during the summers and flight 
periods. Based on the available survey information, the low number of 
sightings in recent years is likely the result of an already small 
population size, exacerbated by unfavorable weather conditions. 
Historical and recent survey information for this subspecies is very 
limited or unavailable in regard to population data. Thus, we focused 
our threats analysis on assessed threats at known occupied and presumed 
occupied locations (summarized in Table 1).

Summary of Information Pertaining to the Five Threat 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 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.
    We summarize below information regarding the status of and threats 
to this subspecies in relation to the five factors in section 4(a)(1) 
of the Act. In making our 12-month finding, we considered and evaluated 
all scientific and commercial information in our files, including 
information received in response to our request for information in the 
notice of 90-day petition finding and initiation of status review (72 
FR 29933), and additional scientific information from ongoing species 
surveys as they became available. In response to the information 
request, we received two letters from private organizations that 
provided information and comments on the Mt. Charleston blue.

Factor A: The Present or Threatened Destruction, Modification, or 
Curtailment of the Species' Habitat or Range

Fire Suppression, Succession, and Nonnative Species
    Butterflies have extremely specialized habitat requirements (Thomas 
1984, p. 337). Changes in vegetation structure and composition as a 
result of natural processes are a serious threat to butterfly 
populations because these changes can disrupt specific habitat 
requirements (Thomas 1984, pp. 337-341; Thomas et al. 2001, pp. 1791-
1796). Cushman and Murphy (1993, p. 4) determined 28 at-risk lycaenid 
butterfly species, including the Mt. Charleston blue, to be dependent 
on one or two closely related host plants. Many of these host plants 
are dependent on early successional environments. Butterflies that 
specialize on such plants must track an ephemeral resource base that 
itself depends on unpredictable and perhaps infrequent ecosystem 
disturbances. For such butterfly species, local extinction events are 
both frequent and inevitable (Cushman and Murphy 1993, p. 4). The Mt. 
Charleston blue may, in part, depend on disturbances that open up the 
subalpine canopy and create conditions more favorable to its host 
plant, Torrey's milkvetch, and nectar resources (Weiss et al. 1995, p. 
5; Boyd and Murphy 2008, pp. 22-28) (see Habitat section, above).
    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 
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). 
Frequent low-severity fires would have maintained an open forest 
structure characterized by uneven-aged stands of fire-resistant 
ponderosa pine trees (Amell 2006, p. 5) in lower elevations. The lower-
elevation habitats of the Mt. Charleston blue has likely been the most 
affected by fire suppression as indicated by Provencher's 2008 Fire 
Regime Condition Class analysis of the Spring Mountains (p. 18) in 
which higher-elevation biophysical settings departed less from the 
natural range of variability than those at middle elevations.
    Large-diameter ponderosa pine trees with multiple fire scars in 
upper Lee and Kyle Canyons indicate that low-severity fires 
historically burned through mixed-conifer forests within the range of 
the Mt. Charleston blue (Amell 2006, p. 3). Open mixed-conifer forests 
in the Spring Mountains were likely characterized by more abundant and 
diverse understory plant communities compared to current conditions 
(Entrix 2007, pp. 73-78). These successional changes have been 
hypothesized to have contributed to the decline of the Mt. Charleston 
blue because of reduced densities of larval and nectar plants, 
decreased solar radiation, and inhibited butterfly movements that 
subsequently determine colonization or recolonization processes (Weiss 
et al. 1997, p. 26; Boyd and Murphy 2008, pp. 22-28). Boyd and Murphy 
(2008, p. 23) noted that important habitat characteristics required by 
Mt. Charleston blue--Torrey's milkvetch and preferred nectar plants 
occurring together in open sites not shaded by tree canopies--would 
have occurred more frequently across a more open, forested landscape 
compared to the current denser forested landscape. Not only would the 
changes in forest structure and understory plant communities result in 
habitat loss and degradation for the Mt. Charleston blue across a broad 
spatial scale, a habitat matrix dominated by denser forest also may be 
impacting key metapopulation processes by reducing probability of 
recolonization following local population extirpations in remaining 
patches of suitable habitat (Boyd and Murphy 2008, p. 25).
    The introduction of forbs, shrubs, and nonnative grasses can be a 
threat to butterfly populations because these species can compete with, 
and decrease, the quality and abundance of larval host plant and adult 
nectar sources. This has been observed for many butterfly species 
including the Quino checkerspot butterfly (Euphydryas editha quino) (62 
FR 2313; January 16, 1997) and Fender's blue butterfly (Icaricia 
icarioides fenderi) (65 FR 3875; January 25, 2000). Datasmiths (2007, 
p. 21) also suggest suitable habitat patches of Torrey's milkvetch are 
often, but not exclusively, associated with older or infrequent 
disturbance. Weiss et al. (1995, p. 5) note that a colony once existed 
on the Upper Kyle Canyon Ski Area (Location 11 in Table 1), but since 
the ski run was abandoned no butterflies have been collected there 
since 1965. Boyd and Austin (2002, p. 13) observe that the butterfly 
was common at Lee Meadows (Location 8 in Table 1) in the 1960s, but 
became uncommon at the site because of succession and a potential lack 
of disturbance. Using an analysis of host plant density, Weiss et al. 
(1995 p. 5) concluded that Lee Meadows does not have enough host plants 
to support a population over the long term.

[[Page 12672]]

Succession, coupled with the introduction of nonnative species, is also 
believed to be the reason the Mt. Charleston blue is no longer present 
at the old town site in Kyle Canyon (Location 12 in Table 1) and at the 
holotype site in Upper Lee Canyon (Location 9 in Table 1) (Urban 
Wildlands Group, Inc. 2005, p. 3; Boyd and Austin 1999, p. 17).
    Management of nonnative species within butterfly habitat is a 
threat to the butterfly. As mentioned previously (see Habitat section), 
periodic maintenance (removal of trees and shrubs) of the ski runs has 
effectively arrested succession on the ski slopes and maintains 
conditions that can be favorable to the Mt. Charleston blue. However, 
the ski runs are not specifically managed to benefit habitat for this 
subspecies, and operation activities (including seeding of nonnative 
species) regularly modify butterfly habitat or prevent host plants from 
reestablishing in disturbed areas. Weiss et al. (1995, pp. 5-6) suggest 
that the planting of annual grasses and Melilotus for erosion control 
at LVSSR is a threat to Mt. Charleston blue habitat. Titus and Landau 
(2003, p. 1) observed that vegetation on highly and moderately 
disturbed areas of the LVSSR ski runs are floristically very different 
from natural clearings in the adjacent forest that support the 
butterfly. Seeding nonnative species for erosion control was 
discontinued in 2005; however, because of erosion problems during 2006 
and 2007, and the lack of native seed, LVSSR resumed using a nonnative 
seed mix, particularly in the lower portions of the ski runs (not 
adjacent to Mt. Charleston blue habitat) where erosion problems 
persist.
    Based on available information, it appears that in at least four of 
the six locations where the butterfly historically occurred, suitable 
habitat is no longer present due to vegetation changes attributable to 
succession, the introduction of nonnative species, or a combination of 
the two.
Recreation Development Projects
    As previously detailed in the ``Range and Current Distribution'' 
section of this finding, the Mt. Charleston blue is a narrow endemic 
subspecies that is currently known to occupy two locations and presumed 
to occupy six others. This distribution is on lands managed by the USFS 
(including LVSSR, which is operated under a USFS special use permit) in 
the Spring Mountains National Recreation Area within the Humboldt-
Toiyabe National Forest. We analyzed USFS' recreation development 
projects from 2000 to 2007 to determine if habitat impacts resulting 
from completed and pending projects are a threat to the subspecies at 
these locations, as cited in the petition and referenced in the 90-day 
petition finding. In addition to a fuels reduction project, we 
identified seven projects that have removed or impacted butterfly 
habitat in Upper Lee Canyon, where the butterfly is known or presumed 
to be present. We determined that an eighth impact identified in the 
petition and 90-day petition finding, an unsanctioned trail that 
bisects habitat on the South Loop Trail in Upper Kyle Canyon, is not a 
threat to the butterfly (Kingsley 2007, p. 17).
    In general, it is difficult to know the full extent of impacts to 
the Mt. Charleston blue as a result of these projects because butterfly 
habitat was not mapped for the majority of them nor were some project 
areas surveyed prior to implementation. The majority of impacts 
associated with these projects have not been mitigated, and some of the 
impacted areas have not recovered. Given the slow natural rate of 
recovery, the pace of restoration efforts (see Factor D), and the 
potential for recurrent disturbance at many of these sites, we do not 
expect these impacted areas to provide butterfly habitat for many years 
to come, unless noted below. The following is a summary of the 
recreation development projects that have removed or impacted Mt. 
Charleston blue habitat from 2000 to 2010.
    (1) During 2000 or 2001, a series of earthen berms were constructed 
at the top of a ski run at LVSSR. These berms were created by scraping 
topsoil from the ski run in an area known to support high densities of 
Torrey's milkvetch. This activity caused loss and degradation of an 
unknown area of presumed occupied butterfly habitat at LVSSR, Upper Lee 
Canyon (Location 2 in Table 1) (The Urban Wildlands Group, Inc. 2005, 
p. 3; Service 2006a, pp. 1-5). We assume, based on the level of soil 
disturbance, this activity would have also killed any larvae, pupae, or 
eggs present. Based on the best available information, Torrey's 
milkvetch has not recolonized the area (Service 2006a, pp. 1-5).
    (2) In 2003, the Lee Canyon water system was repaired and expanded, 
which included construction of new and replacement waterlines through 
presumed occupied butterfly habitat on Foxtail Ridge adjacent to the 
Lee Canyon Youth Camp and the lower LVSSR parking lot (Location 3 in 
Table 1) (Forest Service 2003a, pp. 1-6). Resource surveys did not 
include butterfly host plants, and the extent of impacts was not 
calculated (Forest Service 2003b, pp. 21-22). Based on the most recent 
survey, Torrey's milkvetch still occurs on Foxtail Ridge (Datasmiths 
2007, pp. 26-27), and it appears that the Lee Canyon water system 
project area has been recolonized by Torrey's milkvetch (Kingsley 2007, 
p. 17); however, the Mt. Charleston blue has not been observed at this 
location since 1998.
    (3) In 2004, the lower LVSSR parking lot was converted into a 
temporary water storage basin (Forest Service 2004a, p. 1). This 
activity included excavation of the parking lot and the construction of 
temporary berms to hold water. Surveys for butterfly host plants were 
not performed, but butterfly host plants were noted in the project area 
as part of a rare plant survey (Hiatt 2004, p. 4). Any larvae, pupae, 
and eggs, along with all vegetation and soil seed bank, would likely 
have been killed while the basin was filled with water. Approximately 2 
ac (0.81 ha) of presumed occupied butterfly habitat were impacted as a 
result of the project (Location 6 in Table 1) (The Urban Wildlands 
Group, Inc. 2005, p. 3). The parking lot continues to be used for 
overflow parking. Recent resource surveys of the area for the proposed 
expansion of the parking lot (see future projects discussion below) 
indicate host plants have not returned to the parking area and remain 
along the perimeter (Datasmiths 2007, pp. 26-27).
    (4) In 2004, the Entrance Walkway Grade Improvement Project 
permanently removed (by paving) 0.186 ac (0.075 ha) of Mt. Charleston 
blue presumed occupied habitat near the main LVSSR parking site for the 
construction of a walkway (Forest Service 2004b, pp. 21-22; Forest 
Service 2004c, pp. 1-3).
    (5) In 2004 and 2005, the LVSSR Snowmaking Line Replacement Project 
impacted approximately 7 ac (2.8 ha) of presumed occupied butterfly 
habitat on the ski runs (Forest Service 2006b, p. 1) and approximately 
0.2 ac (0.08 ha) of known occupied habitat at LVSSR, Upper Lee Canyon 
(Location 2 in Table 1) (The Urban Wildlands Group, Inc. 2005, p. 3; 
Service 2006a, pp. 1-5; Forest Service 2004c, pp. 1-3; Forest Service 
2004d, p. 9; Forest Service 2006b, pp. 1-9). Given the type of 
disturbance, we presume any butterfly larvae, pupae, and eggs would 
have been buried or crushed as a result of trenching and equipment 
access. Revegetation of butterfly habitat impacted from this 
construction was required (Forest Service 2004c, pp. 1-2; 2004d, p. 9-
10), but there are no records available in our files that indicate it 
has been completed (see Factor D).

[[Page 12673]]

    (6) In 2005, the chairlift 1 at LVSSR was replaced. All 
vegetation was removed within equipment travel corridors, laydown 
areas, and construction areas in approximately 4.5 ac (1.8 ha) of 
presumed occupied butterfly habitat (Location 2 in Table 1) (Forest 
Service 2006b, p. 2). Given the level of disturbance, we presume any 
butterfly larvae, pupae, and eggs would have been buried or crushed as 
a result of trenching and equipment access. Revegetation of butterfly 
habitat impacted from this construction was required (Forest Service 
2005c, p. 2; Forest Service 2005d, pp. 12-14; Forest Service 2005e, pp. 
11-12), but there are no records available in our files that indicate 
it has been completed (see Factor D).
    (7) Expansion of the snowmaking pond at LVSSR was first proposed in 
June 2005 and would have permanently impacted 0.48 ac (0.18 ha) of 
presumed occupied butterfly habitat (Forest Service 2005a, pp. 1-25). 
The project was revised to reduce impacts in December 2007 (Forest 
Service 2007b, pp. 1-31) and again in June 2009. Plans for 
implementation included measures to minimize the amount of area 
impacted and mitigate for the loss of any butterfly habitat (Forest 
Service 2009a, p. 18). Construction of the snowmaking pond expansion 
was initiated and completed in 2010. The construction footprint was 
adjacent to one patch of Torrey's milkvetch, and overlapped another 
patch (Forest Service 2010b, Figure 1). A total area of 0.055 ac (0.022 
ha) of Torrey's milkvetch habitat patches was impacted by pond 
expansion construction (Forest Service 2010b, Table 1). Recommendations 
to mitigate for impacted habitat have been prepared (Forest Service 
2010b, pp. 1-5) but not yet implemented. An additional patch of 
previously undocumented Torrey's milkvetch was observed within the 
construction zone in May 2010 (Forest Service 2010a, p. 2), and is not 
included as an area for which mitigation is to be performed (Forest 
Service 2010b, pp. 1-5).
    Future projects are also a threat to the Mt. Charleston blue and 
its habitat. Four recently approved or future projects could impact Mt. 
Charleston blue habitat in Upper Lee Canyon, and are summarized below.
    (1) Expansion of the lower parking lot at LVSSR was proposed in 
June 2005 (Forest Service 2005a, pp. 1-25) and, after revisions to 
reduce impacts to the subspecies' habitat, was reproposed in December 
2007 (Forest Service 2007b, pp. 1-31). Expansion of the lower LVSSR 
parking lot would result in the permanent loss of 2.4 ac (0.97 ha) of 
previously disturbed butterfly habitat and 0.81 ac (0.33 ha) of 
undisturbed presumed occupied butterfly habitat (Location 6 in Table 1) 
(Forest Service 2007b, p. 12). Planning and environmental documents are 
completed for the project; however, final authorization by the USFS has 
not occurred and is currently on hold due to concerns about impacts to 
Mt. Charleston blue (Forest Service 2009a, p. 1).
    (2) The snowmaking system improvements project (new snowmaking 
lines) at LVSSR was proposed in June 2005 (Forest Service 2005a, pp. 1-
2). As proposed, the snowmaking lines expansion project would have 
permanently impacted at that time approximately 8.9 ac (3.6 ha) of 
known occupied butterfly habitat along the two primary ski runs where 
known occupied habitat has been delineated for the Mt. Charleston blue 
(Location 2 in Table 1). The USFS stopped planning efforts for this 
project in 2007 based on the potential impacts to the Mt. Charleston 
blue (Forest Service 2007b, pp. 2).
    (3) A January 2008 draft Master Development Plan for LVSSR proposes 
to improve, upgrade, and expand the existing facilities to provide 
year-round recreational activities. The plan proposes to add winter 
activities such as tubing, MiniZ, snowshoeing, Nordic skiing, climbing 
wall, and Euro-bungee, by widening existing runs to create ``gladed'' 
areas that would provide larger sliding areas (Ecosign 2008, pp. I-3-I-
4). The plan proposes to add summer activities and facilities, 
including mountain biking and bike park, alpine slides, concerts, 
hiking, mountain boards, ziptreks, and stargazing (Ecosign 2008, pp. I-
3-I-4). Summer activities would impact the butterfly and its known 
occupied and presumed occupied habitat (Location 2 in Table 1) by 
attracting visitors in higher numbers during the time of year when 
larvae and host plants are especially vulnerable to trampling. The 
Master Development Plan is in draft form and has not yet been approved 
by the USFS; therefore, no estimate of the potential area of impact is 
available.
    (4) Currently the USFS is planning to restore eroded stream 
channels in Lee Meadows. Repairs to the channels are expected to impact 
presumed occupied butterfly habitat mapped at 1.2 ac (0.50 ha) 
(Location 8 in Table 1) (Forest Service 2009b, p. 10; Datasmiths 2007, 
p. 27). Project implementation began in 2010 and is expected to be 
completed in 2011, and includes measures to minimize impacts to, and 
compensate for the loss of, butterfly habitat (Forest Service 2009b, p. 
10).
Fuels Reduction Projects
    In December 2007, the USFS approved the Spring Mountains National 
Recreation Area Hazardous Fuels Reduction Project (Forest Service 
2007a, pp. 1-127). This project will result in tree removals and 
vegetation thinning in three presumed occupied butterfly locations in 
Upper Lee Canyon, including Foxtail Ridge, Lee Canyon Youth Camp, and 
Lee Meadows, and result in impacts to approximately 32 ac (13 ha) of 
presumed occupied habitat that has been mapped in Upper Lee Canyon 
(Locations 3, 4 and 8 in Table 1) (Forest Service 2007a, Appendix A-Map 
2; Datasmiths 2007, p. 26). Manual and mechanical clearing of shrubs 
and trees will be repeated on a 5- to 10-year rotating basis and will 
result in direct impacts to the butterfly and its habitat, including 
crushing or removal of host plants and diapausing larvae (if present). 
Implementation of this project began in the spring of 2008 throughout 
the Spring Mountains National Recreation Area, including Lee Canyon.
    Although Boyd and Murphy (2008, p. 26) recommended increased forest 
thinning to improve habitat quality for the Mt. Charleston blue, this 
project was designed to reduce wildfire risk to life and property in 
the Spring Mountains National Recreation Area wildland urban interface 
(Forest Service 2007a, p. 6), not to improve Mt. Charleston blue 
habitat. Mt. Charleston blues require larval host plants in exposed 
areas not shaded by forest canopy cover because canopy cover reduces 
solar exposure during critical larval feeding periods (Boyd and Murphy 
2008, p. 23). Shaded fuel breaks created for this project may not be 
open enough to create or significantly improve Mt. Charleston blue 
habitat. Also, shaded fuel breaks for this project are concentrated 
along access roads, property boundaries, campgrounds, picnic areas, 
administrative sites, and communications sites, and are not of 
sufficient spatial scale to reduce the threat identified above 
resulting from fire suppression and succession.
    Although this project may result in increased understory herbaceous 
plant productivity and diversity, there are short-term risks to the 
butterfly associated with project implementation. In recommending 
increased forest thinning to improve Mt. Charleston blue habitat, Boyd 
and Murphy (2008, p. 26) cautioned that thinning treatments would need 
to be implemented carefully to minimize short-term disturbance

[[Page 12674]]

impacts to the butterfly and its habitat. Individual butterflies 
(larvae, pupae, and adults), and larval host plants and nectar plants, 
may be crushed during project implementation. In areas where thinned 
trees are chipped (mastication), layers of wood chips may become too 
deep and impact survival of butterfly larvae and pupae, as well as 
larval host plants and nectar plants. Soil and vegetation disturbance 
during project implementation also could result in increases in weeds 
and disturbance-adapted species, such as Chrysothamnus spp. 
(rabbitbrush), and these plants could compete with Mt. Charleston blue 
larval host and nectar plants.
Conservation Agreements and Plans
    A conservation agreement was developed in 1998 to facilitate 
voluntary cooperation among the USFS, the Service, and the State of 
Nevada Department of Conservation and Natural Resources in providing 
long-term protection for the rare and sensitive flora and fauna of the 
Spring Mountains, including the Mt. Charleston blue (Forest Service 
1998, pp. 1-50). Many of the conservation actions described in the 
conservation agreement have been implemented; however, several 
important conservation actions that would have directly benefited the 
Mt. Charleston blue have not been implemented. Regardless, many of the 
conservation actions in the conservation agreement (e.g., inventory and 
monitoring) would not directly reduce threats to the Mt. Charleston 
blue. In 2004, the Service and USFS signed a memorandum of agreement 
that provides a process for review of activities that involve species 
covered under the 1998 Conservation Agreement (Forest Service and 
Service 2004, pp. 1-9). Formal coordination through this memorandum of 
agreement was established to (1) Jointly develop projects that avoid or 
minimize impacts to listed, candidate and proposed species, and species 
under the 1998 conservation agreement; and (2) to ensure consistency 
with commitments and direction provided for in recovery planning 
efforts and in conservation agreement efforts. More than half of the 
past projects that impacted Mt. Charleston blue habitat were reviewed 
by the Service and USFS under this review process, but several were 
not. Some efforts under this memorandum of agreement have been 
successful in reducing or avoiding project impacts to the butterfly, 
while other efforts have not.
    The loss or modification of known occupied and presumed occupied 
butterfly habitat in Upper Lee Canyon, as discussed above, has occurred 
in the past. However, more recently the USFS has suspended decision on 
certain projects that would potentially impact Mt. Charleston blue 
habitat (see discussion of lower parking lot expansion and new 
snowmaking lines projects under Recreation Development Projects, 
above). In addition, the USFS has recently reaffirmed its commitment to 
collaborate with the Service in order to avoid implementation of 
projects or actions that would impact the viability of (Forest Service 
2010c). This commitment includes: (1) Developing a mutually agreeable 
process to review future proposed projects to ensure that 
implementation of these actions will not lead to loss of viability of 
the species; (2) reviewing proposed projects that may pose a threat to 
the continued viability of the species; and (3) jointly developing a 
conservation agreement (strategy) that identifies actions that will be 
taken to ensure the conservation of the species (Forest Service 2010c).
    The Mt. Charleston blue butterfly is a covered species in the 2000 
Clark County Multiple Species Habitat Conservation Plan (MSHCP). The 
Clark County MSHCP identifies two goals for the Mt. Charleston blue: 
(a) ``Maintain stable or increasing population numbers and host and 
larval plant species''; and (b) ``No net unmitigated loss of larval 
host plant or nectar plant species habitat'' (RECON 2000a, Table 2.5, 
pp. 2-154; RECON 2000b, pp. B158-B161). The USFS is one of several 
signatories to the Implementing Agreement for the Clark County MSHCP, 
because many of the activities from the 1998 Conservation Agreement 
were incorporated into the MSHCP. Primarily, activities undertaken by 
USFS focused on conducting surveying and monitoring for butterflies. 
Although some surveying and monitoring occurred through contracts by 
the USFS, Clark County and the Service, a butterfly monitoring plan was 
not fully implemented.
    Recently, the USFS has been implementing the LVSSR Adaptive 
Vegetation Management Plan (Forest Service 2005b, pp. 1-24) to provide 
mitigation for approximately 11 ac (4.45 ha) of impacts to presumed 
occupied butterfly habitat (and other sensitive wildlife and plant 
species habitat) resulting from projects it implemented in 2005 and 
2006. Under the plan, LVSSR will revegetate impacted areas using native 
plant species, including Torrey's milkvetch. However, this program is 
experimental and has experienced difficulties due to the challenges of 
native seed availability and propagation. Under the plan, Torrey's 
milkvetch is being brought into horticultural propagation, and, if 
successful, plants will begin to be planted in 2011-2013. However, 
these efforts are not likely to provide replacement habitat to the Mt. 
Charleston blue for another 5 years (2016-2018), because of the short 
alpine growing season.
Summary of Factor A
    The Mt. Charleston blue is currently known to occur in two 
locations: The South Loop Trail area in upper Kyle Canyon and LVSSR in 
upper Lee Canyon. Habitat loss and modification as a result of fire 
suppression and long-term successional changes in forest structure, 
implementation of recreational development projects and fuels reduction 
projects, and nonnative species are continuing threats to the butterfly 
in Upper Lee Canyon. Since 2000, seven projects have negatively 
impacted presumed occupied habitat for the Mt. Charleston blue. 
Approved and future projects could negatively impact additional 
presumed occupied occurrences of the Mt. Charleston blue in Lee Canyon 
(identified in Table 1). In addition, if proposed future activities 
under a draft Master Development Plan are approved, they could threaten 
the butterfly, as well as its known occupied and presumed occupied 
habitat at LVSSR.
    Because of its small population size, projects that impact even 
relatively small areas of occupied habitat could threaten the long-term 
population viability of Mt. Charleston blue. The continued loss or 
modification of presumed occupied habitat could further impair the 
long-term population viability of the Mt. Charleston blue in upper Lee 
Canyon by removing diapausing larvae (if present) and by reducing the 
ability of the butterfly to disperse during favorable years. The 
successional advance of trees, shrubs, and grasses and the spread of 
nonnative species are continuing threats to the butterfly in upper Lee 
Canyon. The butterfly is presumed extirpated from at least three of the 
six historical locations, likely due to successional changes and the 
introduction of nonnative plants. Nonnative forbs and grasses are a 
threat to the subspecies at LVSSR.
    Although there are agreements and plans that are intended to 
conserve the Mt. Charleston blue and its habitat, to date, some actions 
under these agreements and plans have not been fully implemented. 
Future actions could be implemented in accordance with the terms of 
various agreements and plans; however, this would be voluntary, and

[[Page 12675]]

other factors may preclude the USFS from doing so. Therefore, based on 
the current distribution and recent, existing, and likely future trends 
in habitat loss, we find the Mt. Charleston blue is threatened by the 
present and future destruction, modification, and curtailment of its 
habitat and range.

Factor B: Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Rare butterflies can be highly prized by insect collectors, and 
collection is a known threat to some butterfly species, such as the 
Fender's blue butterfly (65 FR 3882; January 25, 2000). In particular, 
small colonies and populations are at the highest risk. Overcollection 
or repeated handling and marking of females in years of low abundance 
can seriously damage populations through loss of reproductive 
individuals and genetic variability (65 FR 3882; January 25, 2000). 
Given its diminutive size and similarity to closely related subspecies, 
the Mt. Charleston blue is not likely to be of considerable aesthetic 
interest to collectors or the general public.
    We are not aware of any information that indicates the butterflies 
are being sought by collectors or collected for other purposes. 
Therefore, we do not find that overutilization for commercial, 
recreational, scientific, or educational purposes threatens the Mt. 
Charleston blue.

Factor C: Disease or Predation

    We are not aware of any information regarding any impacts from 
either disease or predation on the Mt. Charleston blue. Therefore, we 
do not find that disease or predation threatens the Mt. Charleston 
blue.

Factor D: The Inadequacy of Existing Regulatory Mechanisms

    Existing regulatory mechanisms or other agreements that could 
provide some protection for the Mt. Charleston blue 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 Mt. 
Charleston blue primarily occurs on Federal land under the jurisdiction 
of the USFS; therefore, the discussion below primarily focuses on 
Federal laws.
Local Laws and Ordinances
    We are not aware of any local land use laws or ordinances that have 
been issued by Clark County or other local government entities for 
protection of the Mt. Charleston blue.
State Law
    Nevada Revised Statutes sections 503 and 527 offer protective 
measures to wildlife and plants, but do not include invertebrate 
species such as the Mt. Charleston blue. Therefore, no regulatory 
protection is offered under Nevada State law.
Federal Law
    Mt. Charleston blues have been detected in only two general areas 
in recent years--the South Loop Trail area where adult butterflies were 
recently detected during the summer of 2010 and LVSSR. The South Loop 
Trail area is located along the ridgeline between Griffith Peak and 
Charleston Peak within the Mt. Charleston Wilderness. The U.S. Forest 
Service manages lands designated as wilderness under