Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Bay Checkerspot Butterfly (Euphydryas editha bayensis, 50406-50452 [E8-19195]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 73, Number 166 (Tuesday, August 26, 2008)]
[Rules and Regulations]
[Pages 50406-50452]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-19195]



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Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Designation of Critical 
Habitat for the Bay Checkerspot Butterfly (Euphydryas editha bayensis); 
Final Rule

Federal Register / Vol. 73, No. 166 / Tuesday, August 26, 2008 / Rules and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R8-ES-2008-0034; 92210-1117-0000-B4]
RIN 1018-AV24


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for the Bay Checkerspot Butterfly (Euphydryas editha 
bayensis)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are 
designating revised critical habitat for the Bay checkerspot butterfly 
(Euphydryas editha bayensis) under the Endangered Species Act of 1973, 
as amended (Act). In total, approximately 18,293 acres (ac) (7,403 
hectares (ha)) fall within the boundaries of the revised critical 
habitat designation for the Bay checkerspot butterfly. The revision to 
critical habitat is located in San Mateo and Santa Clara Counties, 
California. This final revised designation therefore constitutes a 
reduction of 1,453 ac (588 ha) from our 19,746 ac (7,990 ha) proposed 
revised designation of critical habitat for the Bay checkerspot 
butterfly published on August 22, 2007.

DATES: This rule becomes effective on September 25, 2008.

ADDRESSES: The final rule, final economic analysis, and map of critical 
habitat will be available on the Internet at https://www.regulations.gov 
and https://www.fws.gov/sacramento. Comments and materials received, as 
well as supporting documentation used in the preparation of this final 
rule, are available for public inspection, by appointment, during 
normal business hours, at the Sacramento Fish and Wildlife Office, 2800 
Cottage Way, Suite W-2605, Sacramento, CA 95825; telephone 916-414-
6600.

FOR FURTHER INFORMATION CONTACT: Field Supervisor, Sacramento Fish and 
Wildlife Office, 2800 Cottage Way, Room W-2605, Sacramento, CA 95825; 
telephone 916-414-6600; facsimile 916-414-6712. If you use a 
telecommunications device for the deaf (TDD), call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

    This final rule addresses revised critical habitat for the Bay 
checkerspot butterfly. For additional information on the taxonomy, 
biology, and ecology of the Bay checkerspot butterfly, refer to the 
final listing rule and revised proposed critical habitat rule published 
in the Federal Register on September 18, 1987 (52 FR 35366) and August 
22, 2007 (72 FR 48178), respectively. It is our intention to discuss 
only those topics directly relevant to the revised designation of 
critical habitat in this final rule.

Previous Federal Actions

    On April 30, 2001 (66 FR 21450), we published a final rule 
designating approximately 23,903 ac (9,673 ha) of critical habitat for 
the Bay checkerspot butterfly in San Mateo and Santa Clara Counties, 
California. On March 30, 2005, the Home Builders Association of 
Northern California filed suit against the Service challenging critical 
habitat for the Bay checkerspot butterfly and other species (Home 
Builders Association of Northern California v. U.S. Fish and Wildlife 
Service cv-01363-LKK-JFM.). On February 24, 2006, a settlement 
agreement was reached that requires the Service to reevaluate the final 
critical habitat rule in light of the standards for designating 
critical habitat set forth in Home Builders Association of Northern 
California v. U.S. Fish and Wildlife Service, 268 F. Supp. 2d 1197 
(E.D. Cal 2002) and any applicable law. In addition, the settlement 
stipulated that a revised proposed rule be submitted for publication on 
or before August 14, 2007, and a final revised rule be submitted for 
publication on or before August 14, 2008. This final designation is 
being completed and published in the Federal Register in compliance 
with that settlement agreement. On August 22, 2007 (72 FR 48178), we 
published a revised proposed rule to designate approximately 19,746 ac 
(7,990 ha) in San Mateo and Santa Clara Counties, California. On April 
15, 2008 (73 FR 20237), we published a draft economic analysis (DEA) 
for the proposed rule to revise critical habitat.

Summary of Comments and Recommendations

    We requested written comments from the public on the proposed rule 
to revise critical habitat for the Bay checkerspot butterfly and the 
associated DEA. During the comment period, we requested all interested 
parties to submit comments or information related to the proposed 
revision to the critical habitat designation, including, but not 
limited to, the following: information regarding dispersal areas, 
species occurrence information (specifically recent occupancy of the 
Pulgas Ridge Unit) and distribution, land use designations that may 
affect critical habitat, potential economic effects of the proposed 
designation, benefits associated with critical habitat designation, 
areas considered for exclusion, and the inclusion of water sources as a 
primary constituent element (PCE).
    We also contacted appropriate Federal, State, and local agencies; 
scientific organizations; and other interested parties and invited them 
to comment on the revised proposed rule and the associated DEA. The 
comment period for the revised proposed rule opened on August 22, 2007, 
and closed on October 22, 2007. During the comment period for the 
revised proposed rule, we received eight comment letters on the 
proposed revised critical habitat designation and DEA: three from peer 
reviewers, two from local governments, and three from organizations or 
individuals. We received no comments from State or Federal agencies. 
The comment period for the DEA opened on April 15, 2008, and closed on 
May 15, 2008. We received two comment letters and no requests for 
public hearings.
    Comments and new information received in response to the revised 
proposed rule that were relevant to the final designation were 
incorporated in the final rule as appropriate and are summarized below.

Peer Review

    In accordance with our policy published on July 1, 1994 (59 FR 
34270), we solicited expert opinions from seven knowledgeable 
individuals with scientific expertise that included familiarity with 
the species, the geographic region in which the species occurs, and 
conservation biology principles. We received responses from three of 
the peer reviewers. The peer reviewers were generally supportive of the 
designation of critical habitat.
    We reviewed all comments received from the peer reviewers and the 
public for substantive issues and new information regarding critical 
habitat for the Bay checkerspot butterfly. All comments received were 
grouped into general issue categories relating to the proposed rule to 
revise critical habitat for the Bay checkerspot butterfly and are 
addressed in the following summary and incorporated into this final 
revised rule as appropriate.

Peer Reviewer Comments

    In general, all three peer reviewers supported the revised critical 
habitat designation. However, two peer reviewers questioned whether 
some

[[Page 50407]]

units were ``critical.'' One peer reviewer stated that the background 
information was comprehensive and reflected the decade's worth of 
research on the butterfly and that the accounts on nitrogen deposition 
and topographic effects are good summaries. One peer reviewer felt that 
using both currently occupied and historically occupied habitats was a 
good inclusive decision and effectively covered any remaining suitable 
habitat. Individual peer comments are listed below.
    Comment 1: One peer review suggested that the designation of 
``primary'' and ``secondary'' host plants implies that eggs are always 
laid on Plantago erecta. The reviewer indicated that their work on the 
Bay checkerspot butterfly suggests that this is true in some places 
such as at Jasper Ridge; however, at Edgewood approximately 70 percent 
of oviposition occurred on Castilleja and that in the 1980s, 
approximately 20 percent of oviposition at Kirby Canyon (the southern 
portion of Coyote Ridge) occurred on Castilleja.
    Our Response: The comment is noted and clarification has been 
provided to indicate that ``primary'' refers to the host plant species 
that is used most frequently for oviposition, although not exclusively. 
Please see the ``Primary Constituent Elements'' section under ``Food'' 
for more information.
    Comment 2: One peer reviewer noted that the evidence for repeat 
diapause is more robust than is noted in the literature. The commenter 
stated that several persons had observed repeat diapause by this 
insect, although he was not aware if larvae were capable of multiyear 
diapause without the opportunity to feed in-between years.
    Our Response: We have added the peer reviewer's personal 
observations of multiple diapauses to this final rule in the ``Primary 
Constituent Elements'' section under ``Cover.''
    Comment 3: One peer reviewer confirmed the use of water or 
``puddling'' behavior described by Launer et al. (1993) in the Bay 
checkerspot butterfly. The peer reviewer also noted having observed 
puddling by both sexes of other Edith's checkerspots (Euphydryas editha 
spp.). However, he also noted that while puddling could extend an 
adult's lifespan, female Bay checkerspot butterflies were still likely 
to be able to lay most of their eggs under dry conditions if they still 
had access to nectar sources.
    A second reviewer stated that while he had documented ``puddling'' 
in the Bay checkerspot butterfly and the use of water was interesting, 
it was not a significant finding. Further, the peer reviewer stated 
that water should not be considered when evaluating habitat quality for 
the Bay checkerspot butterfly.
    A third peer reviewer stated the need for aquatic features is too 
strong and that the Bay checkerspot butterfly will use water when 
needed and available during drought years.
    Our Response: Based on the above comments from peer reviewers, the 
Service has removed aquatic features as a PCE in this final rule. For 
more information, see the ``Primary Constituent Elements'' section of 
this final rule. Because all of the units designated contain all of the 
remaining PCEs identified in the proposed rule, the removal of aquatic 
features as a PCE did not affect the overall designation of critical 
habitat.
    Comment 4: One peer reviewer questioned the utility of providing a 
list of grassland plant species and noted that an attempt to do so 
would likely result in a long list. However, he noted that, if a list 
is to be provided, that Italian ryegrass (Lolium multiflorum) should be 
included.
    Our Response: The Service attempted to provide a list of plant 
species commonly found in open grasslands in California. The list of 
grassland species was not meant to be exhaustive or to represent 
species that the Bay checkerspot butterfly depends on. Since Italian 
ryegrass is commonly found in grasslands in California, the Service 
will add it to the list of species that commonly occur in grassland 
habitats in California.
    Comment 5: One peer reviewer provided the following information 
regarding fire and prescribed burns: (1) Late spring burns reduce 
annual grass and increase native forbs for 1 to 2 years post burn, and 
in Santa Clara County grass reinvades quickly in the absence of grazing 
such that 3 to 4 years post burn the habitat is again dominated by 
annual grass; (2) fall burns reduce grass thatch but are not effective 
in reducing annual grass in subsequent years; (3) diapausing larvae can 
survive fire (in winter of 2007 and 2008, larvae were found in areas 
burned the previous spring and summer); (4) spring fires to control 
barbed goatgrass will be an essential management tool; (5) thatch 
removal by spring and fall burns are effective initially but must be 
followed by grazing to be effective in the long term; and (6) positive 
effects from burns will likely last longer in areas with lower nitrogen 
deposition (San Mateo County).
    Our Response: The Service has incorporated the information provided 
regarding fire (from the Metcalf Center Energy reports CH2M Hill 2005, 
2006, and 2008) into this final rule. Please see the ``Special 
Management Considerations or Protections'' section below for more 
information.
    Comment 6: One peer reviewer provided the following comments 
regarding potential adverse modification of critical habitat: (1) Small 
scale disturbances in serpentine grasslands generally do not pose a 
risk to Bay checkerspot butterfly populations; (2) the section 
regarding short-term mortality from grazing and fire should be 
clarified to state that the negative effects of fire and grazing are 
significantly outweighed by the positive benefit to the Bay checkerspot 
butterfly; (3) removal of grazing provides one of the biggest threats 
to the subspecies; (4) nitrogen disposition is the current greatest 
threat; and (5) pesticides inappropriately applied could cause local 
negative effects.
    Our Response: We have provided clarification in this final rule 
regarding the beneficial effects of grazing and fire to the Bay 
checkerspot butterfly's habitat. Please see the ``Special Management 
Considerations or Protections'' section below for more information.
    Comment 7: One peer reviewer stated that data regarding host plant 
density might be available from The Howard Mooney Lab at Stanford 
University.
    Our Response: The Service attempted to contact researchers with the 
Howard Mooney Lab but did not receive a reply.
    Comment 8: One peer reviewer stated that while he was part of the 
group that promoted the Bay checkerspot butterfly as a metapopulation 
species, much of the information necessary to characterize the species 
as such is not well known. As an example, the peer reviewer stated that 
extinction and recolonization events, rates of long-distance dispersal, 
and the number of individuals required to establish new populations are 
not well known. Finally, the peer reviewer stated that the Bay 
checkerspot butterfly's metapopulation is ``not well known or as 
elucidated as it is sometimes portrayed (Launer 2008 p. 1).''
    Our Response: The Service is aware that the exact nature of the Bay 
checkerspot butterfly's population dynamics is highly complex and that 
long-distance dispersal, extinction or recolonization rates, and the 
threshold of individuals required to establish or re-establish a 
population is not well documented. The Service took a conservative 
approach in designating critical habitat partly because of the lack of 
data available regarding dispersal and recolonization rates. We only 
designated areas that had documented occurrences

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of the Bay checkerspot butterfly. We did not designate all areas within 
the range of the Bay checkerspot butterfly that could support the 
species, partly because of lack of data regarding the dispersal 
capabilities of the subspecies, number of individuals required to 
establish new populations, and the minimum size necessary to support a 
population. For additional information, please see the ``Criteria Used 
to Identify Critical Habitat'' section of this rule. In addition, we 
lacked occurrence data for sites outside those we designated as 
critical habitat; sites that were not occupied at the time of listing 
or since listing did not meet our criteria for designating critical 
habitat.
    Comment 9: One peer reviewer believes that all conservation 
planning in the region (including critical habitat designations) should 
be aware of the unstable nature of the habitat in these areas. The 
conditions present today may not persist into the next quarter and half 
century; this is particularly true of the distribution of the Bay 
checkerspot butterfly and the apparent acceleration of climate change. 
The reviewer also stated that as much topographic diversity and 
geographic range should be included in the designation as possible.
    Our Response: A current trend in conservation biology is the use of 
adaptive management. Adaptive management is a mechanism by which 
resource managers acknowledge the uncertainty of the effects of various 
management actions in addition to the often rapidly changing nature of 
the resource they are trying to manage. The Service is aware of the 
ongoing and often rapid changes in the environment that occur 
throughout the range of the Bay checkerspot butterfly. Because of the 
uncertainty in managing lands in the foreseeable future, many lands 
that have been set aside for the conservation of listed species, 
including the Bay checkerspot butterfly, now include an adaptive 
management component. While the amount of land within individual 
conservation areas is generally static, adaptive management should 
provide resource managers with the framework required to cope with a 
changing landscape. In addition, if the Service determines in the 
future that the designated area no longer meets the definition of 
critical habitat, we will consider proposing a revision to the critical 
habitat designation at that time or when our resources allow.
    Please see the ``Criteria Used to Identify Critical Habitat'' 
section in regards to the comment that topographic diversity and 
geographic range should be included in the designation where possible, 
The Service only designated areas that had documented occurrences of 
the Bay checkerspot butterfly. We did not designate all areas within 
the range of the Bay checkerspot butterfly that could support the 
species, partly because of lack of data regarding the dispersal 
capabilities of the subspecies, number of individuals required to 
establish new populations, and the minimum size necessary to support a 
population.
    Comment 10: One peer reviewer reiterated the fact that Bay 
checkerspot butterfly population levels fluctuate widely from one year 
to the next. In addition, the reviewer stated that while interesting, 
the number of individuals present at a given site in a given year is 
misleading and that multi-year trends are useful in conservation 
planning, but are much less available.
    Our Response: The Service recognizes that the number of individuals 
in a single year does not adequately reflect the overall health of the 
population within a given unit due to the population dynamics of the 
species and its tendency towards wide swings in number of individuals. 
However, when evaluating the population status of a species, it is 
incumbent on the Service to use the best data available. While the 
reviewer correctly pointed out that long multi-year population data for 
this species are not available for many of the units, multi-year 
population trends are available for some of the units (i.e., those 
along Coyote Ridge). In other units, only single year assessments are 
available. Our designation of critical habitat for the Bay checkerspot 
butterfly is based on the best scientific information available.
    Comment 11: One peer reviewer noted that almost all of the units 
include some area of nonserpentine soil and that these areas should 
probably be expanded in several units. The commenter also noted that, 
while these areas of nonserpentine soils do not support host plant 
densities sufficient to support checkerspot larvae, the adults do fly 
through these areas and it is important not to disrupt dispersal 
routes. The peer reviewer noted that while dispersal routes are not 
well documented for the Bay checkerspot butterflies, they are known to 
fly through nonserpentine areas, along ridgelines, and between close 
patches of suitable habitat if intervening habitats have not been 
overly modified.
    Our Response: All units support all the PCEs, although each PCE is 
not evenly distributed throughout each unit. For example, within each 
unit all PCEs are present, but PCE 2 (larval host plants) may only be 
present in scattered patches and the exact distribution of PCE 2 (and 
PCE 3, adult nectar plants) changes from one year to the next. The 
fluctuation in host plant distribution made it impossible to base unit 
boundaries solely on PCE 2 or PCE 3. Larger areas of grassland habitat 
around larval host and adult nectar plants were included within unit 
boundaries, because they support PCEs 1, 3, 4, and 5. Therefore, 
independent of facilitating dispersal between patches of larval host 
and adult nectar plants, grasslands within units provide features 
essential to the conservation of the Bay checkerspot butterfly. As the 
peer reviewer noted, specific dispersal corridors have not been well 
documented (either within units or between units) for the Bay 
checkerspot butterfly. Since exact routes between units are unknown, 
the Service selected units occupied at listing or currently occupied 
with PCEs that were within the known dispersal distance of the species.
    Comment 12: One peer reviewer stated that even though the San Bruno 
Mt. Unit (Unit 1) is potentially a valuable site, very little habitat 
for the species remains (in part due to succession of plant communities 
and continued invasion by nonnative species) in the unit and it is not 
within ``easy butterfly dispersal distance'' (Launer 2008) or other 
recently occupied habitat. In light of this information the peer 
reviewer felt a re-evaluation of what is possible with respect to Bay 
checkerspot butterfly habitat in San Mateo County should be conducted 
and that it is possible attention should focus on the other three units 
in the County.
    A second reviewer stated the current distribution of habitat on San 
Bruno Mt. is poorly known and detailed surveys should be done. The peer 
reviewer also stated that dispersal between the Pulgas Ridge Unit and 
San Bruno Mt. is unlikely and should not be counted on as part of the 
population-metapopulation process. Finally, the peer reviewer stated 
that the exclusion of San Bruno Mt. appeared reasonable, although the 
site should be explored for potential reintroductions.
    Our Response: The Service proposed the San Bruno Mt. Unit (Unit 1) 
for exclusion for several reasons, including: (1) The large distance 
between the unit and the other units in San Mateo County and the lack 
of adequate information regarding suitable intervening habitat; (2) the 
Bay checkerspot butterfly has not been observed on San Bruno Mt. since 
the mid 1980s despite repeated surveys; (3) much of San Bruno Mt. is 
protected under a habitat conservation plan

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(HCP); and (4) Amendment 5 of the San Bruno Mountain Habitat 
Conservation Plan (SBMHCP) would add the Bay checkerspot as a covered 
species and provide an endowment for continued management actions 
within the HCP boundaries. Furthermore, the unit is occupied by the 
endangered Callippe silverspot butterfly (Speyeria callippe callippe), 
endangered Mission blue butterfly (Icaricia icarioides missionensis), 
and the endangered San Bruno elfin (Callophyrs mossii bayensis), and 
management of the unit for these species would likely be the same as 
for the Bay checkerspot butterfly; there would not likely be any 
additional benefits of designating the area as critical habitat for the 
Bay checkerspot butterfly.
    At the time of the publication of the proposed rule, we expected 
Amendment 5 to the SBMHCP, which would include coverage specific to the 
Bay checkerspot butterfly, to have been finalized prior to the 
publication of this final designation of critical habitat. As this 
amendment is not yet finalized as of the writing of the final rule, we 
re-evaluated the proposed exclusion of the SBMHCP from critical habitat 
and determined that not to exclude this area based on the record before 
us. (See ``Application of Section 4(b)(2) of the Act'').
    In addition, we disagree with the peer reviewers that very little 
habitat remains for the Bay checkerspot butterfly on San Bruno Mt. or 
that the distribution of that habitat is unknown. According to the San 
Bruno Mountain Habitat Management Plan (2008 p. VIII-6), the host 
plants for the Bay checkerspot butterfly are still abundant on the 
mountain in isolated patches within and outside the 2001 designation of 
critical habitat.
    Comment 13: One peer reviewer stated that the Pulgas Ridge Unit 
(Unit 2) was marginal habitat, but prior to fragmentation, encroachment 
of surrounding development, and continued invasion by nonnative plant 
species, the unit and surrounding area supported a large population of 
Bay checkerspot butterflies. The peer reviewer also stated that the 
Pulgas Unit, in conjunction with the Edgewood Park Unit (Unit 3) and 
the Jasper Ridge Unit (Unit 4), could be useful as a complex of 
habitat.
    A second peer reviewer stated that little is known about the Pulgas 
Ridge Unit, except that it contains all the PCEs, is extensive, and has 
topography similar to the Edgewood Park Unit. The peer reviewer also 
reiterated his earlier comment that dispersal between Pulgas Ridge and 
San Bruno Mt. was unlikely given the dispersal tendencies of the 
subspecies and the lack of intervening habitat (high level of 
urbanization and lack of grasslands).
    Our Response: The Service is aware that the Pulgas Ridge Unit will 
require restoration and management in order to reduce non-native plant 
species. However, all the units are assumed to require ongoing 
restoration and management activities in order to restore and maintain 
sufficient habitat to support the Bay checkerspot butterfly, primarily 
due to the continued threat of nonnative plant species. The Service 
included the Pulgas Ridge Unit because the unit historically supported 
the subspecies, is in close proximity to the Edgewood Park Unit, where 
the subspecies was reintroduced in early 2007, and because a core 
population outside Santa Clara County is essential to the recovery of 
the subspecies. The viability of a population in San Mateo County is 
dependent on the population being self-sustaining. A single unit in San 
Mateo County is unlikely to support the metapopulation dynamics of the 
species and would likely ultimately fail.
    Comment 14: With regard to the Edgewood Park Unit one peer reviewer 
said it should be viewed as essential to the recovery of the species 
because of its multiple subunits, topographic diversity, and ``ample 
expanse,'' but that the unit will need ongoing restoration to benefit 
the species.
    A second peer reviewer stated that the Edgewood Park Unit was 
correctly identified in the proposed rule as the only potential core 
habitat remaining in San Mateo County, but the unit would need to be 
managed through rotational mowing for the time being. The reviewer also 
said that the reintroduction of the Bay checkerspot butterfly in 2007 
was not as successful as anticipated (likely due to the extremely dry 
conditions in 2007). More precise information regarding the success of 
the introduction will be available after the 2008 flight season.
    Our Response: Because the Edgewood Park Unit was occupied at the 
time of listing and continues to contain the PCEs essential to the 
conservation of the species, we agree with these peer reviewers that 
this unit should be designated as critical habitat.
    Comment 15: One peer reviewer stated that there were two main 
problems with the Jasper Ridge Unit: (1) The serpentine grasslands 
within the biological preserve are relatively small, and (2) the 
preserve is managed by non-intervention. The reviewer also commented 
that the serpentine grassland present within the unit was in general in 
fair condition, with a few smaller sites of excellent quality habitat, 
but they are within a matrix of poor to marginal quality habitat. The 
peer reviewer believed that with active management Units 2, 3, and 4 
could be essential to the recovery of the Bay checkerspot butterfly.
    A second peer reviewer stated that the designation includes all 
suitable Bay checkerspot butterfly habitat within the unit, although it 
also includes surrounding woodlands, chaparral, and nonnative 
grasslands. Regarding dispersal to this unit from the Santa Clara 
County units, the peer reviewer stated the likelihood was extremely 
low.
    Our Response: The Service agrees that the patches of serpentine 
soils within the unit are relatively small. However, the area of 
similar soil types within the unit encompasses the majority of the 
grasslands within the Biological Preserve. The unit supported multiple 
independent populations for several decades and we believe that in 
conjunction with Units 2 and 3, this unit is capable of supporting the 
subspecies again. In addition, we believe the unit is essential to 
maintaining a core population in San Mateo County, partly due to the 
low likelihood that individual Bay checkerspot butterflies would 
disperse from Santa Clara County.
    The Service acknowledges that the primary focus of the Jasper Ridge 
Biological Preserve (JRBP), which encompasses Unit 3, is research and 
the preserve is not currently managed for any species, including 
protection of the Bay checkerspot butterfly; however, according to the 
2004 draft Jasper Ridge Biological Preserve Strategic Plan (JRBP 2008, 
p. 1), species and habitat conservation is being proposed and these 
conservation efforts should be designed to include protection of 
habitat or individual species. Further, most units are not currently 
managed to benefit the Bay checkerspot butterfly, but still provide 
features essential to the conservation of the subspecies; Also, as 
noted above, the Service believes Unit 3 is necessary to support the 
metapopulation dynamics of the subspecies and to maintain a core 
population in San Mateo County independent of the Santa Clara County 
core population.
    Comment 16: One peer reviewer noted that Unit 5 had only recently 
been referred to as ``Coyote Ridge'' and that historically it was known 
by many names. The peer reviewer recommended a more appropriate name 
for the unit be used. In addition, the reviewer stated the entire ridge 
from the northwest corner (Silver Creek Hills) to Anderson Reservoir 
Dam in the southeast, including the nonserpentine areas, is

[[Page 50410]]

essential for the continued persistence of the Bay checkerspot 
butterfly and that without it the subspecies would cease to exist. The 
reviewer supported the designation of this unit as critical habitat. 
The reviewer also believed that the unit should be expanded to include 
all nonserpentine areas along the ridge and an adequate buffer along 
the sides of the ridge.
    The peer reviewer also noted there are likely more than four 
populations on Coyote Ridge 5 as indicated in the proposed rule and 
that the four mentioned represent the centers of classic study areas, 
but that multiple subpopulations or populations exist in each of the 
four historical centers.
    A second peer reviewer also stated the unit was ``absolutely 
essential'' to the persistence of the Bay checkerspot butterfly. In 
addition, the reviewer believed the unit could be separated into 
multiple units, because some areas are separated by several kilometers 
of non-habitat. The reviewer also commented that the reduction in 
numbers of individuals in the Silver Creek population after 1992 was 
the result of removing grazing for a number of years. The reduction of 
the overall unit's population resulted from the combination of a series 
of poor weather and over-population of larvae in key areas, but that 
this likely represents natural fluctuations.
    Our Response: The Service recognizes that proposed Unit 5 (final 
Units 5 and 13) has historically been identified by a variety of names, 
several of which were noted in the Recovery Plan for Serpentine Soil 
Species of the San Francisco Bay Area (Service 2001, p. II-178). We 
clarify the naming in this final rule by separating the unit into two 
units, based on a natural break in the habitat between the two. We have 
also added information in the unit descriptions stating that the four 
historical population centers are likely not the only populations that 
occur along the ridge.
    The Service agrees with the peer reviewers regarding the importance 
of the entire ridge line. However, we disagree with one of the peer 
reviewers that additional areas should be designated as a buffer. The 
Service included almost all of the grassland on the southwest portion 
of the ridge up to U.S. Highway 101, with only a few exceptions (where 
there was existing development). On the north side of the ridge, the 
Service included all of the areas with serpentine or serpentine-like 
soils, with the exception of a few areas that were separated from the 
main ridgeline and were not grasslands (they were other habitat types). 
We did not include certain areas on the north side of the ridge, as 
explained below, based on specific information we received during 
preparation of the 2001 final critical habitat rule (i.e., information 
regarding lands owned by United Technology Corporation) as well as from 
numerous site visits to this unit.
    We did not include grassland areas on nonserpentine or similar 
soils on the north side of the ridge because we believe these areas 
lack sufficient PCEs to support the Bay checkerspot butterfly. The Act 
defines critical habitat as (1) the specific areas within the 
geographic area occupied by a species, at the time of listing in 
accordance with the Act, on which are found those physical or 
biological features (a) essential to the conservation of the species 
and (b) that may require special management considerations or 
protection; and (2) specific areas outside the geographic area occupied 
by a species at the time it is listed in accordance with section 4 of 
the Act, upon a determination by the Secretary that such areas are 
essential for the conservation of the species. Buffer areas may serve 
to protect critical habitat units from encroachment by development, but 
these lands do not contain PCEs laid out in the appropriate quantity 
and spatial arrangement for the conservation of the species and 
therefore do not meet the regulatory definition of occupied critical 
habitat, nor have we concluded that such unoccupied buffer lands are 
essential to the conservation of the species. In addition, buffers were 
not a criterion used to designate critical habitat for the Bay 
checkerspot butterfly.
    Comment 17: One peer reviewer stated that the Tulare Hill Unit 
(Unit 6) is valuable and provides a natural location for between ridge 
dispersal and he supported designation of the unit as critical habitat. 
In addition, the commenter stated that while habitat quality within the 
unit declined in the 1980s and 1990s, it has recently improved due to 
increased management and that unit wide management should be 
undertaken.
    A second peer reviewer identified this unit as a key link across 
the Santa Clara Valley and its value in previous assessments has been 
underemphasized. The reviewer stated that, if managed properly, the 
unit would support a population in the thousands or more; however, 
habitat on the northern portion of the unit has been degraded due to 
lack of grazing, which underscores the importance of an adequate 
grazing plan.
    Our Response: The Service agrees that the Tulare Hill Unit provides 
an essential link between the east and west portions of the valley and 
serves as the most likely location for between ridge transfers of the 
Bay checkerspot butterfly. Without this unit Bay checkerspot 
butterflies' between-ridge movements are still possible, but would 
likely occur with much lower frequency. For species with a 
metapopulation dynamic, the successful colonization or recolonization 
of a site partly depends on the rate of colonization vs. the rate of 
extinction. Colonization must occur more often than extinction events 
for a site to remain occupied. Therefore, the inclusion of the Tulare 
Hill Unit in this final designation of critical habitat is necessary to 
maintain populations on the western side of the valley.
    The northern portion of the Tulare Hill Unit will soon be managed 
to benefit the Bay checkerspot butterfly as a result of the 
finalization of a Safe Harbor Agreement with Pacific Gas and Electric, 
which will enable grazing of the northern portion of the unit; this 
safe harbor agreement is expected to result in an increase in the 
population of Bay checkerspot butterflies within the unit by 
facilitating grazing in the northern portion of the unit, which is not 
currently grazed and only supports low numbers of the subspecies.
    Comment 18: One peer reviewer stated that designation of the Santa 
Teresa Hills Unit (Unit 7) was reasonable, but that an extensive 
management plan would need to be established, since much of the unit is 
within Santa Teresa County Park and has not been managed for the 
benefit of the Bay checkerspot butterfly. In addition, the peer 
reviewer stated that with proper management this unit could 
significantly contribute to the recovery of the subspecies. The peer 
reviewer made similar comments regarding the Calero Reservoir Unit 
(Unit 8) with the additional comment that the unit's location, its 
topographic diversity, and large size make the unit very valuable for 
long-term conservation of the Bay checkerspot butterfly.
    A second peer reviewer stated the Calero Reservoir Unit (Unit 8) 
has high potential because of its topographic diversity and large size, 
but that occupancy is unclear (according to casual surveys) as the 
habitat has been degraded due to lack of grazing, although effects from 
air pollution may be somewhat less than areas to the east. In addition, 
the reviewer stated that emphasis should be on the serpentine grassland 
and it should be made clear effects of activities outside of these 
grasslands are only a small concern.

[[Page 50411]]

    Our Response: The Service agrees that the Santa Teresa Hills Unit 
(Unit 7) will require restoration and management in order to reduce 
non-native plant species. However, as noted above, all the units are 
assumed to require ongoing restoration activities in order to restore 
and maintain adequate habitat to support the Bay checkerspot butterfly 
over time, due to the continued threat of nonnative plant species.
    The Service does not completely agree with the peer reviewer who 
commented that effects to nonserpentine grasslands are of minor 
concern. Nonserpentine grasslands within a unit between serpentine and 
serpentine-like grasslands likely play an important role in dispersal 
of adult butterflies from one habitat patch to another. Development in 
intervening nonserpentine areas within a unit will likely reduce 
movement of adults between more suitable patches. However, based on the 
peer reviewer's comments, we have revised the northwestern portion of 
the unit boundary. Much of the area removed was heavily interspersed 
with woodland habitat and did not support many of the PCEs, such as the 
presence of serpentine or serpentine-like grasslands.
    Comment 19: One peer reviewer stated that the series of small hills 
that make up the Kalana Hills Unit (Unit 9A and 9B) individually are 
not valuable to the subspecies; however, along with the intervening 
nonserpentine grasslands, they provide a significant resource for the 
Bay checkerspot butterfly. The peer reviewer supported the unit's 
inclusion as critical habitat. The peer reviewer recommended inclusion 
of more of the nonserpentine areas between the units.
    A second peer reviewer stated that the unit was well described and 
the four small serpentine outcrops can be regularly occupied.
    Our Response: The Service did not include all of the intervening 
nonserpentine areas between the large hill (subunit A) and the three 
smaller hills (subunit B) because they are separated by a disked 
agricultural field, which does not support the PCEs and does not meet 
our criteria for designating critical habitat. We did not include all 
areas between each of the three smaller hills because they are 
separated by a small network of local and private roads and at least 
two residences and do not support PCE 1, 2, 3, or 5. We did revise the 
unit boundaries slightly to reflect better resolution from vegetation 
data.
    Comment 20: One peer reviewer stated that the Morgan Hill Unit 
(Unit 10) has historically been referred to as Hale or Falcon Crest. 
The peer reviewer also noted the unit is extensive and topographically 
diverse and that with proper management the unit is important for the 
long-term conservation of the Bay checkerspot butterfly and the peer 
reviewer supported this unit's inclusion as critical habitat.
    Another peer reviewer commented that this area was one of the most 
important outlying areas from Coyote Ridge.
    Our Response: The Service has renamed Unit 10 from Morgan Hill to 
Hale in order to prevent confusion with final Units 5 and 13 (which 
historically have been referred to as Morgan Hill).
    Comment 21: One peer reviewer stated that the Bear Ranch Unit (Unit 
11) consists of a series of small serpentine grasslands and that, prior 
to their inclusion into the Santa Clara County Parks and Recreation 
system, they were grazed and the habitat was in good condition. The 
reviewer expressed support that Santa Clara County Parks and Recreation 
has continued to graze the site. In addition, the reviewer stated that 
the nonserpentine grasslands between the patches were of great 
important to the Bay checkerspot butterfly at this site, and public 
structures (trails, parking facilities, etc.) should not be located 
between the small patches of serpentine grasslands. However, the peer 
reviewer questioned whether the site should be included as critical 
habitat because overall he believed the site was of less importance 
than the other units in Santa Clara County.
    A second peer reviewer simply noted the unit encompassed the 
serpentine grassland within the park.
    Our Response: We included this unit as critical habitat because it, 
along with Unit 12, represents the two southernmost known occurrences 
of the Bay checkerspot butterfly. As such, we believe they may provide 
an important role in the survival of the subspecies. However, the 
Service did revise this unit based on information obtained from or 
developed for the Santa Clara County HCP to better reflect the known 
distribution of serpentine bunchgrass communities within the unit and 
so as not to include nonserpentine grasslands to the west of the two 
serpentine patches.
    Comment 22: One peer reviewer stated that the San Marin Unit (Unit 
12) should not be considered critical habitat because the unit is too 
small, too hot, and too isolated. In addition, the reviewer stated that 
had development not occurred on the northern portion of the site in the 
1980s and 1990s, the site may still benefit the Bay checkerspot 
butterfly, but that now the site is of marginal value.
    A second peer reviewer also noted that the site may provide little 
value due to its size and current level of development.
    Our Response: The Service requested additional information 
regarding development in this unit, but only one peer reviewer 
responded. The reviewer noted that the development was a series of 
large residential lots in the northern portion of the unit. However, 
based on aerial photographs, there are fewer than 10 residences within 
the northern portion of the unit. Topographic maps show a variety of 
slope aspects (including cool northeast slopes) present within the 
unit. The Service acknowledges the most diverse slopes are primarily 
located in the southern portion of the unit. However, the presence of 
both north and east slopes indicates that the entire unit is not ``too 
hot'' as noted by one of the peer reviewers. It does not appear that 
the current level of development has significantly degraded the overall 
habitat within the unit. In addition, as noted above, we included both 
Unit 12 and Unit 11 because they represent the southernmost known 
occurrences of the subspecies and as such may represent important 
adaptive differences between populations of Bay checkerspots 
butterflies in these units and populations in other units. The criteria 
we used to designate critical habitat were whether the area was 
occupied at listing or since listing and whether the area had 
sufficient PCEs to support a population. The unit was occupied at 
listing and currently supports all the PCEs; therefore it meets the 
criteria for critical habitat.
    Comment 23: One peer reviewer supported non-inclusion of 
Communications Hill (Unit 6 in the 2001 designation) because, since 
development of the quarry, the remaining habitat is too hot and too 
limited.
    Our Response: Multiple surveys have been conducted at 
Communications Hill over the last two decades, including two recent 
surveys by Dr. Richard Arnold in 2000 and 2007. According to Arnold 
(2007, p. 7), approximately half of the areas that supported the 
primary larval host plant in 2000 had been eliminated. Of the sites 
that still supported the primary host plant, most did not support 
either of the two secondary host plants. In addition, adult nectar 
sources were ``almost entirely lacking'' (Arnold 2007, p. 7). We 
believe the information presented in the 2000 and 2007 surveys by Dr. 
Richard Arnold in addition to aerial photographs and vegetation maps

[[Page 50412]]

supports the conclusion that much of Communications Hill has been 
developed and what little habitat remains does not provide PCEs in 
sufficient quantities to meet one or more life history requirements of 
the Bay checkerspot butterfly. In addition, there is only one 
unconfirmed record of a single Bay checkerspot butterfly on 
Communications Hill. Given the lack of confirmed records, the current 
developed state of the area, and lack of many of the PCEs, the area did 
not meet the criteria for designation as critical habitat.

Public Comments

    Comment 24: One commenter recommended adding an area proposed as a 
conservation bank in southern Santa Clara County for inclusion within 
the critical habitat designation and noted that a small portion of the 
conservation bank is located within an area historically documented to 
support Bay checkerspot butterflies.
    Our Response: The proposed conservation bank is located in the 
southern portion of Santa Clara County and is approximately 0.5 miles 
(mi) (0.80 kilometers (km)) southwest of the San Martin Unit. According 
to the commenter, the entire site is 1,685 acres with 43.3 ac (17.52 
ha) of serpentine or serpentine-like grasslands scattered across three 
areas that includes all six PCEs. The Service agrees that portions of 
the proposed bank likely support all the PCEs; however, the overall 
amount of habitat that the butterfly could occupy at the site is low. 
According to the California Natural Diversity Data Base (CNDDB), the 
Bay checkerspot occurrence (CNDDB occurrence 19) that includes a small 
portion of the proposed bank is ``nonspecific'' and includes large 
areas of forest, agriculture, and residential areas (including a golf 
course) that do not support the PCEs. The observation was made by Dr. 
Richard Arnold in 1985, but the exact location is not clear and may 
have been part of the serpentine grasslands within the San Martin Unit.
    The commenter did not provide any information regarding larvae or 
adult surveys at the proposed conservation bank or if any individual 
Bay checkerspot butterflies have been observed at the site. A review of 
the literature indicates that apart from the CNDDB's nonspecific 
occurrence by Dr. Richard Arnold, the site has not been identified as 
supporting Bay checkerspot butterflies in the past. At this time the 
Service has insufficient information regarding the ability of the site 
to support Bay checkerspot butterflies to include it in critical 
habitat.
    Comment 25: Two commenters supported non-inclusion of 
Communications Hill in the revised critical habitat designation. One 
commenter provided additional information in the form of vegetative 
surveys by Dr. Richard Arnold in 2000 and 2007.
    Our Response: According to the information provided by one of the 
commenters, additional surveys have been conducted on Communications 
Hill by Dr. Richard Arnold in 2000 and 2007. According to Arnold (2007 
p. 7) approximately half of the areas that supported the primary larval 
host plant in 2000 had been eliminated. Of the sites that still 
supported the primary host plant, most did not support either of the 
two secondary host plants. In addition, adult nectar sources were 
``almost entirely lacking'' (Arnold 2007, p. 7). We believe the 
information presented by the commenters supports the conclusion that 
much of Communications Hill has been developed and what little habitat 
remains does not provide PCEs in sufficient quantities to meet one or 
more life history requirements of the Bay checkerspot butterfly.
    Comment 26: One commenter stated that based on their evaluation of 
their property within the Metcalf Unit (northern portion of proposed 
Unit 5; final Unit 4) that large portions of the site do not include 
serpentine soils or any of the known host plants for the species. 
Furthermore the commenter stated that the soils appear to be thicker 
than serpentine soils and are clay-like. In addition, the commenter 
stated the Service should obtain more detailed and accurate information 
regarding soil and vegetation before designating critical habitat.
    Our Response: The Service reviewed soil and geological data from 
multiple sources over multiple years, including geographic information 
system (GIS) data from Jones and Stokes (the primary consultant writing 
the Habitat Conservation Plan for Santa Clara County). All of the 
information the Service has obtained regarding soil type indicates that 
large tracks of serpentine or serpentine-like soils occur throughout 
the majority of the Metcalf Unit. The Service reevaluated the soil 
types present north of Metcalf Road, and based on our review of land 
ownership data and the most conservative soil maps, there are 
approximately 2,547 acres of serpentine soils in the area in question. 
While the analysis shows there are patches of nonserpentine soils 
present within the area, our data indicate that the vast majority of 
the site is comprised of soils from the Montara soil series. 
Additionally, the commenter did not provide the results of any surveys 
they may have conducted regarding soil types or vegetation that is 
currently found on their property, nor did they provide a map of their 
property.
    It is incumbent on the Service to use the best available 
information when making critical habitat determinations; however, the 
Service does not have adequate resources to undertake site-specific 
surveys throughout each critical habitat unit. If site-specific surveys 
are available that the Service was unaware of, the public comment 
period should be used to provide the Service with that information. In 
this case, the commenter noted that their own evaluation of the site 
indicated serpentine soils were not present over large portions of the 
site, but did not provide those evaluations (surveys) to the Service. 
Therefore, the area in Unit 4 referred to by the commenter has not been 
removed from this final designation of critical habitat.
    Comment 27: One commenter stated that the Service should not treat 
critical habitat designations as dispositive for consultations under 
the Act and that while conducting section 7 reviews, the Service should 
not use the critical habitat designation as conclusive.
    Our Response: The Service reviews the baseline information for each 
section 7 consultation. If site-specific habitat assessments have not 
been submitted with the initial consultation package, the Service 
typically requests an assessment be prepared. If a project is within a 
critical habitat designation, and the site assessment indicates the 
PCEs are not present within the action area or will not be adversely 
affected by the proposed action, then additional consultation with the 
Service is not required. The presence of the PCEs and the effects of 
the project on those PCEs determine whether formal consultation with 
respect to adverse modification or destruction of critical habitat is 
necessary.
    Comment 28: One commenter stated that according to their records 
they were not contacted regarding the proposed critical habitat 
designation, which included portions of their property. The commenter 
requested a 60-day extension on the comment period or reopening of the 
comment period due to lack of notification.
    Our Response: According to Service records, two attempts were made 
to contact the commenter by telephone and voice messages were left both 
times, but no response was received. In addition, the Service conducted

[[Page 50413]]

outreach by notifying appropriate elected officials, local 
jurisdictions, interested groups, and property owners. We conducted 
much of this outreach through legal notices in regional newspapers, 
telephone calls, letters, and news releases faxed or mailed to 
appropriate officials, local jurisdictions, and interest groups, and 
publication of the proposed determination and associated material on 
our Internet page. A second public comment period was opened for the 
draft economic analysis, and the Service contacted the commenter for a 
third time regarding the opportunity to provide comments. We believe we 
have provided sufficient time for public comment with two open comment 
periods totaling 90 days. Additionally, we are under a court-mandated 
due date to submit a final rule to the Federal Register by August 14, 
2008. In order to meet this date, we cannot open an additional comment 
period.
    Comment 29: The San Francisco Public Utilities Commission (SFPUC) 
stated they owned 203 ac (82.15 ha) within the Pulgas Ridge Unit (final 
Unit 1) and 130 ac (52.61 ha) within proposed the Edgewood Park Unit 
(final Unit 2).
    Our Response: According to the proposed and this final rule the 
Pulgas Ridge Unit is approximately 179 ac (72 ha) total in size, all of 
which is owned by the SFPUC. A review of GIS data indicates that more 
of the Edgewood Park Unit is owned by the SFPUC than stated in the 
proposed rule. According to our information the SFPUC owns 
approximately 140 ac (57 ha) within the Edgewood Park Unit. We have 
corrected the land ownership amount in this final rule.
    Comment 30: One commenter questioned whether the Pulgas Ridge Unit 
still supports all the PCEs.
    Our Response: It is not a requirement that each unit contain all 
the PCEs in order to be designated as critical habitat. However, a 
review of the vegetation data and soils and geology data indicate the 
unit has all the PCEs. In addition, site-specific information (i.e., 
surveys) was not provided by the commenter to support whether the unit 
contained all the PCEs or not, and two peer reviewers indicated that 
the unit is extensive and has topography similar to the Edgewood Park 
Unit, where Bay checkerspot butterflies were introduced in Spring 2007. 
The unit was occupied at the time of listing and contains all the 
features essential for the conservation of the subspecies; therefore, 
it meets the definition of critical habitat.
    Comment 31: One commenter stated they were in the early stages of 
preparing a Habitat Conservation Plan (HCP) for the Peninsula Watershed 
Management Plan, which includes portions of the Pulgas Ridge and 
Edgewood Park Units and that they are working to protect serpentine-
endemic species.
    Our Response: The Service supports actions taken by local 
governments and the general public to protect and enhance habitat for 
listed species through a variety of programs including Safe Harbor 
Agreements, Habitat Conservation Plans, our Partners for Fish and 
Wildlife Program, and other programs. The Service looks forward to 
working with the commenter in the preparation of an HCP in order to 
benefit serpentine species in the San Francisco Bay area.
    Comment 32: Two commenters stated that the purpose of designating 
critical habitat is to facilitate species recovery and that the Service 
should designate additional areas of unoccupied serpentine and 
nonserpentine habitat to ensure the recovery of the Bay checkerspot 
butterfly and sustain the metapopulation dynamics of the species.
    Our Response: In our revised proposed designation of critical 
habitat for the Bay checkerspot butterfly, we selected areas based on 
the best scientific data available that possess those physical and 
biological features essential to the conservation of the subspecies, 
and that may require special management considerations or protection. 
We included in the revised proposed designation areas that were 
occupied at the time of listing as well as one area occupied since the 
time of listing. However, the Service lacked specific information to 
indicate which, if any, unoccupied areas outside those we proposed are 
essential for the conservation of the species. The Service cannot 
designate as critical habitat areas occupied at the time of listing 
that we are unable to determine have the features essential to the 
conservation of the subspecies, or unoccupied areas that we are unable 
to determine are essential for the conservation of the species. 
Further, under section 3(5)(C) of the Act, critical habitat shall not 
include the entire geographical area that can be occupied by the 
species except in those circumstances determined by the Secretary of 
the Interior. Thus, in this rule, we only designate those areas we have 
determined meet the definition of critical habitat. The commenter did 
not provide information regarding unoccupied areas outside those we 
designated that would allow the Service to evaluate whether those areas 
supported the physical and biological features essential to the 
conservation of the subspecies. If such information becomes available 
in the future, the Service will consider proposing a revision to the 
critical habitat designation at that time or when our resources allow.
    Comment 33: Two commenters stated that PCE 1 should be modified. 
One commenter recommend PCE 1 be deleted and the other recommended a 
modification to remove the list of grass species.
    Our Response: All published literature on this species indicates it 
is a grassland species with relatively sedentary tendencies and may 
avoid areas of nonhabitat, including chaparral and oak woodland; 
therefore the Service believes the presence of grasslands is an 
essential component of Bay checkerspot butterfly habitat, although a 
list of specific grass species is not. In this final revised critical 
habitat rule, PCE 1 is ``The presence of annual or perennial grasslands 
with little to no overstory that provide north-south and east-west 
slopes with a tilt of more than 7 degrees for larval host plant 
survival during periods of atypical weather (for example, drought).'' 
We then list grassland species as examples of species common to 
grasslands in California, and since nonnative grasses are more common 
than native species, we include nonnative species in the example. The 
presence of any specific grass or grasses listed in the PCE is not 
required, and is not provided as a means to measure habitat quality, 
but merely as an indicator of grassland habitat; we clarify this in 
this final rule.
    Comment 34: Two commenters stated that the PCEs should include 
features that facilitate dispersal of the Bay checkerspot butterfly 
since dispersal between habitat patches is essential for 
recolonization, metapopulation persistence, and recovery. These 
commenters further stated that the Service did not designate sufficient 
critical habitat to allow for successful dispersal and that the Service 
should secure these areas and restore them.
    Our Response: PCE 1 includes both perennial and annual grasslands 
in order allow for dispersal. All of the units include some amount of 
nonserpentine grasslands interspersed with areas of serpentine and 
serpentine-like grasslands in order to enhance dispersal between the 
more suitable patches both within a unit and among units. In this way 
the Service has attempted to designate as many small patches within the 
boundaries of individual units, such as with the Metcalf and Kirby 
units, which support numerous populations and

[[Page 50414]]

subpopulations scattered over the entire eastern ridgeline in Santa 
Clara County. The Santa Teresa Hills Unit includes an area next to the 
Tulare Hill Unit that was specifically included in order to facilitate 
the dispersal of Bay checkerspot butterflies from the core population 
along Coyote Ridge on the eastern side of Santa Clara Valley, to the 
ridges on the western side of the valley. In addition, the Kalana Unit 
(Unit 9a and 9b) is also considered important for dispersing Bay 
checkerspot butterflies to the southernmost units (Units 10, 11, and 
12) in Santa Clara County. Based on the current occupancy of the 
majority of the units, the Service believes that dispersal between 
small populations within each unit, as well as between units, is 
occurring. For additional information please see the ``Criteria Used to 
Identify Critical Habitat'' section of this rule.
    Regarding the acquisition of land, the purchase and restoration of 
land for the benefit of the Bay checkerspot butterfly is beyond the 
scope of this rule.
    Comment 35: One commenter stated that PCE 5 (in the proposed rule 
and PCE 4 in this final rule) should include restored native grassland 
on nonserpentine soils and that researchers have suggested the Bay 
checkerspot butterfly's historic habitat included native grasslands on 
nonserpentine soils.
    Our Response: The Service agrees that some researchers have 
hypothesized that the range of the Bay checkerspot butterfly once 
included nonserpentine grasslands, which we noted in the proposed rule. 
The Service is not aware of any data that support the hypothesis. 
However, as noted in our response to comment 34, the Service included 
both perennial and annual grassland habitats as part of PCE 1. The 
presence of all PCEs was not a criterion used to designate critical 
habitat, and all units include areas of nonserpentine grasslands. In 
addition, the Service cannot predict where nonserpentine grassland 
habitats that will be restored in the future will be located, nor are 
we able to predict whether these areas would support other PCEs 
sufficient to support populations of the Bay checkerspot butterfly.
    Comment 36: One commenter stated that proposed PCE 6 (final rule 
PCE 5) should be revised to state that stable holes and cracks in the 
soil and surface rock outcrops, while beneficial and in need of 
protection, are not required for the habitat to have value.
    Our Response: The Service disagrees with the commenter regarding 
the importance of PCE 5 in this final rule. As stated in the proposed 
rule, White (1986, p. 58) observed that pupal mortality rates, as well 
as cause of mortality (i.e., predation, parasitism, crushing, or 
disease), varied significantly depending on location. For example, 
crushing was most likely in areas of bare ground, whereas pupae in 
areas with dense vegetation had a higher rate of mortality due to mold 
and viruses. Since pre-diapause larval mortality is the most 
significant factor influencing population size, a variety of diapause 
sites are necessary to ensure adequate numbers of larvae survive 
diapause. Further, because prescribed burns are an important management 
tool to control nonnative and invasive vegetation, diapause locations 
that are not at risk due to fire are important.
    Comment 37: One commenter stated that adopting PCEs 2 and 3 (larval 
host plants and adult nectar plants) risk causing temporary low-quality 
or degraded areas to be treated as non-habitat, which would allow their 
destruction or adverse modification.
    Our Response: Critical habitat designations are not required to 
support all PCEs over the ent