2011 Federal Register, 76 FR 9991; Centralized Library; U.S. Fish and Wildlife Service - Federal Register, Volume 76 Issue 36 (Wednesday, February 23, 2011)

[Federal Register Volume 76, Number 36 (Wednesday, February 23, 2011)]
[Proposed Rules]
[Pages 9991-10003]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-4038]

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R8-ES-2010-0016; MO 92210-0-0008-B2]

Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List Thorne's Hairstreak Butterfly as Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 12-month petition finding.

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SUMMARY: We, the U.S. Fish and Wildlife Service, announce a 12-month
finding on a petition to list Thorne's hairstreak butterfly (Callophrys
[Mitoura] gryneus thornei) as endangered under the Endangered Species
Act of 1973, as amended (Act). After review of all available scientific
and commercial information, we find that listing Thorne's hairstreak
butterfly is not warranted at this time. However, we ask the public to
submit to us any new information that becomes available concerning the
threats to Thorne's hairstreak butterfly or its habitat at any time.

DATES: The finding announced in this document was made on February 23,
2011.

ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R8-ES-2010-0016. Supporting
documentation we used in preparing 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, Suite 101, Carlsbad, CA 92011. Please submit any
new information, materials, comments, or questions concerning this
finding to the above street address.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, Carlsbad
Fish and Wildlife Office, U.S. Fish and Wildlife Service, 6010 Hidden
Valley Road, Suite 101, Carlsbad, CA 92011; 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.

SUPPLEMENTARY INFORMATION:

Background

Section 4(b)(3)(B) of the Endangered Species Act of 1973, as
amended (Act)

[[Page 9992]]

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

Previous Federal Actions

On August 8, 2006, we published 90-day findings for both the
Thorne's hairstreak and the Hermes copper butterflies in the Federal
Register (71 FR 44980 and 71 FR 44966, respectively). The findings
concluded that the petitions and information in our files did not
present substantial scientific or commercial information indicating
that listing Thorne's hairstreak butterfly or Hermes copper butterfly
may be warranted. For a detailed history of Federal actions involving
Thorne's hairstreak butterfly prior to the 2006 90-day finding, please
see the August 8, 2006, Federal Register publication (71 FR 44980).
On March 17, 2009, Center for Biological Diversity (CBD) and David
Hogan filed a complaint for declaratory and injunctive relief
challenging the Service's decision not to list Thorne's hairstreak
butterfly and Hermes copper butterfly as endangered or threatened under
the Act. In a settlement agreement dated October 23, 2009 (Case No. 09-
0533 S.D. Cal.), the Service agreed to submit a new 90-day petition
finding for Thorne's hairstreak butterfly to the Federal Register by
April 2, 2010. As part of the settlement agreement, we agreed to
evaluate the October 25, 2004, petition filed by CBD and David Hogan,
supporting information submitted with the petition, and information
available in the Service's files, including information that has become
available since the publication of the negative 90-day finding in the
Federal Register on August 8, 2006. If the 90-day finding determined
that listing may be warranted, we agreed to submit a 12-month finding
for Thorne's hairstreak butterfly to the Federal Register by March 4,
2011. On April 5, 2010, we published a 90-day finding that determined
listing of Thorne's hairstreak butterfly as endangered may be warranted
(75 FR 17062). This notice constitutes the 12-month finding on the
petition to determine whether listing the Thorne's hairstreak butterfly
as endangered is warranted.

Subspecies Information

It is our intent to discuss only those topics directly relevant to
the listing of Thorne's hairstreak butterfly under the Act in this 12-
month finding. For more information on the taxonomy, biology, and
ecology of Thorne's hairstreak butterfly, please refer to the 90-day
finding published in the Federal Register on April 5, 2010 (75 FR
17062). That document is available on the Internet at http://www.fws.gov/Carlsbad and at http://www.regulations.gov (under docket
number FWS-R8-ES-2010-0016).

Taxonomy and Nomenclature

Thorne's hairstreak butterfly was first described as Mitoura
thornei based on a specimen collected in 1972 near Otay Lake by Fred
Thorne (Brown 1983, p. 246). Biologists questioned the classification
of Thorne's hairstreak butterfly as a species. Shields (1984, p. 53)
relegated it to a brown subspecies of the juniper hairstreak (species
or subspecies name loki) as Mitoura loki thornei. Scott (1986, p. 374)
also classified it as a subspecies, but under the name Callophrys
gryneus thornei, in part because he did not consider any taxa in
Mitoura as a genus distinct from Callophrys. The classification of
Mitoura thornei was evaluated in 1999 by the Committee on Scientific
Names of North American Butterflies (Committee). The Committee reached
consensus based on publications and arguments presented, and accepted
classification of Thorne's hairstreak butterfly as a subspecies of the
species Callophrys gryneus (Burns et al. 2000, p. 9). Subsequently, the
Committee prepared the second edition of the Checklist of English Names
of North American Butterflies in which Thorne's hairstreak butterfly
was classified as Callophrys gryneus thornei (Cassie et al. 2001, p.
9). Van Buskirk (2004) reviewed Thorne's hairstreak butterfly
classification for the Service; this review concurred with the
Committee's decision to classify Thorne's hairstreak butterfly as
Callophrys gryneus thornei.
The classification of Thorne's hairstreak butterfly continues to be
a focus of investigation. Recent work that includes mitochondrial DNA
and allozyme analysis indicates that Thorne's hairstreak is closely
related to juniper hairstreak (Shiraiwa 2010, p. 1; Pratt 2010, in
press), as originally suggested by Shields (1984, p. 53). Pratt's
(2010, in press, p. 9) work also appears to support classifying Mitoura
as a genus or subgenus, which would classify Thorne's hairstreak
butterfly as a subspecies of Mitoura loki (the juniper hairstreak).
Thorne's hairstreak butterfly has always been classified as a separate
entity at some level (species or subspecies), and therefore it is a
listable entity under the Act. As described above, recent work
indicates that it is best classified as a subspecies close to the
juniper hairstreak. The monophyletic group Mitoura may warrant
recognition as a separate genus in the future.
In this 12-month finding, we follow the most recent recommendation
from the North American Butterfly Association Names Committee (Cassie
et al. 2001, p. 9) and treat Thorne's hairstreak butterfly as a
subspecies named Callophrys gryneus thornei.

Habitat

Thorne's hairstreak butterfly habitat is characterized by interior
cypress woodland, also recently known as Callitropsis forbesii Woodland
Alliance (Tecate cypress stands) (Sawyer et al. 2009, pp. 101-102)
dominated by its host plant, Hesperocyparis forbesii (Tecate cypress).
This habitat is found on Otay Mountain, intermixed with chaparral
between approximately 800 feet (ft) (244 meters (m)) and 3,290 ft (1003
m) in elevation (i.e., the mountain peak). Adult Thorne's hairstreak
butterflies are known to feed on the nectar of Eriogonum fasciculatum
(California buckwheat), Ceanothus tomentosus (Ramona lilac), and Lotus
scoparius (deerweed) in the vicinity of stands of H. forbesii (Faulkner
and Klein 2005, p. 33). A recent study indicates Asclepias fascicularis
(narrowleaf milkweed) is also used as an adult nectar source throughout
the subspecies' range (Lucas 2009, pers. comm.). It is likely that
Thorne's hairstreak butterfly, like most butterflies, uses a variety of
plant species as nectar sources, and frequency of use is primarily
dependent on availability.
Thorne's hairstreak butterfly deposits eggs and feeds exclusively
on its larval host plant, Hesperocyparis forbesii, to complete its life
cycle (Brown 1983, p. 252). Williams and Congedo (2008)

[[Page 9993]]

studied aspects of larval host plant use by Thorne's hairstreak
butterfly. They recorded number of eggs per H. forbesii tree, placement
of eggs within trees, location of feeding damage on trees, and larval
food choice, comparing mature (cone-bearing) trees to immature trees
(no cones) (Williams and Congedo 2008, pp. 6-13). No significant
difference was found between use of young or recent shoots (appressed
scale leaves and stems) from mature and immature trees (Williams and
Congedo 2008, pp. 15-18). Williams and Congedo (2008, p. 14) also noted
that Thorne's hairstreak butterflies occupied stands of trees not more
than 5 years old, and that approximately 7 percent of new fire regrowth
trees were producing cones. Williams and Congedo (2008, p. 19)
concluded larvae could develop by feeding on tissue from immature or
mature trees; thus the availability of host plants for egg deposition
in an occupied area is not likely limiting. These results confirm the
hypothesis drawn from adult presence in new post-fire growth that
oviposition is not limited by host plant age, as discussed in the 2006
and 2010 90-day findings (71 FR 44980 and 75 FR 17062, respectively).
Therefore, the best available information indicates Thorne's hairstreak
butterfly larvae can utilize any available life stage of H. forbesii to
complete its life cycle.
Nectar source abundance is also a key factor in determining
Thorne's hairstreak butterfly habitat suitability. Van Reusel et al.
(2006, pp. 201, 207) studied a related species of hairstreak butterfly
and, using predictive models, found that host plant and nectar source
were the primary factors predicting green hairstreak butterfly
distribution. Nectar sources are critical to support courtship, mating,
and oviposition behaviors of butterflies such as Thorne's hairstreak
butterfly (Williams and Congedo 2008, p. 20).

Biology

The 90-day finding (75 FR 17062; April 5, 2010) incorrectly
characterized the flight seasons as described in Faulkner and Klein
(1995). Thorne's hairstreak butterfly has two flight periods per year
(bivoltine). The first adult emergence and abundance peak occurs in
late February through March and possibly early April, depending on
winter rainfall. A second adult abundance peak occurs in late May or
early June, with a possible third in September if there are summer
monsoon rains (Klein 2010a, p. 1).

Distribution and Population Status

We evaluated available information on the current range, historical
range, and population status of Thorne's hairstreak butterfly to
develop the most current understanding of its distribution and status.
Our knowledge of Thorne's hairstreak butterfly's range has greatly
increased over the past 10 years. The known pre-2003 fire distribution
of Thorne's hairstreak butterfly approximately encompassed the
northeast quadrant of Otay Mountain, including locations just southwest
of the peak and a lower-elevation location east of Otay Lakes (Klein
2010a, p. 2). The 2003 Mine Fire (also called the Otay Fire) perimeter
encompassed all habitats where butterflies had been observed; however,
post-fire surveys revealed a cluster of locations occupied by Thorne's
hairstreak butterflies in the southwest quadrant of Otay Mountain
outside of the mapped fire perimeter (Klein 2010a, p. 11). The 2007
Harris Fire perimeter encompassed the lower north and east slopes of
Otay Mountain, affecting a large portion of cypress forest in the
northwest quadrant near Otay Lakes. Post-2007 fire surveys on Otay
Mountain conducted by Lucas in 2010 included all areas within the
species' range on Otay Mountain except known historical locations at
the easternmost edge of the species' range (Lucas 2010), thus we are
uncertain about the current status of the species at this easternmost
edge of the species range. Only one stand of trees (that was not a
known historical location for Thorne's hairstreak butterflies) was
surveyed in the eastern area; no butterflies were observed (Lucas 2010;
Klein 2010a, pp. 2, 12). Lucas also recorded a new Thorne's hairstreak
butterfly occurrence location in an area within the northwest quadrant
of Otay Mountain in 2010, thus expanding the pre-2007 fire known range
(Lucas 2010). The newly discovered northwestern Otay Mountain
observation location is over 1.5 miles (mi) (2 kilometers (km)) from
the nearest previous Thorne's hairstreak butterfly observation in the
northeast quadrant (Lucas 2010; Klein 2010a, pp. 2, 12).
Surveys by Lucas on Otay Mountain in 2010 revealed the presence of
Thorne's hairstreak butterfly throughout the majority of Hesperocyparis
forbesii that burned in the 2003 fire, the 2007 fire, and in areas
burned by both fires (unpublished data 2010).
Additionally, the known distribution of Thorne's hairstreak
butterfly on Otay Mountain is greater than was known at the time of the
2004 petition. Therefore, the persistence of the butterfly in
previously burned areas and the increase in the known butterfly
distribution indicate that Thorne's hairstreak butterfly has either
successfully recolonized burned areas or persisted within mapped fire
perimeters on Otay Mountain.
A previously unknown Thorne's hairstreak butterfly observation was
also documented in 2010 off of Otay Mountain at a lower elevation in
approximately 1 ac (0.4 ha) of atypical, created habitat, which
suggests that Thorne's hairstreak butterfly either has the ability to
recolonize small Hesperocyparis forbesii stands at lower elevations or
that this observation may represent a new occurrence that was not
previously documented. Of note, this new location:
(1) Is in the Otay River Valley, at the mouth of O'Neal Canyon
(Busby 2010a, pp. 1-2; Cooper 2010a, p. 1) and is outside the known
Thorne's hairstreak butterfly range;
(2) Is over 2.5 mi (4 km) from, and over 1000 ft (305 m) lower in
elevation than, the nearest occupied site upslope at the base of Otay
Mountain (as described by Lucas 2010, slide 15; Google Earth imagery);
(3) Is approximately 500 ft (152 m) lower in elevation than the
lowest previously recorded observation east of Otay Lake (site 5
described by Klein 2010a, p. 2); and
(4) Occurs on land conserved and managed by the City of Chula
Vista, which is the only known occupied area located entirely outside
of the Bureau of Land Management (BLM) Otay Mountain Wilderness (Klein
2010b, p. 1).
The June 15 (Busby 2010a, pp. 1-2; Cooper 2010a, p. 1) and June 23,
2010, (Anderson 2010, p. 1; Cooper 2010b, pp. 1-2) observations of
adult butterflies at the Otay River Valley location are also the latest
ever recorded for Thorne's hairstreak butterfly during a flight season
(Klein 2010b, p. 1). This late record is likely the result of unusually
cool spring weather in 2010, creating prolonged and cooler moist river
valley microclimate conditions. A June 1996 satellite image does not
show Hesperocyparis forbesii stands at this location (Google Earth
historical imagery accessed 2010). Although we do not have
documentation of how or why the H. forbesii was established at this
location, analysis of historical satellite imagery from 1996 to 2010
and observations of individuals familiar with the site lead us to
believe the trees were planted as seedlings from a nursery to replace
native vegetation removed when a gas utility pipeline was installed in
1996 (Anderson 2010, p. 1;

[[Page 9994]]

Cooper 2010b, pp. 1-2; Busby 2010b, p. 1). Regardless, occupancy of
this newly discovered site in created habitat supports the hypothesis
that Thorne's hairstreak butterfly is opportunistic and relatively
resilient (i.e., able to persist at a new, lower elevation level in
more moist microhabitat conditions than previously known to occur).
Results from a previous hairstreak butterfly movement study also
support the hypothesis of natural colonization. Specifically, Robbins
and Small (1981, p. 308) studied movement of hairstreak butterflies
(Lycaenidae: Eumaeini) in Panama and reported:
(1) Observations of 128 species (47 percent of the known Panamanian
hairstreak butterfly fauna) blown across the landscape by winds with
speeds of 10 to 25 miles per hour (mi/hr) (15 to 40 kilometers per hour
(km/hr));
(2) More than 80 percent of these species were blown through
habitats where they are not normally found;
(3) Some species normally found in high-elevation habitats were
observed 3 mi (5 km) from the nearest upland habitat; and
(4) Seventy percent of the observed specimens were females (whereas
typical sex ratios for hairstreak butterfly populations have more males
than females), and 74 percent of captured females (a subset of those
observed) had been mated.
Robbins and Small (1981, pp. 311-12) concluded hairstreak
butterflies are likely to be dispersed by wind and can successfully
colonize suitable downwind habitats. In southern California, annual
Santa Ana winds often produce westerly winds of 25 to 37 mi/hr (40 to
60 km/hr) from fall through spring (Westerling et al. 2004, p. 290),
and likely disperse insects. We believe this type of wind-assisted
dispersal occurs at Otay Mountain, and is a likely explanation of how
Thorne's hairstreak butterfly became established in the Otay River
Valley stand of Hesperocyparis forbesii.
The 90-day finding (75 FR 17062; April 5, 2010) stated the current
distribution of Hesperocyparis forbesii in the Otay Mountain area
encompasses 454 ac (183 ha) post-2003 fire (Lucas 2009, unpublished
data), and compared this to historical Otay Mountain records that
indicate H. forbesii once covered approximately 7,500 ac (3,035 ha)
(California Natural Diversity Database (CNDDB) GIS database 2003).
After further evaluation of all available host plant distribution
information, we determined the acreage values cannot be compared as
described in the 90-day finding because the values are a result of
different mapping methodologies. Data from 2007 revealed that H.
forbesii on Otay Mountain encompasses approximately 7,556 ac (3,058 ha)
(CNDDB GIS database 2007). Additionally, the San Diego Association of
Governments (SANDAG) produced a vegetation map of Southern Interior
Cypress Forest on Otay Mountain equal to 5,693 ac (2,304 ha) (SANDAG
GIS database, 1995). The smallest and most recent H. forbesii
distribution area estimate of 454 ac (183 ha) cited in the 90-day
finding (75 FR 17062; April 5, 2010) reflects stand-scale mapping
focused on groups of 20 or more trees greater than 3.3 ft (1 m) in
height, with smaller stands included when encountered incidentally
(Forister and Lucas 2009, p. 1).
Comparison of the CNDDB and SANDAG vegetation databases also
indicates differences in mapping methodology. The two vegetation-based
mapping methods vary in the areas mapped as occupied by Hesperocyparis
forbesii, with only approximately half the area mapped in 1995 (SANDAG
GIS database, before the 2003 fire) overlapping occupied areas mapped
in 2007 (CNDDB GIS database, after the 2003 fire). Field inspection of
three H. forbesii stands along the Minewawa truck trail that were
within the 2003 fire perimeter revealed new growth of immature cypress
throughout (Anderson 2010, p. 1). One H. forbesii location did not
correspond with any location mapped by Lucas (2010 unpublished data),
while the other two corresponded with Lucas's mapped areas and observed
Thorne's hairstreak butterfly observations (Lucas 2010, unpublished
data). Furthermore, approximately one-third of mapped Thorne's
hairstreak butterfly observation locations fall outside all three
mapped H. forbesii distributions discussed above.
Our current analysis of Thorne's hairstreak butterfly habitat
distribution indicates most of the habitat is relatively protected.
Approximately 88 percent of cypress woodland is within the BLM Otay
Mountain Wilderness area, and 11 percent is within the planning area of
the San Diego Subarea Plan under the San Diego MSCP (see Factor A
discussion below). The remaining one percent is privately owned.
Occupied habitat within the City of Chula Vista Subarea Plan planning
area is approximately 1 ac (0.4 ha; see above discussion).
To summarize, available vegetation mapping of cypress forest can
approximate the Thorne's hairstreak butterfly population distribution,
while Lucas' data map of cypress forest (which is on a stand (sub-
population)-scale) is not yet comprehensive and thus cannot approximate
the Thorne's hairstreak butterfly population distribution. It is not
clear if either scale of cypress mapping corresponds with Thorne's
hairstreak butterfly habitat distribution at either a butterfly
population distribution or sub-population level. As a result, we are
unable to accurately estimate the change in distribution of Thorne's
hairstreak butterfly habitat on Otay Mountain because of the differing
mapping techniques and because Hesperocyparis forbesii stands are still
recovering from the 2003 and 2007 fires.
Finally, Geographic Information System (GIS) analysis of historical
fire perimeters indicates the majority of Thorne's hairstreak butterfly
habitat has burned only once or twice in the past 100 years (see Factor
A discussion below). All available data indicate that because cypress
forest regrows after fire, and Thorne's hairstreak butterflies
recolonize cypress forest regardless of host plant age, the
distribution of habitat has not changed significantly following the
recent fires.
While individual Thorne's hairstreak butterflies are likely lost
when fire burns stands of Hesperocyparis forbesii (as discussed in the
90-day finding (75 FR 17062; April 5, 2010)), more recent data
(discussed above) support the hypothesis that Thorne's hairstreak
butterfly populations are relatively resilient to fire. Discovery of
occupied habitat in 2007 and 2010 within the 2003 and 2007 fire
perimeters, and the newly colonized created habitat in 2010 in the Otay
River Valley (see above discussion) indicates Thorne's hairstreak
butterflies can move relatively considerable distances, readily
colonize new stands of H. forbesii, and increase their numbers to
detectable levels over a period of 5 to 10 years. The recently recorded
Otay River Valley location represents a confirmed Thorne's hairstreak
butterfly range expansion over the past 10 years. Furthermore, we have
no evidence supporting a permanent range contraction or curtailment
anywhere throughout the subspecies' known distribution.

Summary of Information Pertaining to the Five Factors

Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR part 424) set forth procedures for adding species to, removing
species from, or reclassifying species on the Federal Lists of
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of
the Act, a species may be determined to be endangered or threatened
based on any of the following five factors:

[[Page 9995]]

(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
In making this 12-month finding, information pertaining to Thorne's
hairstreak butterfly in relation to the five factors provided in
section 4(a)(1) of the Act is discussed below. In making our 12-month
finding on the petition, we considered and evaluated the best available
scientific and commercial information.
In considering whether a species warrants listing under any of the
five factors, we look beyond the species' exposure to a potential
threat or aggregation of threats under any of the factors, and evaluate
whether the species responds to those potential threats in a way that
causes actual impact to the species. The identification of threats that
might impact a species negatively is not sufficient to compel a finding
that the species warrants listing. The information must include
evidence indicating that the threats are operative and, either singly
or in aggregation, affect the status of the species. Threats are
significant if they drive, or contribute to, the risk of extinction of
the species, such that the species warrants listing as endangered or
threatened, as those terms are defined in the Act.

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

The following potential threats that may affect the habitat or
range of Thorne's hairstreak butterfly, discussed in this section,
include: (1) Wildfire, (2) climate change as it relates to wildfire
(climate change is discussed further under Factor E below), (3) habitat
fragmentation, and (4) road and firebreak construction required for
national security and fire management (U.S. Customs and Border
Protection) activities. We also discuss benefits to Thorne's hairstreak
butterfly and its habitat in the Habitat Conservation Plans (HCPs) and
Natural Community Conservation Plans (NCCPs) section below. In the 90-
day finding (75 FR 17062; April 5, 2010), we indicated that based on
the petition, recreational traffic, prescribed burns, and grazing were
potential threats to Thorne's hairstreak butterfly. In the development
of this 12-month finding, we further investigated the possibility that
these activities were potential threats and found no evidence that
recreational traffic, prescribed burns, or grazing were occurring or
affecting the species or its habitat. Therefore, we have determined
that these factors are not threats to the subspecies (see discussions
below under the Road and Firebreak Construction section, the Factor D
discussion, and the Factor E discussion).
Wildfire and Climate Change Related to Wildfire
Fire regimes are based on the temporal and spatial patterns of
ignition sources, fuel, weather, and topography (Pyne et al. 1996, p.
48). It is also important to understand that fire severity, or the
ecological impact of a fire and recovery of an ecosystem (Keeley and
Fotheringham 2003, p. 231), can be different from fire intensity, or
the energy released per length of fire front (Borchart and Odion 1995,
p. 92). Additionally, large fires are not always equivalent to high-
intensity fires (Keeley and Fotheringham 2003, p. 231). This is
particularly important when assessing effects of fire on chaparral
communities. Fire often burns in a mosaic pattern at different
intensities, thereby resulting in differing levels of effects on
particular species and habitats. Therefore, the inclusion of a specific
mapped fire perimeter is not a reliable indicator of the level of
mortality or habitat destruction.
According to Keeley and Fotheringham (2003, pp. 242-243), the
historical natural fire regimes in southern California were likely
characterized by many small lightning-ignited fires in the summer, a
few large fires in the fall, and a variable fire intensity. However,
the fire frequency (number of fires in a given area, not necessarily
overlapping) has increased in North American Mediterranean Shrublands
in California since about the 1950s. Southern California has
demonstrated the greatest increase in wildfire ignitions, primarily due
to an increase in population density beginning in the 1960s, and thus
accessibility to new areas (Keeley and Fotheringham 2003, p. 240).
We analyzed the past 40 years of fire patterns at Otay Mountain and
found that the spatial and temporal historical fire regime described by
Keeley and Fotheringham (2003) is confirmed at this location as
illustrated in Table 1.

Table 1--Spatial and Temporal Historical Fire Regime and Fire Impact on Southern Interior Cypress Forest for
Otay Mountain, San Diego County, California
----------------------------------------------------------------------------------------------------------------
Cypress Cypress
Total fire forest within forest within
Year perimeter Number of fire fire
(acres) fires perimeter perimeter
(acres) (hectares)
----------------------------------------------------------------------------------------------------------------
1971............................................... 56.04 1 18.97 7.67
1976............................................... 1,656.05 1 28.68 11.6
1978............................................... 600.48 1 22.67 9.17
1979............................................... 7,557.45 3 1,062.83 430.11
1980............................................... 3,313.64 1 36.97 14.96
1981............................................... 371.67 1 60.5 24.48
1982............................................... 1,076.56 4 124.42 50.35
1983............................................... 666.87 2 106.91 43.26
1985............................................... 188.37 1 19.14 7.74
1986............................................... 965.5 1 0.34 0.13
1987............................................... 54.71 1 3.54 1.43
1989............................................... 129.8 1 0.06 0.02
1990............................................... 63.33 1 7.4 2.99
1993............................................... 641.76 1 24.24 9.81
1994............................................... 2,983.35 1 103.09 41.71
1995............................................... 156.37 2 14.73 5.96
1996............................................... 18,460.02 5 4,186.08 1,694.05

[[Page 9996]]

1999............................................... 118.48 1 11.14 4.51
2003............................................... 44,884.10 1 7,548.9 3,054.95
2005............................................... 359.15 2 37.94 15.35
2007............................................... 90,738.46 1 1,279.76 517.9
2008............................................... 124.75 2 0.67 0.27
----------------------------------------------------------------------------------------------------------------

The concern for wildfire effects to Thorne's hairstreak butterfly
is primarily associated with loss of Hesperocyparis forbesii trees
prior to the production of seed cones, which can result in the
extirpation of a given stand (see Habitat section above).
Hesperocyparis forbesii is a small tree generally associated with
``chaparral ecosystems in southern California and northern Baja
California, Mexico'' (de Gouvenain and Ansary 2006, p. 447). Chaparral
is considered a crown-fire ecosystem, meaning ecosystems which ``have
endogenous mechanisms for recovery that include resprouting from basal
burrs and long-lived seed banks that are stimulated to germinate by
fire'' (Keane et al. 2008, p. 702). These ecosystems are also resilient
to high-intensity burns (Keeley et al. 2008, p. 1545). Seed cones of
western cypress (Hesperocyparis) mature in the second year, generally
remain closed at maturity, and open after many years or in response to
fire (Adams et al. 2009, p. 180). As a result, H. forbesii, like most
western cypresses, has serotinous or closed-cones that allow the
species to withstand fire.
While Zedler (1977, p. 456) indicated that cone production for
Hesperocyparis forbesii begins around 10 years of age, Dunn (1986, p.
369) reported production ``begins at about 5-7 years of age, but is
sporadic until the trees reach about 30 years in age.'' Dispersal and
germination of seeds is predominantly a result of fire, which results
in death of the parent plant (Zedler 1977, p. 456). However, Zedler
(2010a, pp. 1-2) stated that ``H. forbesii does not require fire to
germinate and establish seedlings, although the frequency with which
germination without fire occurs in natural stands is low, and the
survival of seedlings that do germinate is probably even lower.''
Moreover, given that H. forbesii is a long-lived (more than 100 years)
tree (Markovchick-Nicholls 2007, p. 4), with some individual trees on
Guatay Mountain estimated to exceed 150 years in age (Dunn 1986, p.
369), the need for reproduction in the absence of fire is low.
Hesperocyparis forbesii biology, status, and management needs were
recently discussed at a workshop on June 16, 2010 (Burrascano 2010, pp.
1-4). Some attendees indicated that the H. forbesii stands on Otay
Mountain are declining over the long term and that increased fire
frequency poses a threat to the tree (Burrascano 2010, pp. 1-4);
however, this assumes a significant correlation between the increased
fire frequency in southern California and a decrease in the burn return
interval within any given occupied cypress stand. Regarding the
likelihood of extirpation, Zedler (2010b, p. 2) stated that ``it is
very unlikely this species will be [extirpated] in 100 years, almost
zero chance in 50.'' Specifically, Zedler (2010b, p. 1) believes the
statistical probability of H. forbesii being extirpated from Otay
Mountain (assuming relative independence of stands) is very low or
insignificant. Zedler (2010b, p. 1) also concluded that as the number
of fires in any area of ground per time increases, the average area
burned in any given fire decreases; hence, to extirpate H. forbesii
completely would require almost a saturation of ignitions, which is
also unlikely. This information supports the unlikely extirpation of H.
forbesii in the foreseeable future.
Regarding the likelihood of decline, Markovchick-Nicholls (2007, p.
v) used available data and stochastic matrix population models to
assess the current risk of decline of Hesperocyparis forbesii under a
range of southern California fire regime scenarios, and to rank
management options and research priorities. Her model results suggest
that H. forbesii will decline under most fire regime scenarios over the
long term, but that this trend may be difficult to detect in the short
term (Markovchick-Nicholls 2007, p. 41). Model results indicated that
fire breaks could be highly effective for H. forbesii conservation, if
designed to minimize removal of H. forbesii (Markovchick-Nicholls 2007,
p. 41). In contrast, collection of seed in older H. forbesii stands for
distribution in reproductively immature stands poses much less risk to
the species, but also has much less dramatic effects on the persistence
of the species than fire breaks do, even if successful (Markovchick-
Nicholls 2007, p. 41). Current BLM policy (BLM 2010a, pp. 6-7) dictates
any future firebreak and road construction projects in Thorne's
hairstreak butterfly habitat on Otay Mountain minimize impacts to the
butterfly (see also Factor D discussion below), while reducing the
threat of fire to the subspecies and its host plant by slowing the
spread of fire once ignited.
To address the issue of fire and how it relates to Thorne's
hairstreak butterfly habitat loss, we conducted several GIS-based
analyses of past fire frequencies and burn patterns on Otay Mountain.
As described in the 90-day finding (71 FR 44980; August 8, 2006), we
used GIS data in our files to overlay Hesperocyparis forbesii
distribution on the map provided in the petition illustrating multiple
fires that have burned through and near Thorne's hairstreak butterfly
locations over the past century, and determined the majority of H.
forbesii was within one or two fire perimeters during the 93-year
period from 1910 to 2003. Furthermore, as discussed above, the areas of
overlap between the 2003 and 2007 fire perimeters were relegated to
lower elevation areas where host plant density is lowest. This result
corresponds with the most conservative fire regime scenario in the
Markovchick-Nicholls models discussed above (46 years), which is the
scenario where the population appeared the most stable (Markovchick-
Nicholls 2007, p. 41). The above information further supports the
unlikely decline or extirpation of H. forbesii in the foreseeable
future.
Using the most recent estimate (based on 2010 data) of 7,549 ac
(3,055 ha) (CNDDB GIS Database 2010) of cypress forest on Otay
Mountain, we calculated the overlap for the three largest fires in the
last 15 years (1996, 2003, and 2007).

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In 1996, 55 percent of cypress forest was within a mapped fire
perimeter. In 2003, 100 percent of the cypress forest was within the
mapped fire perimeter. In 2007, 17 percent of cypress forest was within
the mapped fire perimeter. One hundred percent of the cypress forest
within the 1996 fire perimeter was also within the 2003 fire perimeter,
whereas only 17 percent of the area within the 2003 perimeter was also
within the 2007 fire perimeter. Over the last 15 years, only 9 percent
of cypress forest was within all three fire perimeters, and one
approximately 97-ac (39-ha) stand near the peak within the mapped 2003
fire perimeter is estimated to have not burned in approximately 40
years (Allison 2011, p. 1). The 2007 Harris Fire perimeter encompassed
the lower north and east slopes of Otay Mountain, overlapping with the
2003 burn perimeter primarily around the base of the mountain,
indicating the pattern observed by Dunn (1984, p. 90) has not changed
significantly over the past 27 years (1983-2010). In 1986, Dunn (p.
374) concluded most of the cypress on Otay Mountain were reaching full
maturity and a fire would result in little damage to the population,
because it would in fact result in maximum seed dispersal and
recruitment.
Despite multiple fires over the last four decades on and around
Otay Mountain (see Table 1), our analysis confirms Dunn's conclusion
that fire does not have a significant impact on the cypress forest on
Otay Mountain (Dunn 1986, p. 374). A recent survey documented that not
all Hesperocyparis forbesii individuals within mapped fire perimeters
are burned (Anderson 2010, p. 1). Only 11 of 122 Thorne's hairstreak
butterfly observation locations recorded in 2010 by Lucas (unpublished
data 2010) and only 17 percent of the associated cypress forest fell
within both the 2003 and 2007 mapped fire perimeters (Carlsbad Fish and
Wildlife Office GIS database). Throughout the areas that burned again
in 2007, cypress regrowth and Thorne's hairstreak butterflies were
observed in 2010. Furthermore, recent border fence construction and
other enforcement activities in the Otay Mountain Wilderness area have
reduced foot traffic by illegal immigrants from Mexico (Ford 2010, p.
1), reducing the likelihood of fire ignition resulting from this
source.
As described above, Santa Ana winds and human-caused ignitions are
important factors in southern California's shrubland and forest fire
regimes. Because the Santa Ana wind events in fall and winter are
driven by large-scale patterns of atmospheric circulation, researchers
have developed projections for Santa Ana Occurrence (SAO) using global
climate models (GCM) (Miller and Schlegel, 2006, p. 1). Results
obtained from one GCM do not show an increase in the total number of
annual SAOs; however, they did find a temporal shift in SAOs, with a
decrease during the months of September and October and an increase in
December (Miller and Schlegel, 2006, p. 3). The effects of this shift,
coupled with predicted decreased precipitation (see Climate Change
section in Factor E discussion below) to fire regime are unclear;
however, December and January are typically the wettest months on
record in Southern California (National Oceanic and Atmospheric
Administration 2005). This temporal shift of SAOs from a time following
the driest period of the year (May to October) to after the fall and
winter rains begin (Scripps Institute of Oceanography 2010) would
likely reduce the potential for and impact of wind and human-caused
ignitions in southern California.
The output from climate change models predicts a 50-percent
contraction in mixed evergreen woodland and shrubland vegetation
(general vegetation types that may include Hesperocyparis forbesii
stands) in California for the time period from 2070 to 2099 (Lenihan et
al. 2003, p. 1674) (for recent information on future climate
predictions, see Factor E discussion). Lenihan et al. (2003, p. 1674)
found that the most prominent feature of the vegetation class's
response to the drier model scenario was the advancement of grassland
into the historical range of mixed evergreen woodland and shrubland.
Such vegetation changes could reduce host plant and nectar source
availability for Thorne's hairstreak butterfly, as woody vegetation
declines and grasses replace native flowering forbs. Based on the above
discussion, nectar source availability may be a determining factor in
Thorne's hairstreak butterfly occupancy; however, the general climate
change vegetation effect models (Lenihan et al. 2003, p. 1674) found
the simulated response to changes in precipitation were complex,
involving changes in tree-grass competition mediated by fire.
We are unable to predict the changes in climate, especially on a
localized, small scale such as Otay Mountain, as well as what the
impacts to Thorne's hairstreak butterfly and its habitat may be because
this area is small relative to the resolution of vegetation change
prediction models (which used climate models of intermediate scale to
predict vegetation responses) and contains a relatively unique
community dominated by the rare endemic cypress (see also Factor E
discussion). While uncertainty exists regarding the potential effects
of climate change on wildfire and habitat loss, and despite the
increasing frequency of fires in southern California, the best
available information does not indicate the average burn return
interval per given area of cypress forest is decreasing, and it does
indicate ignition sources on Otay Mountain have been reduced compared
to historical levels; therefore, wildfire has not been, and is not
likely to be, a significant threat to the Thorne's hairstreak butterfly
or its habitat now or in the foreseeable future.
Habitat Fragmentation
We examined the possibility of habitat fragmentation affecting
Thorne's hairstreak butterfly. The connectivity of habitat occupied by
a butterfly population is not defined by host plant distribution at the
scale of host plant stands or patches, but rather by adult butterfly
movement that results in interbreeding (see Service 2003a, pp. 22, 162-
165). Any loss of resource contiguity on the ground that does not
affect butterfly movement, such as burned vegetation or road
construction through stands of cypress, may degrade habitat but does
not fragment a population. Therefore, in order for butterfly habitat to
be considered fragmented, movement must be prevented by a barrier, or
the distance between remaining host plants where larvae develop must be
greater than adult butterflies will move to mate or deposit eggs. If it
occurred, habitat fragmentation might create smaller, more vulnerable
populations (see Factor E discussion below); however, the best
available information indicates that habitat fragmentation has not
occurred on Otay Mountain (see Distribution and Population Status
section above). Hesperocyparis forbesii has demonstrated an ability to
recolonize after fire events on Otay Mountain, and data obtained since
publication of the 2010 90-day finding (75 FR 17062) indicate Thorne's
hairstreak butterfly is able disperse through wind events between any
temporarily isolated patches of H. forbesii (see Distribution and
Population Status section above). Therefore, we have determined that
habitat fragmentation is not a threat to the subspecies now, nor is it
likely to become so in the foreseeable future.
Road and Firebreak Construction
Thorne's hairstreak butterfly habitat is relatively protected from
most sources of habitat destruction, modification, or

[[Page 9998]]

curtailment because approximately 99 percent of its potential habitat
(mapped Interior Cypress Forest vegetation; CNDDB GIS database 2007) is
within publicly owned areas that are conserved and managed, primarily
within the BLM Otay Mountain Wilderness and San Diego Multiple Species
Conservation Program (MSCP) subarea plan preserves (see Habitat
Conservation Plans (HCPs) and Natural Community Conservation Plans
(NCCPs) section and Factor D discussion below).
Although road and firebreak construction has occurred in the past
in stands of Hesperocyparis forbesii where Thorne's hairstreak
butterflies have been observed, these impacts have been relatively
limited based on our qualitative comparison of Thorne's hairstreak
butterfly and host plant locations with Google Earth satellite imagery
of roads and firebreaks. Because U.S. Customs and Border Protection
recently completed construction of the border fence and expanded the
associated ``pack trail'' into a wider ``truck trail'' to accommodate
vehicles, the need for further significant Border Patrol-related
construction activities is not anticipated (Ford 2010, p. 1). Any
future firebreak and road construction projects that do occur in
Thorne's hairstreak butterfly habitat on Otay Mountain will be planned
so as to minimize impacts to the butterfly (see also Factor D below),
while reducing the threat of fire to the subspecies and its host plant
by slowing the spread of fire once ignited (BLM 2010a, pp. 6-7).
Finally, Williams and Congedo (2008, p. 19) concluded that existing
traffic corridors on Otay Mountain did not appear to be detrimental to
Thorne's hairstreak butterfly unless increasing human traffic
contributes to increasing fire danger.
The status of the Otay Mountain area as predominantly wilderness
area and preserve (which are managed) indicates this area is unlikely
to receive increased legal human traffic. Furthermore, as noted above,
recent border fence construction and other enforcement activities in
the Otay Mountain Wilderness area have reduced illegal human traffic
(Ford 2010, p. 1), thereby reducing the likelihood of fire ignition by
this source. Therefore, road and firebreak construction is not a
significant threat to the subspecies now, nor is it likely to become so
in the foreseeable future.
Habitat Conservation Plans (HCPs) and Natural Community Conservation
Plans (NCCPs)
Habitat conservation plans (HCPs) and natural community
conservation plans (NCCPs) benefit Thorne's hairstreak butterfly
through conservation, management, and monitoring. Habitat conservation
plans are developed under section 10 of the Act to support issuance of
permits that authorize the limited incidental take of listed species in
return for conservation and management of the species and their
habitats. The NCCP program is a cooperative effort involving the State
of California and numerous private and public partners to protect
regional habitats and species. The primary objective of NCCPs is to
conserve natural communities at the ecosystem scale while accommodating
compatible land uses. NCCPs help identify, and provide for, the
regional or area-wide protection of plants, animals, and their habitats
while allowing compatible and appropriate economic activity. Many NCCPs
are developed in conjunction with HCPs prepared under the Act.
The San Diego Multiple Species Conservation Program (MSCP) is a
subregional HCP and NCCP made up of several subarea plans that has been
in place for more than a decade. Under the umbrella of the MSCP, each
of the 12 participating jurisdictions is required to prepare a subarea
plan that implements the goals of the MSCP within that particular
jurisdiction.
Both Thorne's hairstreak butterfly and Hesperocyparis forbesii are
covered species under the County of San Diego MSCP Subarea Plan,
although neither the butterfly nor H. forbesii are covered species
under the City of Chula Vista MSCP Subarea Plan. The County of San
Diego MSCP Subarea Plan encompasses the majority (859 ac (348 ha)) of
H. forbesii habitat (Interior Cypress Forest; CNDDB GIS database 2007)
outside of the Otay Mountain Wilderness. The remainder of the H.
forbesii habitat outside of the Otay Mountain Wilderness (approximately
60 ac (24 ha)) is privately owned in an Amendment Area for the San
Diego MSCP Planning Area (see discussion below). Within the County of
San Diego MSCP Subarea Plan, over 99 percent of H. forbesii habitat
(Tecate Cypress Forest) is planned for conservation and management
(County of San Diego 2008a, Part 3, Section 2, p. 7), and the majority
has already been acquired for conservation.
As noted above, Thorne's hairstreak butterfly and Hesperocyparis
forbesii are covered species under the subarea plan (Service 1998, p.
6), which requires protection of Thorne's hairstreak butterfly host
plants and local chaparral species used as nectar sources. The
Framework Management Plan for the County of San Diego Subarea Plan
under the MSCP (County of San Diego 2008b, p. 2; Framework Management
Plan) requires the use of specific adaptive management techniques
directed at the conservation and recovery of covered species, such as
actions that assure wildfires do not occur too frequently in areas
where species are sensitive to fire. The Framework Management Plan also
provides for biological monitoring and preparation of an annual report,
and based upon this review and biological monitoring effort,
adjustments in the management goals can be made as necessary (County of
San Diego 2008b, p. 2). Because Thorne's hairstreak butterfly is
required to be conserved and adaptively managed and monitored under the
County of San Diego Subarea Plan, we anticipate land management to
protect Thorne's hairstreak butterfly and its habitat will continue to
be implemented under the County of San Diego Subarea Plan.
Additionally, the Memorandum of Understanding (MOU) on cooperation
in habitat conservation planning and management issued by BLM in 1994,
in conjunction with the development of the County of San Diego Subarea
Plan under the MSCP (BLM 1994, pp. 1-8), also applies to the Otay
Mountain Wilderness because it falls entirely within the boundary of
this subarea plan. As outlined in the MOU (BLM 1994, p. 3), BLM is
committed to managing their lands (i.e., Otay Mountain Wilderness) to
``conform with'' the County of San Diego Subarea Plan, which in turn
requires protection of Thorne's hairstreak butterfly's larval host
plant, Hesperocyparis forbesii, and local chaparral species used as
nectar sources. Therefore, protections provided by the County of San
Diego Subarea Plan under the MSCP to Thorne's hairstreak butterfly and
its habitat also apply to the Otay Mountain Wilderness.
The 90-day finding (75 FR 17062; April 5, 2010) states,
``Approximately 48 ac (19 ha) of Hesperocyparis forbesii habitat fall
under the [County of San Diego Subarea Plan], which strives for fire
management and prevention to restore the previous 25-year [burn return
interval]''; however, we have since determined this statement is not
accurate. The statement was based on the 1994 BLM South Coast Resource
Management Plan that specifies a minimum planned 25-year burn return
interval for controlled burns in H. forbesii habitat ``east of the
Minewawa truck trail on the Otay Mountain [Wilderness]'' (BLM 1994, p.
21). The Minewawa Truck Trail runs from the peak at Doghouse Junction,
north to Otay Lakes Road, dividing the northern half of Otay Mountain
into east and

[[Page 9999]]

west quarters. As discussed above, per an MOU, BLM has committed to
manage its lands in a manner that complements the County of San Diego
Subarea Plan; this management commitment was mistakenly attributed to
that HCP in the 90-day finding. The 48-ac (19-ha) estimate was based on
the area of H. forbesii stands mapped by Lucas (Forister and Lucas
2009, pp. 1-2) and located outside the Otay Mountain Wilderness.
Therefore, the 48-ac (19-ha) area estimate is not accurate with regard
to the amount of H. forbesii habitat (see Distribution and Population
Status section above) that is managed by the County of San Diego. Our
estimate of the habitat managed by the County of San Diego under their
subarea plan is 859 ac (348 ha) (see discussion above). Finally, BLM
does not have any plans to conduct controlled burns (see Factor D
discussion below) nor is it committed to maintain a 25-year burn return
interval for such burns (BLM 1994, p. 21), and the County of San Diego
Subarea Plan includes the assurance that wildfires will not occur too
frequently in areas where species are sensitive to fire. The BLM draft
revised South Coast Resource Management Plan specifically includes a
goal of restoring burn return interval to 50 years through fire
prevention or suppression and prescribed burns (see Factor D discussion
below). Current BLM prescribed burn practices preclude burning of any
H. forbesii habitat that would not enhance cypress stand viability or
that would negatively affect Thorne's hairstreak butterfly (see Factor
D discussion below). Therefore, the misrepresented regulatory 25-year
burn return interval issue is not a valid concern with regard to
Thorne's hairstreak butterfly conservation.
The City of Chula Vista Subarea Plan under the MSCP includes a
preserve that encompasses the newly discovered Otay River Valley
occupied site (see Distribution and Population Status section above).
Thorne's hairstreak butterfly and Hesperocyparis forbesii are not
covered species under this subarea plan. However, all lands preserved
under the Chula Vista Subarea Plan are adaptively managed and
maintained to:
(1) Ensure the long-term viability and sustainability of native
ecosystem function and natural processes throughout the Preserve;
(2) Protect existing and restored biological resources from the
impacts of human activities within the Preserve while accommodating
compatible uses;
(3) Enhance and restore, where feasible, appropriate native plant
associations and wildlife connections to adjoining habitat to provide
viable wildlife and sensitive species habitat;
(4) Facilitate monitoring of selected target species, habitats, and
linkages to ensure long-term persistence of viable populations of
priority plant and animal species; and
(5) Ensure functional habitats and linkages for those species
(Service 2003b, pp.18, 70, FWS-SDG-882.1).
We believe these management prescriptions adequately protect
Thorne's hairstreak butterfly and its habitat within the preserve, and
the adaptive management measures of the Chula Vista Subarea Plan allow
for adjustment of preserve management, as appropriate, to conserve this
newly discovered population of Thorne's hairstreak butterfly.
One relatively small area of occupied cypress forest (approximately
60 ac (24 ha) composed of four butterfly observation locations) in the
southwest foothills of Otay Mountain east of Otay Mesa is privately
owned and not within an approved subarea plan, but falls within the
MSCP planning area where a new subarea plan is being developed (i.e., a
County of San Diego MSCP ``Amendment Area'') (CNDDB GIS Database 2010).
While these habitats are not currently protected from threats to
Thorne's hairstreak butterfly habitat by conservation or management,
the majority of this area is also occupied by the endangered Quino
checkerspot butterfly (Euphydryas editha quino), and Thorne's
hairstreak butterfly habitat is therefore already afforded some
indirect protection under section 9 of the Act.
Summary of Factor A
We evaluated several factors with the potential to destroy, modify,
or curtail Thorne's hairstreak butterfly's habitat or range, including
decreasing burn return intervals, climate change related to wildfire,
habitat fragmentation, and road and firebreak construction. We also
evaluated the benefits to Thorne's hairstreak butterfly and its habitat
associated with HCPs and NCCPs. Wildfire can negatively affect the
species' habitat and in particular its host plant. However, our
analysis does not indicate wildfire events have deviated from
historical fire frequency or burn return interval patterns. Despite two
recent large fires (2003 and 2007), Thorne's hairstreak butterfly has
not only survived or recolonized habitats within mapped recent fire
perimeters, it has expanded its range. In addition, while uncertainty
exists regarding the potential effects of climate change on wildfire
and habitat loss, the best available information regarding decreased
burn return interval indicates the indirect effects of climate change
on Thorne's hairstreak butterfly habitat are not threats to the
subspecies now, nor are they predicted for the future. We have also
determined the best available information indicates habitat
fragmentation does not occur within the range of Thorne's hairstreak
butterfly. We further determined that impacts to Thorne's hairstreak
butterfly habitat resulting from road and firebreak construction have
been relatively limited and are not anticipated to increase in the
future. Additionally, approximately 99 percent of all potential
Thorne's hairstreak butterfly habitat (cypress woodland within existing
County of San Diego Subarea Plan preserves, the City of Chula Vista
Subarea Plan preserve, and Otay Mountain Wilderness Area) is conserved
and managed to benefit both the species and its host plant. Therefore,
we believe existing HCPs and NCCPs provide protection for Thorne's
hairstreak butterfly habitat. Based on our review of the best available
scientific and commercial information, we conclude that Thorne's
hairstreak butterfly is not threatened by the present or threatened
destruction, modification, or curtailment of its habitat or range now
or in the foreseeable future.

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

We have no information to indicate that overutilization for
commercial, recreational, scientific, or educational purposes is
currently a threat to the Thorne's hairstreak butterfly, nor do we
anticipate that it will become a threat in the future. Therefore, based
on our review of the best available scientific and commercial
information, we conclude that Thorne's hairstreak butterfly is not
threatened by overutilization for commercial, recreational, scientific,
or educational purposes now or in the foreseeable future.

Factor C. Disease or Predation

Disease
Our review of the best available scientific and commercial data
found nothing to indicate that disease is a threat to Thorne's
hairstreak butterfly now or in the foreseeable future.
Predation
Predation (including parasitism) is a factor that is known to cause
mortality in butterflies, and therefore could potentially threaten any
butterfly

[[Page 10000]]

species. Faulkner and Klein (2005, p. 34) stated that birds may consume
Thorne's hairstreak butterfly larvae, although we are not aware of any
data that indicate bird predation is a significant threat to Thorne's
hairstreak butterflies. Brachonid wasps (parasitoid insects that
deposit eggs in their host and kill it when offspring emerge as adults)
have been observed near the host plant, but there has been no
documentation of predation on Thorne's hairstreak butterflies (Faulkner
and Klein 2005, p. 34; Klein 2010a p, 5). One potential larval predator
observed during the 2007 season in large numbers at one occupied site
is the nonnative seven-spotted ladybird beetle (Coccinella
septempuctata) (Klein 2010a, pp. 5, 12); however, we are not aware of
any data indicating the beetles have negative effects on Thorne's
hairstreak butterfly.
Heavy predation and parasitism of adult insects and their progeny
is a common ecological phenomenon, and most species have evolved under
conditions where high mortality due to natural enemies has shaped their
evolution (see Schmid-Hempel 1995, p. 255; Ehrlich et al. 1998). Our
review did not reveal any specific information regarding predation of
Thorne's hairstreak butterflies, nor do we have any indication that
predation will become a threat in the foreseeable future. Therefore,
based on our review of the best available scientific and commercial
information, we conclude Thorne's hairstreak butterfly is not
threatened by predation either now or in the foreseeable future.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

The Act requires us to examine the adequacy of existing regulatory
mechanisms with respect to threats that may place Thorne's hairstreak
butterfly in danger of extinction or likely to become so in the future.
Existing regulatory mechanisms that may have an effect on potential
threats to Thorne's hairstreak butterfly can be placed into two general
categories: (1) Federal mechanisms, and (2) State mechanisms.
Federal Mechanisms
The Otay Mountain Wilderness Act (1999) (Pub. L. 106-145) and BLM
management policies provide protection for the majority of occupied
Thorne's hairstreak butterfly habitat (over 90 percent of all recorded
butterfly observation locations). The Otay Mountain Wilderness Act
directs that the Otay Mountain designated wilderness area (i.e., Otay
Mountain Wilderness; 18,500 ac (7,486 ha)) be managed in accordance
with the provisions of the Wilderness Act of 1964 (16 U.S.C. 1131 et
seq.). The Wilderness Act of 1964 strictly limits use of wilderness
areas, imposing restrictions on vehicle use, new developments,
chainsaws, mountain bikes, leasing, and mining, in order to protect the
natural habitats of the areas, maintain species diversity, and enhance
biological values. Lands acquired by BLM within the Otay Mountain
Wilderness boundaries become part of the designated wilderness area and
are managed in accordance with all provisions of the Wilderness Act and
applicable laws (for additional information on applicable laws and
management of the Otay Mountain Wilderness, see discussions below).
Thorne's hairstreak butterfly is a BLM-designated sensitive species
(BLM 2010b, p. 3). BLM-designated sensitive species are those species
requiring special management consideration to promote their
conservation and reduce the likelihood and need for future listing
under the Act. This status makes Thorne's hairstreak butterfly
conservation a management priority in the Otay Mountain Wilderness (see
BLM 2008, p. 6).
Fire management activities occur on Otay Mountain as part of the
BLM's current (1994) South Coast Resource Management Plan. Available
information provided by BLM summarizes these ongoing management actions
(Howe 2010, p. 1):
(a) The California Department of Forestry and Fire Protection (CAL
FIRE) San Diego Unit is under a contractual agreement to provide fire
suppression services to BLM-administered Public Lands in San Diego
County;
(b) Planned fire dispatch for the Otay Mountains Wilderness is five
engines, two handcrews, two tanker airplanes, two to three water-drop
helicopters, and assorted command and support personnel;
(c) BLM Fire Management provides an Initial Attack Dispatch and
Agency Representative to ensure appropriate actions are taken on a fire
incident;
(d) On large incidents, several Resource Specialists may form a
team to evaluate fire and fire suppression effects. If a determination
is made to pursue fire restoration and repair, these specialists would
work with Burned Area Emergency Response (BAER) Teams to implement
appropriate actions;
(e) Fire Prevention and Law Enforcement patrols occur on Otay
Mountain, and the Lyons Peak Lookout Tower (north of the Otay Mountain
Wilderness) will reopen to facilitate early fire detection as soon as
funding allows (Allison 2011, p. 1); and
(f) The International Fuelbreak is under a Right-of-Way Agreement
with CAL FIRE.
At some point in the future on an as-needed basis, additional brush
clearing and other fuels modifications, including burning, may occur;
however, no plans exist to perform prescribed burns in groves of
Hesperocyparis forbesii at this time. Any prescribed burning in the
future within the Otay Mountain Wilderness would be designed to promote
conservation of Thorne's hairstreak butterfly and reduce the likelihood
and need for future listing of the subspecies under the Act (see above
discussion of BLM-designated sensitive species for more information).
Specifically, any future prescribed burns in cypress forest would be
limited to low-level understory burns designed to minimize impacts to
H. forbesii and would only occur where mature trees have reached
maximum cone production and burning would likely increase stand
viability (Allison 2011, p. 1). Currently, all cypress stands on Otay
Mountain are within fire perimeters mapped over the past 10 years;
however, there is one approximately 97-ac (39-ha) stand near the peak
that is approximately 40 years old, where burning could be prescribed
if wildfire does not burn it within the next 10 to 15 years (Allison
2011, p. 1).
We believe the current management regime undertaken by BLM under
the existing plan is adequate to protect the subspecies and its habitat
from threats. However, BLM is collaborating with the Service to revise
the South Coast Resource Management Plan, which covers the Otay
Mountain Wilderness. In the current draft revised plan, Thorne's
hairstreak butterfly and Hesperocyparis forbesii are identified as
sensitive species (BLM 2009, p. 3-59), and the plan specifically states
the management of these species and their habitats are important
because of their close association and the importance of fire cycles to
their continued existence. Moreover, one of BLM's primary objectives in
the draft revised plan is improved fire management and collaboration
with local communities and agencies to prevent wildfires. The draft
revised plan specifically includes a goal of restoring fire frequency
to 50 years through fire prevention or suppression and prescribed
burns; once an area has not burned for 50 years the plan allows for
annual prescribed burning of up to 500 ac (202 ha) in the Otay Mountain
Wilderness (BLM 2009, pp. 4-171-4-172). Actions implemented under the
revised plan,

[[Page 10001]]

when final, will be designed to promote conservation of Thorne's
hairstreak butterfly and its habitat.
State Mechanisms
The California Environmental Quality Act (CEQA) requires review of
any project that is undertaken, funded, or permitted by the State or a
local governmental agency. If significant environmental effects are
identified, the lead agency has the option of requiring mitigation
through changes in the project or deciding that overriding
considerations make mitigation infeasible (CEQA section 21002).
Therefore, protection of sensitive native species through CEQA is
dependent upon the discretion of the lead agency involved. The
implementation of CEQA encourages protection of Thorne's hairstreak
butterfly and Hesperocyparis forbesii where projects are undertaken,
funded, or permitted by the State or a local governmental agency
outside of the Otay Mountain Wilderness, and by CAL FIRE within the
wilderness area.
Summary of Factor D
We considered the adequacy of existing regulatory mechanisms to
protect Thorne's hairstreak butterfly. The majority (approximately 90
percent) of potential Thorne's hairstreak butterfly habitat is within
the BLM Otay Mountain Wilderness, and is conserved and managed to
benefit both the species and its host plant. With regard to wildfire in
the Otay Mountain Wilderness: (1) Prevention activities are already a
focus of management and occur regularly; (2) suppression activities are
already a focus of management and occur promptly; and (3) if fire is
not frequent enough to reduce fuel load, prescribed burns can occur.
Therefore, we believe existing regulatory mechanisms already provide
ample regulatory protection of Thorne's hairstreak butterfly from the
potential threat of wildfire (see Factor A above for a discussion of
wildfire). Based on our review of the best available scientific and
commercial information, we conclude Thorne's hairstreak butterfly is
not threatened by the inadequacy of existing regulatory mechanisms now,
nor is it likely to become so in the foreseeable future.

Factor E. Other Natural or Manmade Factors Affecting The Species'
Continued Existence

Natural and manmade threats to the Thorne's hairstreak butterfly
include wildfire, small population size, and climate change. Wildfire
is briefly discussed under this factor, and wildfire and climate change
related to wildfire are discussed in detail under Factor A discussion
above. The 90-day finding (75 FR 17062; April 5, 2010) also indicated
that grazing and population fragmentation were potential threats to the
subspecies. In the development of this 12-month finding, we further
investigated these potential threats and found that grazing does not
currently occur on Otay Mountain, nor is it planned for the future
(Doran 2010, p. 1; Ford 2010, p. 1; Schlachter 2010, p. 1); therefore,
it is not a threat to the subspecies at this time, nor is it likely to
become so in the foreseeable future. We also determined that population
fragmentation for Thorne's hairstreak butterfly is dependent on habitat
fragmentation, which is discussed above under Factor A, and is not a
threat to the species at this time or in the foreseeable future.
Wildfire
As discussed under Factor A above, wildfire can be a risk factor
for Thorne's hairstreak butterfly and its host plant and nectar
sources. However, as discussed above under Factor D, existing fire
prevention and suppression activities are already in place to minimize
the impacts of fire on this species to the maximum extent practicable,
and measures are being taken to improve such activities. Although
Thorne's hairstreak butterflies can be killed by wildfire, the best
available information indicates Thorne's hairstreak butterfly habitat
is relatively resilient and can re-colonize areas after fire events.
Small Population Size
Although we do not have data from which to draw conclusions
regarding Thorne's hairstreak butterfly population size, we nonetheless
considered whether rarity might pose a potential threat to the species.
While small populations are generally at greater risk of extirpation
from normal population fluctuations due to predation, disease, changing
food supply, and stochastic (random) events such as fire, corroborating
information regarding threats beyond rarity is needed to meet the
information threshold indicating that the species may warrant listing.
In the absence of information identifying threats to the species and
linking those threats to the rarity of the species, the Service does
not consider rarity alone to be a threat. Further, a species that has
always had small population sizes or has always been rare, yet
continues to survive, could be well-equipped to continue to exist into
the future.
Many naturally rare species have persisted for long periods within
small geographic areas, and many naturally rare species exhibit traits
that allow them to persist despite their small population sizes.
Consequently, the fact that a species is rare or has small populations
does not necessarily indicate that it may be in danger of extinction
now or in the foreseeable future. We need to consider specific
potential threats that might be exacerbated by rarity or small
population size. Although low genetic variability and reduced fitness
from inbreeding could occur, at this time we have no evidence of
genetic problems with the Thorne's hairstreak butterfly. Based on the
available information, and the fact that Thorne's hairstreak butterfly
has survived for an unknown number of years, we conclude that genetic
variability and reduced fitness are not imminent threats now, nor do we
believe they will become threats in the foreseeable future. Although we
have only known of its existence since 1972 (Brown 1983, p. 246),
Thorne's hairstreak butterfly has always been endemic to Otay Mountain
(Brown 1983; Beztler et al. 2003; Faulkner and Klein 2005) and has
historically survived fires, drought, and other stochastic events.
Therefore, we have no data to indicate that rarity or small population
size, in and of themselves, pose a threat to the subspecies at this
time or in the foreseeable future.
Climate Change
Downscaled local climate model predictions for Thorne's hairstreak
butterfly range indicate a warmer, drier climate in the vicinity of
Otay Mountain (downscaled resolution corresponds to the area of Otay
Mountain; The Nature Conservancy Climate Wizard 2010). Climate Wizard
(The Nature Conservancy 2010) model calculations and predictions for
Otay Mountain indicate that the average annual temperature has
increased approximately 0.06 degrees Fahrenheit ([deg]F) (0.03 degrees
Celsius ([deg]C)) per year for the past 50 years (p>.001), will likely
increase another 5 [deg]F (2.8 [deg]C) in the next 40 years (medium and
high scenarios), and will increase another 6.5 to 7.5 [deg]F (3.6 to
4.2 [deg]C) within the next 70 years (medium and high scenarios). Otay
Mountain average annual precipitation has decreased 0 to 0.1 percent
per year over the past 50 years (p=1), is predicted to decrease by up
to 7 percent over the next 40 years, and is predicted to decrease by up
to 12 to 13 percent over the next 70 years (medium and high scenarios;
The Nature Conservancy Climate Wizard 2010). These environmental
factors are the primary driver of (similar but likely at a greater

[[Page 10002]]

scale) models that predict increased fire frequency and scope, and
possible Hesperocyparis forbesii population decline (see Factor A
discussion above). However, the models are general and do not enable us
to conclude that host plant populations would decline significantly or
to predict a decrease of the specific host plants used by Thorne's
hairstreak butterfly. It is not clear how predicted environmental
changes would directly affect Thorne's hairstreak butterfly and its
habitat (i.e., the H. forbesii) due to the uncertainty of the models.
We are unable to estimate any direct climate change effects to Thorne's
hairstreak butterfly populations because the climate tolerances of
Thorne's hairstreak butterfly are unknown, although they seem to do
well at all climate extremes within their current range (all
elevations). Because we believe the available modeling information on a
potential decrease in the H. forbesii population (as described above)
is too general to be a reliable source to predict changes in the
Thorne's hairstreak butterfly population, we are relying on the ecology
of the host plant and Zedler (2010) to help us ascertain the likelihood
of the loss of the host plant and thus Thorne's hairstreak butterfly.
Specifically (and as described in the Wildfire and Climate Change
Related to Wildfire section above), Zedler (2010b, p. 2) concluded that
it is unlikely the species would be extirpated in 100 years in part
because the statistical probability of H. forbesii being extirpated
from Otay Mountain is very low or insignificant. Therefore, the
Thorne's hairstreak butterfly's distribution seems currently, and
likely to remain limited by the distribution of its host plant rather
than climate. Thus there is no indication that changes in climate would
affect the distribution of Thorne's hairstreak butterfly. Unlike models
used to predict vegetation changes (such as those described above under
Factor A), no niche models or similar analyses have been conducted to
determine potential direct (climate suitability) or indirect effects
(effects of climate on habitat suitability) to the butterfly.
Therefore, available data is not adequate to evaluate the potential
direct effects of predicted climate changes on Thorne's hairstreak
butterfly or to indicate that the species is currently in danger of
extinction now or in the foreseeable future.
Based on a review of the best available scientific and commercial
data regarding wildfire, small population size, and climate change, we
found no reliable evidence that other natural or manmade factors
affecting the continued existence of the Thorne's hairstreak butterfly
are a threat to the subspecies either now or in the foreseeable future.

Summary of the Five Factors

This status review found no significant threats to Thorne's
hairstreak butterfly related to Factors A, B, C, D, or E, as described
above.
We find that the best available information for Factor A, including
information on the potential effects of wildfire, climate change
related to wildfire, habitat fragmentation, and road and firebreak
construction, and the beneficial effects of HCPs and NCCPs, indicates
that Thorne's hairstreak butterfly is not threatened by the present or
threatened destruction, modification, or curtailment of its habitat or
range. Analysis of historical fire patterns on Otay Mountain and
recolonization of habitat following fire indicate wildfire and road and
fire break construction has not fragmented or reduced habitat in
occupied areas. While uncertainty exists regarding the potential
effects of climate change on wildfire and habitat loss, the best
available information regarding decreased burn return interval
indicates this is not a significant threat to the subspecies.
Furthermore, habitat conservation plans (HCPs) and natural community
conservation plans (NCCPs) benefit Thorne's hairstreak butterfly,
Hesperocyparis forbesii, and their habitat through conservation,
management, and preservation.
The available information concerning overutilization (Factor B) and
predation (Factor C) does not indicate that the Thorne's hairstreak
butterfly is threatened by these factors. We find that the best
available information concerning Factor D (Inadequacy of Existing
Regulatory Mechanisms) indicates that the Thorne's hairstreak butterfly
is not threatened by the inadequacy of existing regulations.
Finally, we find that the best available information concerning
Factor E (Other Natural or Manmade Factors Affecting the Species'
Continued Existence) indicates that the Thorne's hairstreak butterfly
is not threatened individually or cumulatively by the effects of
wildfire, small population size, or climate change. Post-fire surveys
indicate Thorne's hairstreak butterflies recolonized all habitat
affected by large fires in 2003 and 2007 that had previously been
documented to be occupied (this excluded the recently discovered stand
within the City of Chula Vista Subarea Plan because it was discovered
after the fires), indicating that the butterfly is not restricted to
isolated patches. Additionally, available data do not suggest that
rarity or small population size, in and of themselves, pose a threat to
the subspecies at this time or in the foreseeable future.

Finding

As required by the Act, we conducted a review of the status of the
Thorne's hairstreak butterfly and considered the five factors in
assessing whether the Thorne's hairstreak butterfly is in danger of
extinction or likely to become so in the foreseeable future throughout
all or a significant portion of its range. We examined the best
scientific and commercial information available regarding the past,
present, and future threats faced by the Thorne's hairstreak butterfly.
We reviewed the petition, information available in our files, and other
available published and unpublished information, and we consulted with
experts knowledgeable about Thorne's hairstreak butterfly, habitat
experts, and representatives from the BLM and local jurisdictions.
During our status review for this species, it has become evident
that many threat issues are speculative or are associated with
predicted future climate changes, with no historical or current
documented direct impacts to the species or its habitat relating to
these issues. Our review of the best available scientific and
commercial information pertaining to the five threat factors does not
support a conclusion that there are independent or cumulative threats
of sufficient imminence, intensity, or magnitude to indicate that
Thorne's hairstreak butterfly is in danger of extinction (endangered),
or likely to become endangered within the foreseeable future
(threatened), throughout its range. Therefore, we have determined that
the Thorne's hairstreak butterfly does not meet the definition of an
endangered species or a threatened species under the Act and, as a
result, does not warrant listing under the Act at this time.

Significant Portion of the Range

Having determined that Thorne's hairstreak butterfly does not meet
the definition of an endangered or a threatened species, we must next
consider whether there are any significant portions of the range where
Thorne's hairstreak butterfly is in danger of extinction or is likely
to become endangered in the foreseeable future.
On the basis of our review, we found no geographic concentration of
threats either on public or private lands to suggest that Thorne's
hairstreak

[[Page 10003]]

butterfly may be in danger of extinction in that portion of its range.
We found no area within the range of Thorne's hairstreak butterfly
where the potential threats are significantly concentrated or
substantially greater than in other portions of the range. Therefore,
we find factors affecting the subspecies are essentially uniform
throughout its range, indicating no portion of the butterfly's range
warrants further consideration of possible endangered or threatened
status under the Act.
We find that the Thorne's hairstreak butterfly is not in danger of
extinction now, nor is it likely to become endangered within the
foreseeable future, throughout all or a significant portion of its
range. Therefore, listing the Thorne's hairstreak butterfly as
endangered or threatened under the Act is not warranted at this time.
We request that you submit any new information concerning the
status of, or threats to, the Thorne's hairstreak butterfly to our
Carlsbad Fish and Wildlife Office (see ADDRESSES section) whenever it
becomes available. New information will help us monitor the Thorne's
hairstreak butterfly and encourage management of this subspecies and
its habitat. If an emergency situation develops for the Thorne's
hairstreak butterfly or any other species, we will act to provide
immediate protection.

References Cited

A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Carlsbad Fish and
Wildlife Office (see ADDRESSES section).

Authors

The primary authors of this notice are the staff members of the
Carlsbad Fish and Wildlife Office.

Authority

The authority for this section is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

Dated: February 10, 2011.
Rowan W. Gould,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2011-4038 Filed 2-22-11; 8:45 am]
BILLING CODE 4310-55-P