[Federal Register Volume 71, Number 152 (Tuesday, August 8, 2006)]
[Proposed Rules]
[Pages 44980-44988]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-12743]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17


Endangered and Threatened Wildlife and Plants; 90-Day Finding on 
a Petition To List the Thorne's Hairstreak Butterfly as Threatened or 
Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding on a petition to list the Thorne's hairstreak butterfly 
(Callophrys [Mitoura] grynea thornei or Callophrys [Mitoura] thornei) 
as an endangered species under the Endangered Species Act of 1973, as 
amended. We find the petition does not provide substantial scientific 
or commercial information indicating the requested action is warranted. 
Therefore, we will not initiate a further status review in response to 
this petition. We ask the public to submit to us any new information 
that becomes available concerning the status of the Thorne's hairstreak 
butterfly or threats to it.

DATES: The finding announced in this document was made on August 8, 
2006.

ADDRESSES: The complete file for this finding is available for public 
inspection, by appointment, during normal business hours at the 
Carlsbad Fish and Wildlife Office, U.S. Fish and Wildlife Service, 6010 
Hidden Valley Road, Carlsbad, CA 92011. New information, materials, 
comments, or questions concerning the Thorne's hairstreak butterfly may 
be submitted to us at any time at the above address.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad 
Fish and Wildlife Office (see ADDRESSES section above), by telephone at 
760-431-9440, or by facsimile to 760-431-9624. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at 800-877-8339, 24 hours a day, 7 
days a week.

SUPPLEMENTARY INFORMATION:

Background

    Section 4(b)(3)(A) of the Endangered Species Act (Act) (16 U.S.C. 
1531 et seq.) requires that we make a finding on whether a petition to 
list, delist, or reclassify a species presents substantial information 
to indicate that the petitioned action may be warranted. To the maximum 
extent practicable, this finding is to be made within 90 days of 
receipt of the petition, and the finding is to be published in the 
Federal Register.
    This finding summarizes information included in the petition and 
information available to us at the time of the petition review. A 90-
day finding under section 4(b)(3)(A) of the Act and Sec.  424.14(b) of 
our regulations is limited to a determination of whether the 
information in the petition meets the ``substantial information'' 
threshold. Substantial information is ``that amount of information that 
would lead a reasonable person to believe that the measure proposed in 
the petition may be warranted'' (50 CFR 424.14(b)).

Previous Federal Action

    The Thorne's hairstreak butterfly was included as a Category 2 
candidate species in our November 21, 1991 (56 FR 58804), and November 
15, 1994 (59 FR 58982), Candidate Notices of Review (CNOR). Category 2 
included taxa for which information in the Service's possession 
indicated that a proposed listing rule was possibly appropriate, but 
for which sufficient data on biological vulnerability and threats were 
not available to support a proposed rule. In the CNOR published on 
February 28, 1996, the Service announced a revised list of plant and 
animal taxa that were regarded as candidates for possible addition to 
the List of Threatened and Endangered Species (61 FR 7595). The revised 
candidate list included only former Category 1 species. All former 
Category 2 species were dropped from the list in order to reduce 
confusion about the conservation status of these species, and to 
clarify that the Service no longer regarded these species as candidates 
for listing. Since the Thorne's hairstreak butterfly was a Category 2 
species, it was no longer recognized as a candidate species as of the 
February 28, 1996, CNOR.
    On June 4, 1991, the Service received a petition dated May 27, 
1991, from David Hogan of the San Diego Biodiversity Project to list 
the Thorne's hairstreak butterfly, Hermes copper butterfly 
(Hermelycaena [Lycaena] hermes), Laguna Mountains skipper (Pyrgus 
ruralis lagunae), and Harbison's dun skipper (Euphyes vestries 
harbinsoni) as endangered under the Act. In a Federal Register notice 
dated July 19, 1993 (58 FR 38549), the Service announced its finding on 
the petition. We found that the petition presented substantial 
information for the Laguna Mountains skipper, but not for the other 
three butterflies. However, the finding also concluded that other 
substantial information existed to support a

[[Page 44981]]

decision that listing may be warranted for the other three butterflies, 
including the Thorne's hairstreak butterfly, and announced our 
intention to continue the formal status review of these species. In a 
proposed rule for the Laguna Mountain skipper and Quino checkerspot 
butterflies published on August 4, 1994 (59 FR 39869), the Service 
clarified that the negative 90-day finding on the Thorne's hairstreak 
butterfly and the other two butterflies ``was made because sufficient 
information was not available regarding the threats to and biological 
vulnerability of these'' butterflies. Though we have continued and will 
continue to collect available data on the Thorne's hairstreak butterfly 
and the other two butterflies, we did not complete the status review of 
Thorne's hairstreak butterfly pursuant to section 4(b)(3)(A) of the 
Act.
    On October 25, 2004, the Service received an updated petition to 
list the Thorne's hairstreak and Hermes copper butterflies as 
endangered from David Hogan of the Center for Biological Diversity. 
Petitioners also sought emergency listing protection for Thorne's 
hairstreak and designation of critical habitat for both butterfly taxa 
concurrent with listing, if warranted. Included in the petition was 
information regarding the subspecies's taxonomy, biology, ecology, 
historical and current distribution, present status, and potential 
causes of decline and imminent threats. In a letter dated May 9, 2005, 
the Service determined that despite apparent threats to Thorne's 
hairstreak butterfly, such threats did not appear to be of a magnitude 
and severity to warrant emergency listing. In our response, we also 
advised the petitioners that we had insufficient funds to respond to 
the petitions at that time. On March 15, 2005, we received a 60-day 
notice of intent to sue filed by the Center for Biological Diversity 
for lack of response to the Thorne's hairstreak and Hermes copper 
butterfly petitions. On October 18, 2005, the Center for Biological 
Diversity filed a complaint for declaratory and injunctive relief 
challenging our failure to make the required 90-day findings on these 
two petitions. The Service agreed to submit 90-day petition findings on 
Thorne's hairstreak and Hermes copper butterflies to the Federal 
Register by August 1, 2006, and if the 90-day findings determined that 
listing may be warranted, to submit 12-month findings to the Federal 
Register by June 1, 2007. This notice constitutes our 90-day finding on 
the petition to list the Thorne's hairstreak butterfly. The 90-day 
finding on the petition to list the Hermes copper butterfly will be 
published in the Federal Register separately.
    In completing this 90-day finding, the Service has reviewed not 
only the information submitted in the petition, but also information in 
our files. This includes all of the data we had obtained prior to the 
July 19, 1993, not substantial finding that would have been considered 
in any internal status reviews had one been completed, as well as all 
of the information we have continued to collect on this species to 
date. Based on all new information and our analysis below, we have 
determined that the petition does not present substantial scientific or 
commercial information indicating that listing the Thorne's hairstreak 
butterfly may be warranted or that a status review or status assessment 
should be conducted.

Taxonomy

    Thorne's hairstreak butterfly (Mitoura thornei) was originally 
described by John Brown (1983) based on a specimen collected by Fred 
Thorne in 1972, near Lower Otay Lake, which is generally west of Otay 
Mountain. Brown distinguished M. thornei from its closest relative M. 
loki on the basis of host preference (cypress (Cupressus) versus 
juniper (Juniperus)), the color of the ventral hindwing surface (green 
versus purple), and geographical isolation.
    Brown (1983) described Thorne's hairstreak butterfly at the species 
rank, which has been accepted by many subsequent authors (Garth and 
Tilden 1986; Ballmer and Pratt 1988; Emmel et al. 1998; Opler and 
Warren 2004). However, some authors disagree with this classification. 
Shields (1984) considers Thorne's hairstreak butterfly a subspecies of 
M. loki, and Scott (1986) lists it as a subspecies of the Cedar 
hairstreak (Callophrys gryneus). The issue of the taxonomic ranking and 
placement of Thorne's hairstreak butterfly was considered by the 
Committee on Scientific Names of North American Butterflies in 1999. 
The committee adopted the recommendation made by Dr. Robert K. Robbins, 
an expert on Lycaenidae (Research Entomologist with U.S. Department of 
Agriculture's Systematic Entomology Laboratory at the National Museum 
of Natural History, Smithsonian Institution), that both M. loki and M. 
thornei should be treated as belonging to the superspecies, C. gryneus 
(Faulkner and Klein 2005). Currently, the committee's Checklist of 
North American Butterflies (North American Butterfly Association (NABA) 
2004) includes M. thornei and M. loki as Callophrys gryneus thornei and 
Callophrys gryneus loki, respectively.
    The petitioner deferred to other experts regarding the appropriate 
classification, taxonomic rank, of Thorne's hairstreak butterfly (i.e., 
species or subspecies). In 2004, the Service contracted with Dr. 
Richard W. Van Buskirk (Pacific University in Forest Grove, Oregon) to 
review the taxonomic status of Thorne's hairstreak butterfly. Following 
Van Buskirk's recommendation (Van Buskirk 2004), the Service recognizes 
Thorne's hairstreak butterfly as the subspecies Callophrys gryneus 
thornei.

Description

    Adult Thorne's hairstreak butterflies are approximately 1.0 to 1.2 
inches in wingspan (25.4 to 30.5 millimeters) (Brown 1983). The 
forewings and hindwings are rich reddish brown with dark brown shading 
on the margin. The ventral surface forewing is mahogany brown with 
traces of lavender overscaling. The males bear well-developed scent 
pads on the forewings, and the hindwings are tailed. Eggs are round 
(echinoid), light green, and laid singly on the food plant. Garth and 
Tilden (1986) provide a description of the butterfly's early stages.
    The Thorne's hairstreak butterfly is bivoltine (has two flight 
periods per year) and overwinters in the pupal stage. The pupation time 
for first generation is about 10 to 15 days, with emergence occurring 
in late February through March or possibly early April, depending on 
rainfall. The second generation emerges in June. A third brood may take 
place in September if summer rains occur (Faulkner and Klein 2005).
    Eggs incubate in 7 to 14 days. The first instar larvae initially 
bore into the young stems of the host plant, Tecate cypress (Cupressus 
forbesii), but later become external feeders. Pupation is in the duff 
and leaf litter at the base of the host plant, and larvae feed on young 
cypress stems. Mature larvae are vivid green with two irregular white 
crescents on each segment, forming a longitudinal white stripe along 
each side of the larvae (Faulkner and Klein 2005).
    Conifer-eating larvae within family Lycaenidae are an unusual 
occurrence. Within San Diego County, its congeners Callophrys gryneus 
loki (juniper hairstreak) and Callophrys nelsoni (Nelson's hairstreak) 
have only been found in association with California juniper (Juniperus 
californica) and incense cedar (Calocedrus decurrens) host plants, 
respectively (Faulkner and Klein 2005).

[[Page 44982]]

Habitat

    According to Brown (1983), Thorne's hairstreak butterfly is 
restricted to its larval host plant, Tecate cypress. Associated with 
chaparral ecosystems in southern California and northern Baja 
California, Tecate cypress occurs primarily on north-facing slopes from 
near sea level to over 4,200 feet (ft) (1,300 meters (m)) in elevation 
(Dunn 1986). Although some experts hypothesized that larvae eat only 
mature Tecate cypress at least 25 to 30 years old (Klein and Williams 
2003; Faulkner and Klein 2005), recent post-fire observations of adults 
in three stands of cypress trees less than 9 years old within a 1996 
fire footprint (Faulkner and Klein 2005) do not support that 
hypothesis. Thus, the best available information indicates Thorne's 
hairstreak butterflies can use host plants as young as 9 years of age.
    Adult Thorne's hairstreak butterflies are known to nectar on 
Eriogonum fasciculatum (California buckwheat), Ceanothus tomentosus 
(Ramona lilac), and Lotus scoparius (deerweed), in the vicinity of 
Tecate cypress stands (Faulkner and Klein 2005).
    Thorne's hairstreak butterfly dispersal behavior is not well known. 
An individual was observed nectaring on deerweed plants 0.25 miles (mi) 
(0.4 kilometer (km)) away from the nearest Tecate cypress (Faulkner and 
Klein 2005). Adults have been observed nectaring on California 
buckwheat as much as 197 ft (60 m) away from Tecate cypress trees 
(Faulkner and Klein 2005). Mattoni (1998) gave estimated relative 
movement values for three species of Callophrys butterflies in the 
greater Los Angeles area. Two species were estimated to move between 
330-3300 ft (100-1000 m), and one from 3300 ft to 30 mi (1-50 km). 
Among butterflies, the genus Callophrys appears to be relatively 
sedentary.

Historical and Current Range/Distribution

    Thorne's hairstreak butterfly is known only from the vicinity of 
Otay Mountain in southern San Diego County, California, in association 
with its larval host plant, Tecate cypress. Though not common within 
the limits of its range, Tecate cypress occurs in widely scattered and 
isolated ``floristic islands'' in the chaparral of southern California 
and Baja California Norte (Griffin and Critchfield 1972; Dunn 1986; 
Minnich 1987). In California, Tecate cypress is found on Guatay 
Mountain, Otay Mountain, and Tecate Peak in San Diego County; and on 
Sierra Peak and in Coal Canyon in Orange County (Dunn 1986).
    Historically, the Thorne's hairstreak butterfly has been reported 
on Otay Mountain in San Diego County, primarily in Little Cedar Canyon 
and Cedar Canyon (Klein and Williams 2003). An unconfirmed historic 
observation of the subspecies in Orange County on private land has been 
reported (R. Stanford pers. comm. in Faulkner and Klein 2005). 
Multiple, consecutive surveys over 10 years within areas containing 
Tecate cypress on Tecate Peak and Guatay Mountain in San Diego County 
and some stands in Baja California, Mexico, conducted annually during 
the late 1980s and early 1990s, did not yield any Thorne's hairstreak 
butterflies (Anderson 2003). However, we do not have documentation of 
these surveys and are unable to determine what proportion of the Tecate 
cypress stands on Tecate Peak and Guatay Mountain in San Diego County 
were surveyed. Therefore, it is unclear whether these surveys efforts 
constitute comprehensive surveys of the Tecate cypress stands in these 
areas. Limited sampling in the Sierra Peak-Coal Canyon area in Orange 
County did not yield any Thorne's hairstreak butterfly observations 
(Brown 1983).
    More than 20 groves of Tecate cypress are documented by botanical 
collections or aerial imagery from Baja California Norte, Mexico, 
indicating potential distribution of the Thorne's hairstreak butterfly 
in Mexico. Minnich (1987) described the northernmost stands of Tecate 
cypress in Mexico as extensions of U.S. populations at the border. As 
stated above, some surveys have been conducted in Tecate cypress stands 
in Baja California, Mexico for Thorne's hairstreak butterflies during 
the late 1980's and early 1990's. However, since we do not have 
documentation of these surveys, it is unclear what proportion of the 
Tecate cypress stands in Baja were surveyed. Therefore, more 
investigation is required to determine the possible extent of 
undiscovered populations of Thorne's hairstreak butterfly in Tecate 
cypress stands in Mexico.

Population Estimates/Status

    No specific data on Thorne's hairstreak butterfly abundance or 
population dynamics and distribution exists, although a number of 
apparently discrete occupied locations have been identified. The 
petition states that fewer than 10 historically occupied locations have 
been identified on Otay Mountain (Klein and Williams 2003) primarily 
within designated wilderness administered by the Bureau of Land 
Management (BLM). The status of Thorne's hairstreak butterfly and its 
habitat (areas dominated by Tecate cypress over 6 ft (2 m) tall) was 
evaluated as part of a post-2003 Otay/Mine fire reassessment of species 
covered by the section 10(a)(1)(B) permit associated with the San Diego 
Multiple Species Conservation Plan (MSCP). Surveys of Tecate cypress 
stands conducted in 2004 revealed the presence of 4 to 5 areas occupied 
by the subspecies (Martin 2004; Klein 2006). However, Martin (2004) and 
Klein (2006) acknowledge that not all cypress stands were surveyed due 
to accessibility. No quantitative data on population size exist.

Threats Analysis

    In the following discussion, we respond to each of the major 
assertions made in the petition, organized by the Act's listing 
factors. Section 4 of the Act and its implementing regulations (50 CFR 
424) set forth the procedures for adding species to the Federal list of 
endangered and threatened species. A species may be determined to be 
endangered or threatened due to one or more of the five factors 
described in section 4(a)(1) of the Act. The five listing factors are: 
(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; and 
(E) other natural or manmade factors affecting its continued existence.
    This 90-day finding is not a status assessment and does not 
constitute a status review under the Act. A brief discussion of how 
each of the five listing factors applies to the Thorne's hairstreak 
butterfly follows.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Habitat or Range

    The petition, its appendices, and referenced documents discuss the 
following threats that we have grouped under Factor A: wildfire, 
prescribed fire, grazing, and vehicle access and recreation.
Wildfire
    Information provided by the petitioner. The petitioner asserts that 
Thorne's hairstreak butterfly is highly and immediately vulnerable to 
extinction due to the threat of wildfire as a result of direct 
mortality of individuals and indirect mortality due to loss of the 
subspecies' larval host plant, Tecate cypress. (The threat of wildfire 
as it relates to direct mortality of individual butterflies is 
discussed under Factor E.) They assert that one

[[Page 44983]]

single new fire could cause the extinction of this butterfly. The 2003 
Otay/Mine fire served as an example of the threat of fire to the 
butterfly when it burned 68 percent of the Thorne's hairstreak 
butterfly habitat (Betzler et al. 2003). The petitioner claims the 
number of fires greatly exceeds natural fire frequencies in southern 
California's chaparral ecosystems, and the excessive fires have reduced 
stands of mature Tecate cypress utilized by Thorne's hairstreak 
butterflies.
    The petitioner provided a map illustrating multiple fires that have 
burned through and near Thorne's hairstreak butterfly locations within 
the last century. According to the petition, increased human 
populations and utilization of wildlands correlates with increased 
southern California wildfire frequency (Keeley et al. 1999; Keeley 2001 
[document not submitted with petition]; Keeley and Fotheringham 2003; 
Wells et al. 2004).
    The petitioner cited two references, Brooks et al. (2002 [correct 
citation 2004]) and Keeley and Fotheringham (2003), which provide 
examples where excessive fire harms chaparral ecosystems and dependent 
species in a number of ways. The petition quoted Keeley and 
Fotheringham (2003), ``* * * ecosystem health of shrublands is 
threatened not by lack of fire but by high fire frequencies that exceed 
the resilience of many species.'' The petitioner claims that excessive 
fire contributes to expansion of highly flammable, invasive, alien 
grasses (D'Antonio and Vitousek 1992) and forbs, contributing in turn 
to an even greater fire frequency. Excessively frequent fire (more than 
once a decade) may prevent nonsprouting chaparral shrubs from reaching 
maturity, thereby eliminating these species entirely from the system 
(Keeley and Fotheringham 2003).
    According to the petitioners, frequent fire also leads to type 
conversion and replacement of chaparral ecosystems with alien plant 
species (Keeley 2001; Keeley and Fotheringham 2003). The petitioner 
asserted that fire-induced conversion of Tecate cypress and surrounding 
chaparral to vegetation dominated by invasive plant species reduces 
Thorne's hairstreak butterfly habitat through loss of host and nectar 
plants. Moreover, the petitioner reported that Zedler et al. (1983) 
documented vegetation conversion in the San Ysidro Mountains within 1 
mi of Thorne's hairstreak butterfly populations. Based on a personal 
communication with Michael Klein, a Thorne's hairstreak butterfly 
expert, the petitioner also refers to anecdotal observations that 
exotic grasses and forbs appear to be increasing in former Tecate 
cypress habitat following the 2003 fire.
    Analysis of the information provided in the petition and available 
to us at the time of petition review. Though cypress trees do not 
survive fire, fire is integral to initiating cone opening and seed 
dispersal and is, therefore, critical for successful regeneration of 
Tecate cypress stands (Zedler 1977; Dunn 1986). Cone production begins 
as early as 5 to 7 years of age, but is sporadic until the trees reach 
about 30 years of age, and maximum cone production may not be achieved 
until 50 years or later (Zedler 1981; Dunn 1986). For cypress 
population levels to be maintained, the interval between fires must be 
long enough to permit enough trees to produce sufficient cones and 
seeds to replace the trees consumed in the fire. Zedler (1981) noted 
that if [all] stands of Tecate cypress were burned every 33 years, his 
``data suggest that near extinction would result after three or four 
fires. Cone and seed production depend on factors other than age alone 
and a large variation in average tree size and hence cone production 
exists within stands.''
    Faulkner and Klein (2005) agreed with Brown (1993) who stated that, 
``[c]haparral fires probably represent the greatest threat to * * * 
[Tecate cypress] and its associated insect fauna, including Thorne's 
hairstreak butterfly.'' Though human-induced ignitions have been a part 
of the California landscape for more than 10,000 years, humans ``likely 
have had a greater influence in the twentieth century due to the near 
exponential rise in population density and fire frequency in the 
southern part of the state'' (Keeley and Fotheringham 2003). The 
frequency of smaller fires proximal to the Mexican Border may have 
increased on Otay Mountain, and, as the petitioner claims, this may be 
due to increasing ignition by illegal immigrants and associated border 
patrol activities since the 1990s (Jacob 1999, California Department of 
Forestry and Fire prevention (CDF) 2006). For example, in 2004, over 
100 fires were reported on Otay Mountain (Woychak 2006). However, the 
majority of these fires were relatively small and localized (Porter 
2006) and only affected small percentages of areas likely to be 
Thorne's hairstreak habitat patches associated with Tecate cypress.
    The majority of the studies examining the impacts of fire frequency 
on California plant communities have focused primarily on overall 
impacts to dominant vegetative types, such as coastal sage scrub, 
chaparral, hardwood conifer forest, conifer forest, shrublands, and 
desert shrublands (Zedler 1981; Zedler et al. 1983; Keeley et al. 1999; 
Keeley and Fotheringham 2003; Wells et al. 2004). In a GIS modeling 
study, Wells et al. (2004) largely concurred with Keeley et al (1999) 
that increasing human population (especially at lower elevations) has 
resulted in a greater number of fires and an increase in area burned 
overall in Southern California. However, looking at fire frequency for 
chaparral in San Diego County specifically, Wells et al. (2004) 
concluded that the ``trend in burning in chaparral is virtually flat 
over the past century, and if the years following 1950 are considered, 
there has been a marked decrease in area burned since then.''
    Few studies have examined the association between fire frequency 
and population dynamics of Tecate cypress specifically. Dunn (1985, 
1986) concluded at the time of his work in the 1980s that the Tecate 
cypress population on Otay Mountain, the largest population in 
California (about 5,900 acres (2,400 hectares)), was ``in no immediate 
danger'' and that ``a fire would do little damage'' because the 
majority of the trees were over 40 years old and the threat of fire 
associated with the human interface was relatively low. In fact, Dunn 
(1984) had concluded in his Master's thesis that, at that time, no need 
existed for strict fire exclusion on Otay Mountain. As stated above, 
increasing human population has resulted in a greater number of fires 
in California. However, while portions of the Tecate cypress stands on 
Otay Mountain were burned in 1996 and again in the 2003, no recent data 
exist documenting the actual extent of impact to Tecate cypress 
specifically. Although Zedler and others (1983) documented a decline in 
native shrub abundance with the introduction of annual ryegrass (Lolium 
multiflorum) following two fires in 1979 and 1980 on Otay Mountain 
(i.e., the petitioner's claim of type conversion in the San Ysidro 
Mountains within 1 mi of Thorne's hairstreak butterfly populations), 
this work did not involve Tecate cypress and is not applicable to the 
species. Moreover, in a recent study of the fire frequency and 
population trend in four Tecate cypress populations in California, 
cited on page 9 of the petition (cited as ``Ansary in print ''), de 
Gouvenain and Ansary (in press) reported that the Otay Mountain, Tecate 
Peak, and Guatay populations ``appeared to be stable or potentially 
increasing'' (i.e., the rate of population increase or [lgr] > 1), 
while only the Coal Canyon/Sierra Peak population in Orange County 
``appeared to be

[[Page 44984]]

declining'' due to a shorter fire interval at that site.
    We used GIS data in our files to overlay Tecate cypress 
distribution on the petition map illustrating multiple fires that have 
burned through and near Thorne's hairstreak butterfly locations within 
the last century, and determined the majority of Tecate cypress was 
within one or two fire footprints during the 93 year period from 1910 
to 2003. Therefore, information in our files does not support the claim 
that the fire frequency is high relative to Tecate cypress reproductive 
maturity.
    As cited in the petition, 68 percent of the Thorne's hairstreak 
butterfly habitat (Tecate cypress) burned during the 2003 Otay/Mine 
fire, a reduction from 5,577 ac (2,257 ha) to 1,778 ac (720 ha) 
according to preliminary estimates by Betzler et al. (2003). 
Nonetheless, butterfly occupation was documented after the 2003 fire in 
2004 and 2005, mostly on the southwest slope of the mountain within the 
1996 burn area that did not burn in 2003 (Martin 2004; Faulkner and 
Klein 2005; Klein 2006). While the fire footprint was estimated by 
Betzler et al. (2003) to have covered 68 percent of the Tecate cypress 
habitat on Otay Mountain, the amount of Tecate cypress that actually 
burned is likely less. The source cited by Betzler et al. (2003) was a 
report prepared by the Interagency Burned Area Emergency Response Team 
(IBAERT 2003), which gives vegetation mortality estimates in categories 
of 0 to 25 percent, 26 to 75 percent, and greater than 76 percent. It 
is not clear how Betzler et. al. (2003) calculated the 68 percent 
burned habitat area, however it could have been based on the percent of 
mapped Tecate cypress distribution within those burn categories given 
by IBAERT (2003); therefore, Betzler et al. (2003) may not have known 
how much Tecate cypress within the fire footprint was actually killed.
    Limited post-fire monitoring in 2004 revealed the presence of at 
least five unburned stands of mature Tecate cypress (defined for the 
survey as a patch of at least 50 trees greater than 2 meters tall), 
four of which were determined to be occupied by adult Thorne's 
hairstreak butterflies at the time of the survey (Martin 2004). Two 
areas adjacent to or within canyons known to contain Tecate cypress 
were not surveyed in 2004. At least one area, the lower portion of 
O'Neal Canyon may contain a significant stand since the upper portion 
supports the largest stand of extant cypress (Martin 2004). According 
to Martin (2004), these five stands constituted approximately 166 ac 
(36 ha). However, since he was not able to survey all potential habitat 
areas and his analysis was limited to stands of at least 50 mature 
trees, additional stands and stands of less than 50 mature and immature 
trees may have persisted after the fire.
    Also, de Gouvenain and Ansary (in press) hypothesize that the steep 
north-facing slopes and rocky outcrops where Tecate cypress is found 
may function as refugia for Tecate cypress during fire events in the 
surrounding chaparral habitat. A comprehensive survey of Tecate cypress 
on Otay Mountain is needed in order to accurately determine the extent 
of the impact caused by the 2003 fire and to what extent the Thorne's 
hairstreak butterfly is utilizing the remaining Tecate cypress habitat 
(at least 3,799 ac (1,537 ha)).
    With regard to curtailment of habitat and range by fire, it is 
important to consider that Thorne's hairstreak habitat distribution on 
Otay Mountain is slightly greater than that of its larval host plant 
(Tecate cypress), and must be based on adult resource use and movement 
between and on the periphery of host plant stands. Given the 
evolutionary relationship of Thorne's hairstreak and Tecate cypress 
with fire, it is likely burned areas devoid of woody vegetation and 
reduced butterfly population density after fire facilitate movement 
between unburned host plant patches. For example, in a mark-recapture 
study of Parnassius smintheus (Papilionidae) butterflies, Roland et al. 
(2000) concluded ``butterflies move readily through open meadow but 
that forests are twice as resistant to butterfly movement. Butterflies 
also tended to stay at sites with high numbers of butterflies, but 
readily emigrate from sites with small populations.'' Roland et al.'s 
(2000) results are a good example of how differences in habitat 
structure and population density can affect butterfly movement. 
Differences in population densities and habitat structure are known to 
commonly affect movement patterns of butterflies (Ries and Debinski 
2001; Service 2003).
    Along with the direct loss of Tecate cypress, the Thorne's 
hairstreak butterfly's host plant, the petitioners claim that increased 
fire frequency results in the conversion of Tecate cypress and 
surrounding chaparral to vegetation dominated by invasive plant 
species, further reducing the amount of host and nectar plants. As 
discussed above, it appears that Tecate cypress populations on Otay 
Mountain are stable and potentially increasing overall and that 
frequency of fire in chaparral communities in San Diego County over the 
past century is stable or potentially decreasing overall. Also, 
although Zedler et al. (1983) documented a decline in native shrub 
abundance following two fires in 1979 and 1980 on Otay Mountain, they 
state that changes to the vegetative community following the 1979 fire 
alone are similar to those commonly seen in chaparral fires. Their 
study was not conducted in an area occupied by Tecate cypress. The 
common pattern after chaparral fires is for native and introduced 
annual herbs to dominate for the 1st year and then gradually decline as 
the cover of shrub and subshrubs increases (Zedler et al. (1983). They 
reported drastic reductions in several chaparral species, particularly 
those with limited dispersal and specialized germination requirements, 
after the same area that burned in 1979 burned again in 1980. However, 
they state that over time, it is likely that coastal sage scrub 
species, particularly those that are vigorous invaders of man-made and 
natural disturbance, including Eriogonum fasciculatum, a nectar source 
for Thorne's hairstreak butterfly, are likely to reoccupy the area. 
Therefore, it is likely that while the vegetative community may undergo 
short-term conversion, over time, native, fire adapted species will 
reestablish.
    In sum, information in the petition and available to us does not 
substantiate a recent decline or downward trend in the extent of Tecate 
cypress on Otay Mountain, the host plant of the Thorne's hairstreak 
butterfly, as a result of increased fire frequency and associated alien 
plant invasion.
Prescribed Fire
    Information provided in the petition. The petitioner states that 
while prescribed fire does not appear to be planned for the San Ysidro 
Mountains, it could compound the threat of excessive fire to Thorne's 
hairstreak butterflies and Tecate cypress if implemented in the future.
    Analysis of information provided in the petition and available to 
us at the time of petition review. No evidence exists to support the 
petitioner's claim that prescribed burning would be allowed within the 
Otay Mountain Wilderness. The current BLM policy is 100 percent fire 
suppression on Otay Mountain (Woychak 2006).
Grazing
    Information provided in the petition. The petitioner stated that 
BLM authorizes grazing on Otay Mountain in an area occupied by Thorne's 
hairstreak butterfly prior to the 2003 Otay/Mine fire and near the 
``last five known remaining populations.'' The allotment is now vacant 
according to agency staff,

[[Page 44985]]

but BLM is actively considering renewal of this grazing lease, 
according to a Notice of Proposed Action dated May 26, 2004.
    The petitioner claimed that renewal of the Otay Mountain grazing 
allotment lease would result in significant direct and indirect effects 
similar to those identified by the Service for the Quino checkerspot 
butterfly (January 16, 1997; 62 FR 2313). The Quino checkerspot 
butterfly recovery plan (Service 2003) noted that grazing may harm the 
butterfly through destruction of larval host plants, soil compaction, 
degradation of cryptogamic soil crusts, and trampling of eggs and 
larvae. The invasion of alien plants may be facilitated by degradation 
of soil crusts. The recovery plan recommends phasing out of commercial 
grazing in Quino checkerspot butterfly's habitat.
    The petitioner also stated that grazing on the Otay Mountain 
allotment could harm the Thorne's hairstreak butterfly and Tecate 
cypress even if grazing is excluded around existing populations of 
these species because grazing could lead to the introduction of 
invasive alien plants. These plants could increase fire frequency, 
resulting in the loss of populations of sensitive species and habitat 
degradation, and may result in subsequent further expansion of alien 
plants through additional disturbance from fire.
    Analysis of information provided in the petition and available to 
us at the time of petition review. We confirmed that an active 5,522 
acre (2,235 ha) BLM grazing allotment exists on Otay Mountain (Doran 
2006) that overlaps occupied Thorne's hairstreak butterfly habitat. 
Approximately one-third of Tecate cypress woodland on the mountain 
(2,026 acres (820 ha)) occurs within the Otay Mountain Grazing 
Allotment on the north side of the mountain (Anderson and Love 2006). 
Approximately half (20 acres (8 ha)) of a patch of occupied mature 
Tecate cypress trees was confirmed to be within the southern grazing 
allotment boundary in 2004 (Anderson and Love 2006). However, the 
grazing allotment is in a non-use status, which means that the allottee 
does not intend to graze in the near term, and grazing is not allowed 
in the Cedar Canyon Area of Critical Environmental Concern (Doran 
2006). Also, Tecate cypress woodland would not often be very accessible 
to cattle within the allotment, because of the extremely steep, thickly 
vegetated terrain associated with Tecate cypress stands.
    We were unable to confirm the petitioner's assertion that the 
renewal of the grazing allotment lease will likely result in 
significant direct and indirect harm to Thorne's hairstreak butterflies 
and Tecate cypress populations. The petitioner failed to provide 
specific examples of negative impacts from grazing on Thorne's 
hairstreak butterflies and Tecate cypress. Comparison to Quino 
checkerspot butterfly grazing threats is not appropriate because host 
plants for that subspecies, unlike Tecate cypress, are herbaceous 
annuals directly affected by grazing and type-conversion of open-canopy 
vegetation.
Vehicle Access and Recreation
    Information provided by the petitioner. The petitioner claims BLM's 
emphasis on recreation in the San Ysidro Mountains, and maintenance of 
vehicle access likely increases the risk of new fires. BLM lands 
occupied by the subspecies are located within the agency's designated 
Otay Mountain Wilderness. Roads grandfathered into the wilderness 
designation generally allow unrestricted public access in close 
proximity to Thorne's hairstreak butterfly populations except during 
special closures.
    Analysis of information provided in the petition and available to 
us at the time of petition review. Although public access is allowed, 
the Otay Mountain Wilderness is remote, and few people visit the 
wilderness area. Because of the proximity of the wilderness area to the 
United States-Mexico international border, border operations (e.g., 
surveillance and patrolling) are common throughout the wilderness. 
Traffic is concentrated on few main roads adjacent to occupied Thorne's 
hairstreak butterfly habitat. Border patrol vehicles and vehicles 
accessing the wilderness may increase the risk of new fires; however, 
fires that are potentially started by the border patrol would be 
reported immediately. Since access by the public is rare, and border 
patrol vehicle ignitions would be reported, we believe vehicle access 
and recreation is not a significant threat to the subspecies. The 
petitioner neglected to provide specific examples of vehicle access and 
recreation increasing the risk of new fires to Thorne's hairstreak 
butterfly habitat (i.e., Tecate cypress stands), and we are unaware of 
any documentation that directly links vehicles and recreation as a 
threat to this subspecies.
    Because there is no clear threat of fire to Tecate cypress or 
Thorne's hairstreak butterfly, and grazing and recreation impacts 
appear negligible, we conclude that the petition and other available 
information does not constitute substantial scientific information 
indicating listing Thorne's hairstreak butterfly may be warranted due 
to Factor A (destruction, modification, or curtailment of habitat or 
range).

B. The Overutilization for Commercial, Sporting, Scientific, or 
Education Purposes

    The petitioner did not provide information with respect to Factor 
B. We have no information regarding the overutilization for commercial, 
sporting, scientific, or education purposes for Thorne's hairstreak 
butterfly.

C. Disease or Predation

    The petitioner did not provide any information with respect to 
disease nor do we have any information regarding impacts of disease on 
Thorne's hairstreak butterfly.
Predation
    Information provided in the petition. The petitioner stated that 
experts suspect birds, predatory insects, parasitic insects, and 
spiders prey upon the Thorne's hairstreak butterfly. Birds may prey on 
either larvae or adults. The harmful effects of otherwise normal 
predation or parasitism might be exacerbated by population reduction 
from excessive fires.
    Analysis of information provided in the petition and available to 
us at the time of petition review. The petitioner did not provide 
specific information, nor was there any information available in our 
files, documenting that the Thorne's hairstreak butterfly may be 
endangered by predation.

D. The Inadequacy of Existing Regulatory Mechanisms

    The petition and referenced documents discuss three regulatory 
mechanisms that may provide some Thorne's hairstreak butterfly 
conservation, including (1) the Wilderness Act, (2) BLM activities, and 
(3) the San Diego Multiple Species Conservation Plan (MSCP).
Wilderness Act and BLM Activities
    Information provided by the petition. While the petition 
acknowledged BLM lands occupied by the subspecies are protected from 
urban development and mining by the nature of the location within the 
Otay Mountain Wilderness Area (designated under the Wilderness Act), 
the petitioner asserted this area is not intensely managed, and BLM 
does not implement proactive conservation measures for either the 
Thorne's hairstreak butterfly or Tecate cypress. In addition, the 
petitioner maintained that BLM does not recognize the Thorne's 
hairstreak butterfly as a ``sensitive

[[Page 44986]]

[sub]species.'' The petitioner further claims Thorne's hairstreak 
butterfly populations face an additional, unique risk of excessive fire 
as U.S. border enforcement has inadvertently directed illegal Mexican 
immigrant crossings away from coastal urban areas toward wildland areas 
east of Otay Mesa. The petitioner contends that fire and land 
management agencies often identify illegal immigrant's campfires and 
arson as the cause of border-area wildfires.
    Analysis of information provided in the petition and available to 
us at the time of petition review. Congress formally designated BLM 
lands on Otay Mountain as the Otay Mountain Wilderness in 1999 (Otay 
Mountain Wilderness Act, December 11, 1999). The inclusion of these 
occupied habitats within a designated Wilderness provided additional 
significant protection for this area and complemented BLM's objective 
to manage these public lands to provide protection and enhancement for 
biological values. The Wilderness Act of 1964 (16 U.S.C. 1131) 
restricts vehicles, new developments, chainsaws, mountain bikes, 
leasing, and mining from the wilderness area.
    As cited in the petition, BLM's South Coast Resource Management 
Plan guides management and protection on sensitive species and their 
habitat. At the time of the petition, BLM did not recognize Thorne's 
hairstreak as a ``sensitive'' subspecies; however, the subspecies was 
recently officially designated as ``sensitive,'' elevating it to a 
higher management priority level (Schlachter 2006).
    As stated in the petition, no formal plans to specifically manage 
or monitor for Thorne's hairstreak butterfly currently exist. Thorne's 
hairstreak butterfly populations may face an additional, unique risk of 
excessive fire due to activities related to illegal Mexican immigrant 
crossings east of Otay Mesa (Jacob 1999, CDF 2006). However, since at 
this time it appears the primary source of the wildfire threat to the 
subspecies is accidental wildfire caused by illegal immigrants, and 
border security is currently greater than before to prevent illegal 
immigration, fire prevention is indirectly maximized by border patrol 
activities. Fire prevention measures include formation of the Border 
Agency Fire Council, (BAFC) a multi-agency council formed due to the 
wildfire threat to human life and the environment (Jacob 1999). The 
goals of the BAFC are to make people in the border area aware of the 
dangers of wildfire and encourage them to be careful with fire; 
preferably not to start any campfires, but if they do, to understand 
the fire must be completely out before they abandon it (CDF 2006). BAFC 
member agencies represent a collaborative effort to prepare the area 
for fire fighting purposes, including establishment of three helispots 
and construction of spur roads (BAFC 2006). Signs in Spanish posted 
across the mountain warn of the danger of starting campfires and advise 
against it. Also, BLM's current policy is 100 percent fire suppression 
on Otay Mountain (Woychak 2006). Therefore, while a formal management 
plan would benefit the subspecies to guide long-term monitoring and 
other types of conservation actions, it would not necessarily change 
current fire prevention and suppression policies and activities.
San Diego MSCP
    Information in the petition. The petitioner stated that the 
Thorne's hairstreak butterfly is recognized as a ``covered species'' 
under the MSCP and some conservation activities in the San Ysidro 
Mountains occur, but these activities do not appear to have reduced the 
primary threats to the subspecies, especially from excessive wildfire.
    Analysis of information provided in the petition and available to 
us at the time of petition review. Thorne's hairstreak butterfly is 
covered under the MSCP, and the MSCP recognizes that ``a fire 
management program would be needed for prevention of catastrophic fires 
and long term viability of its host plant.'' No fire management plan 
has been written to date, nor has BLM developed a long-term management 
or monitoring plan for the butterfly (J. Schlachter 2006). However, the 
current BLM policy is 100 percent fire suppression on Otay Mountain; 
BLM has received allocations to complete a wilderness management plan; 
and a fire management plan is expected to be completed after the 
wilderness plan and will focus on complete fuel suppression (Woychak 
2006).
    The Service considers the current BLM activities and policies, and 
the MSCP adequate for protection of the subspecies. If the MSCP or 
referenced activities and polices are modified in the future, the 
adequacy of these measures to protect the Thorne's hairstreak butterfly 
should be evaluated at that time. The Service does not believe the 
absence of the cited plans poses a substantial threat such that the 
Thorne's hairstreak butterfly requires additional regulatory mechanisms 
to be developed. Therefore, the petition and other information in our 
files does not present substantial information that the subspecies is 
threatened at this time by the inadequacy of existing regulatory 
mechanisms across all or a significant portion of its range.

E. Other Natural or Manmade Factors Affecting the Continued Existence

    The petition, its appendices, and referenced documents discuss the 
following threats that we have grouped under Factor E: wildfire, 
habitat fragmentation, vulnerability of small and isolated populations, 
and global climate change.
Wildfire
    Information provided in the petition. The petitioner stated the 
Thorne's hairstreak butterfly cannot escape fire. Pupae and larvae are 
likely killed when fire burns Tecate cypress stands and nearby 
chaparral. Adults are also likely killed by fire, due to their habit of 
remaining close to their host plant, and the likelihood of their escape 
being outpaced by an approaching fire. The petition claims excessive 
fires over the last several decades have reduced Thorne's hairstreak 
butterfly population numbers and disrupted metapopulation dynamics and 
stability.
    Analysis of information provided in the petition and available to 
us at the time of petition review. The persistence of the Thorne's 
hairstreak butterfly was considered questionable after the 2003 Otay/
Mine fire, since the fire footprint appeared to cover all areas known 
to be occupied by the subspecies (Anderson 2003; Klein and Williams 
2003). However, adult Thorne's hairstreak butterflies were documented 
from four Tecate cypress stands after the 2003 fire on the southwest 
slope of the mountain (Martin 2004; Faulkner and Klein 2005; Klein). 
Therefore, as discussed under Factor A, it appears that some Tecate 
cypress habitat did not burn during that fire and that the actual 
extent of occupied habitat on Otay Mountain has not yet been 
determined. The petition included a map delineating large fire 
footprints from 1910 to 2003. We used GIS data in our files to overlay 
all known occupancy records on the fire map and determined that 9 out 
of the 12 Thorne's hairstreak butterfly observations (point data) and 
the majority of Tecate cypress distribution are within one or two fire 
footprints during the 93 year period from 1910 to 2003. The apparent 
ability of Thorne's hairstreak butterflies to recolonize immature 
Tecate cypress stands less than 9 years post-fire (Martin 2004; 
Faulkner and Klein 2005; Klein), compared to the relatively low large-
fire frequency indicated by the petition map of less than 2 fires per 
93 years, contradicts petition claims of a direct

[[Page 44987]]

mortality extinction threat due to high fire frequency on Otay 
Mountain. Also, as discussed under Factor A, the steep canyons where 
Tecate cypress is found may provide refugia during a fire.
    While immature Thorne's hairstreak butterflies have not been 
reported from younger stands surveyed after fire, this may be 
attributed to the fact that they are small and cryptic, making them 
difficult to detect, and spend most of their larval stage (early 
instars) within the tissue of the Tecate cypress or buried as pupae in 
the leaf litter on the ground. Also, post-fire monitoring has been 
limited. We are only aware of post-fire monitoring being conducted in 
2004. Therefore, additional monitoring would be needed to determine the 
survival and recolonization rate of immature and adult butterflies 
following a fire.
    The petitioner did not provide information or data to substantiate 
the claim that excessive fires over the last several decades have 
reduced Thorne's hairstreak butterfly population numbers and disrupted 
metapopulation dynamics and stability. As stated in the ``Population 
Estimates/Status'' section of this finding, no quantitative data on 
population size exists nor do we have any information on the dispersal 
or movement behavior of this subspecies. Without this information, it 
is not possible to determine the subspecies's population structure 
(e.g., metapopulation or panmicitic) and subsequently, the impact of 
fire on population numbers and structure.
Habitat Fragmentation
    Information provided in the petition. The petitioner claimed 
fragmentation of Thorne's hairstreak butterfly populations, through 
fire, type conversion, and roads, poses a significant threat to the 
subspecies. The petitioner noted that habitat fragmentation reduces the 
area of Thorne's hairstreak butterfly habitat and isolates populations 
from one another. In addition, the petitioner claimed that 
fragmentation expands edge habitat, resulting in further stress on 
fragmented or small populations.
    Analysis of information provided in the petition and available to 
us at the time of petition review. Neither the petition nor information 
available support the claim that fragmentation threatens the subspecies 
existence within its known distribution on Otay Mountain. The best 
available information indicates Thorne's hairstreak butterfly is 
capable of re-colonizing immature Tecate cypress stands in recently 
burned areas. For example, as stated above, re-colonization of immature 
stands after a 1996 fire has been documented (Faulkner and Klein 2005). 
Also, as discussed above, surveys of potentially occupied habitat on 
Otay Mountain are incomplete, and, as discussed under Factor A, habitat 
patch distribution as defined by adult movement has not been 
determined.
Vulnerability of Small and Isolated Populations
    Information provided in the petition. The petitioner asserted that 
endemic taxa such as the Thorne's hairstreak butterfly are generally 
considered more prone to extinction than widespread species due to 
their restricted geographic range. According to the petition, the 
common factors that increase the vulnerability of small and isolated 
populations to extinction are demographic fluctuations, environmental 
stochasticity (i.e., random events), and reduced genetic diversity.
    Analysis of information provided in the petition and available to 
us at the time of petition review. Populations of Thorne's hairstreak 
butterfly are likely subject to population fluctuations. If occupied 
habitat is temporarily fragmented by fire, fluctuation in numbers could 
render small populations more vulnerable to stochastic extirpation. 
Small populations and isolation could subject the butterfly to genetic 
drift and restricted gene flow that may decrease genetic variability 
over time and could adversely affect the subspecies' viability. 
However, we lack the genetic or demographic evidence to support such 
claims in the petition, and potential isolation of small populations by 
fire appears to be short-term. Furthermore, surveys of potentially 
occupied habitat on Otay Mountain are incomplete and estimates of 
population status/size do not currently exist. Therefore, information 
in our files does not indicate small population size is a threat to 
this subspecies.
Global Climate Change
    Information provided in the petition. The petitioner asserted that 
butterflies are particularly sensitive to small changes in 
microclimates, such as fluctuations in moisture, temperature, or 
sunlight. According to the petition, studies of Edith's checkerspot 
(Euphydryas chalceona edithi) have verified speculation that whole 
ecosystems may move northward or shift in elevation as the Earth's 
climate warms (Parmesan and Galbraith 2004).
    Analysis of the information provided in the petition and available 
to us at the time of petition review. The petitioner did not provide 
specific information validating the claim that the Thorne's hairstreak 
butterfly may be endangered by global climate change. We recognize 
recent evaluations by Parmesan and Galbraith (2004) that whole 
ecosystems are seemingly being shifted northward. However, neither the 
petition nor our files provides anything more than speculation on the 
type, magnitude, or temporal effects of ecosystem changes that may be 
brought about by regional climate change. We are not aware of any 
documentation available or provided by the petitioner that directly 
links global warming as a threat to the subspecies, or how global 
warming specifically affects the subspecies. Therefore, we find that 
the petition does not contain substantial information suggesting that 
global climate change may be a factor that threatens the Thorne's 
hairstreak butterfly.

Finding

    We evaluated each of the five listing factors individually, and 
because the threats to Thorne's hairstreak butterfly are not mutually 
exclusive, we also evaluated the collective effect of these threats. 
The petition focused primarily on three listing factors: Factor A (the 
Present or Threatened Destruction, Modification, or Curtailment of the 
Species' Habitat or Range), Factor D (Inadequacy of Existing Regulatory 
Mechanisms), and Factor E (Other Natural or Manmade Factors Affecting 
the Continued Existence). More specifically, information in the 
petition suggests that fire poses the primary threat to Thorne's 
hairstreak butterfly habitat and populations because the subspecies' 
range occurs on lands susceptible to wildfires. However, it appears 
that frequency of fire in occupied habitat over the past century is not 
high enough on average to threaten the subspecies, and Tecate cypress 
populations on Otay Mountain are stable and potentially increasing 
overall. Within areas that have burned, the subspecies appears able to 
re-colonize over time.
    Also, we have determined that Federal regulations and activities 
(Wilderness Act, BLM fire suppression policy, Border Patrol enforcement 
activities, and MSCP) provide a significant level of protection for the 
Thorne's hairstreak butterfly and/or its habitat on Federal lands that 
include the subspecies entire known range. We will continue to work 
with the City and County of San Diego and the BLM to avoid and minimize 
impacts to the Thorne's hairstreak butterfly on their lands.

[[Page 44988]]

    We have reviewed the petition and literature cited in the petition 
and evaluated that information in relation to information available to 
us. After this review and evaluation, we find the petition does not 
present substantial scientific information to indicate listing the 
Thorne's hairstreak butterfly may be warranted at this time. Although 
we will not be commencing a status review in response to this petition, 
we will continue to monitor potential threats and ongoing management 
actions that might be important with regard to the conservation of the 
Thorne's hairstreak butterfly across its range. We encourage interested 
parties to continue to gather data that will assist with the 
conservation of the subspecies.

References Cited

    A complete list of all references cited herein is available, upon 
request, from our Carlsbad Fish and Wildlife Office (see ADDRESSES 
section above).

Author

    The primary authors of this notice are staff from the Carlsbad Fish 
and Wildlife Office (see ADDRESSES section above).

Authority

    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: August 1, 2006.
H. Dale Hall,
Director, Fish and Wildlife Service.
 [FR Doc. E6-12743 Filed 8-7-06; 8:45 am]
BILLING CODE 4310-55-P