Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Bay Checkerspot Butterfly (Euphydryas editha bayensis), 48178-48218 [07-4060]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 72, Number 162 (Wednesday, August 22, 2007)]
[Proposed Rules]
[Pages 48178-48218]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 07-4060]



[[Page 48177]]

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Part III





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); 
Proposed Rule

Federal Register / Vol. 72, No. 162 / Wednesday, August 22, 2007 / 
Proposed Rules

[[Page 48178]]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

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: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
revise currently designated critical habitat for the bay checkerspot 
butterfly (Euphydryas editha bayensis) under the Endangered Species Act 
of 1973, as amended (Act). In total, approximately 19,746 acres (ac) 
(7,990 hectares (ha)) fall within the boundaries of the proposed 
revised critical habitat designation. The proposed revision to critical 
habitat is located in San Mateo and Santa Clara Counties, California.

DATES: We will accept comments from all interested parties until 
October 22, 2007. We must receive requests for public hearings, in 
writing, at the address shown in the ADDRESSES section by October 9, 
2007.

ADDRESSES: If you wish to comment on this proposed rule, you may submit 
your comments and materials concerning this proposal by any one of 
several methods:
    1. You may mail or hand-deliver written comments and information to 
Susan Moore, Field Supervisor, U.S. Fish and Wildlife Service, 
Sacramento Fish and Wildlife Office, 2800 Cottage Way, Room W-2605, 
Sacramento, CA 95825.
    2. You may send comments by electronic mail (e-mail) to bcb_
pch@fws.gov. Please see the Public Comments Solicited section below for 
file format and other information about electronic filing.
    3. You may fax your comments to the attention of Susan Moore, Field 
Supervisor at 916-414-6712.
    4. You may go to the Federal Rulemaking Portal: https://
www.regulations.gov. Follow the instructions for submitting comments.
    Comments and materials received, as well as supporting 
documentation used in the preparation of this proposed rule, will be 
available for public inspection, by appointment, during normal business 
hours at the Sacramento Fish and Wildlife Office, 2800 Cottage Way, 
Room 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. Persons who use a 
telecommunications device for the deaf (TDD) may call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

    We intend that any final action resulting from this proposal to 
revise the critical habitat designation for the bay checkerspot 
butterfly will be as accurate and as effective as possible. Therefore, 
we request comments or suggestions from the public, other concerned 
governmental agencies, the scientific community, industry, or any other 
interested party on this proposed rule. We particularly seek comments 
concerning:
    (1) The reasons why we should or should not designate habitat as 
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et 
seq.), including whether there are areas we previously designated, but 
are not proposing for revised designation here, that should be 
designated as critical habitat.
    (2) Specific information on the amount and distribution of bay 
checkerspot butterfly habitat.
    (3) Specific information whether the features we have proposed as 
essential for the conservation of the species (Primary Constituent 
Elements) are adequate, and if not, what alternatives should be 
considered (see also item (13)).
    (4) The reason why any areas that were occupied at the time of 
listing and that contain the features that are essential for the 
conservation of the species should or should not be included in the 
designation.
    (5) The reason why any areas that were not occupied at the listing 
may be essential to the conservation of the species, and why such areas 
should or should not be designated as critical habitat.
    (6) Specific information on dispersal areas important for habitat 
connectivity, in particular areas between Units 1 and 2 and between 
Unit 4 and the Santa Clara County Units, their role in the conservation 
and recovery of the species, and reasons why such areas should or 
should not be included in the critical habitat designation.
    (7) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed revised critical 
habitat.
    (8) Any foreseeable economic, national security, or other potential 
impacts resulting from the proposed designation and, in particular, any 
impacts on small entities.
    (9) Whether our approach to designating critical habitat could be 
improved or modified in any way to provide for greater public 
participation and understanding, or to assist us in accommodating 
public concerns and comments.
    (10) Specific comments regarding occupancy and habitat quality of 
the proposed Pulgas Ridge Unit 2.
    (11) The relative benefits of designation or exclusion of any lands 
from proposed revised critical habitat such as Habitat Conservation 
Plans (HCPs), Safe Harbor Agreements (SHA), or other areas that have 
management plans in place that provide for bay checkerspot butterfly 
conservation. We especially seek specific comments regarding the 
potential exclusion of areas within the final San Bruno Mountain HCP 
(proposed Unit 1), and areas within the planned Stanford HCP (proposed 
Unit 4), and the Santa Clara County HCP (proposed Units 5-12).
    (12) Specific comments regarding population sizes of the bay 
checkerspot butterfly within those areas proposed for designation as 
revised critical habitat.
    (13) Specific documentation regarding the use of water sources by 
the bay checkerspot butterfly, particularly to support or refute our 
proposed primary constituent element of water features (Primary 
Constituent Element 4), and whether water sources are essential for the 
conservation of the subspecies.
    You may submit your comments and materials concerning this proposal 
by any one of several methods (see ADDRESSES). If you use e-mail to 
submit your comments, please include ``Attn: [species]'' in your e-mail 
subject header, preferably with, your name and return address in the 
body of your message. If you do not receive a confirmation from the 
system that we have received your e-mail, contact us directly by 
calling our Sacramento Fish and Wildlife Office at 916-414-6600. Please 
note that we must receive comments by the date specified in the DATES 
section in order to consider them in our final determination and that 
the e-mail address bcb_pch@fws.gov will be closed out at the 
termination of the public comment period.
    Before including your address, phone number, e-mail address, or 
other personal identifying information in your comment, you should be 
aware that your entire comment--including your personal identifying 
information--may be made publicly available at any time. While you may 
ask us to withhold your personal identifying information from

[[Page 48179]]

public review, we cannot guarantee that we will be able to do so.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection, by appointment, during normal business 
hours at the Sacramento Fish and Wildlife Office, 2800 Cottage Way, 
Room W-2605, Sacramento, CA 95825 (telephone 916-414-6600).

Background

    It is our intent to discuss only those topics directly relevant to 
the designation of critical habitat in this proposed rule. For more 
information on the bay checkerspot butterfly, refer to the listing rule 
and previous determination of critical habitat published in the Federal 
Register on September 18, 1987 (52 FR 35366) and April 30, 2001 (66 FR 
21450), respectively.
    The September 18, 1987, final listing rule (52 FR 35366) described 
the bay checkerspot butterfly as occupying seven areas in San Mateo and 
Santa Clara counties: (1) San Bruno Mountain; (2) Pulgas Ridge; (3) 
Edgewood Park; (4) Jasper Ridge; (5) Coyote Ridge (referred to in the 
listing rule as a portion of the east face of Coyote Creek Valley 
between Metcalf Road and the Anderson Lake outlet); (6) Calero 
Reservoir; and (7) San Martin. Subsequent to listing, five additional 
populations were identified: (1) Tulare Hill; (2) Santa Teresa Hills; 
(3) Kalana Hills; (4) Morgan Hill; and (5) Bear Ranch. Of these 
additional populations, four will be considered occupied at the time of 
listing because they were known from published literature at the time 
of listing, but they were not specifically mentioned in the listing 
rule. The fifth population (Bear Ranch) was mentioned in the listing 
rule as extirpated; however, in 1994 thousands of bay checkerspot 
butterflies were observed at this location (CNDDB 2006 p. 15). In 
addition to the locations known at the time of listing, the subspecies 
was historically known from near Berkeley, California; at Joaquin 
Miller Park in Alameda County; in San Francisco County from Twin Peaks 
and Mount Davidson; and in Contra Costa County near Morgan Territory 
Road (Murphy and Ehrlich 1980, p. 318). However, these populations 
disappeared as a result of a variety of factors including highway and 
subdivision construction, drought, overgrazing, and invasion of 
nonnative plants (Murphy and Ehrlich 1980, p. 319).

Distribution and Population Trends

    The population size of the bay checkerspot butterfly is primarily 
determined by the survival rate of prediapause larvae (Singer 1972, p. 
77; Weiss et al. 1988, p. 1486). Prediapause larva experience mortality 
rates upwards of 95 percent (Murphy 1988, p. 46; Weiss et al. 1988, p. 
1487; Cushman et al. 1994, p. 198; Murphy et al. 2004, p. 26). Larval 
survivorship is dependent upon the timing of host plant senescence, 
which in turn is dependent on environmental conditions such as 
rainfall. Rainfall in the San Francisco Bay area is known to vary 
dramatically (Weiss et al. 1988, p. 1495). The further a particular 
location is from another, the greater the likelihood each will receive 
dramatically different rainfall, so plants in areas that experience the 
same environmental conditions (i.e., those in close proximity and on 
similar topography) would result in larvae in those locations likely 
experiencing the same fate.
    Since listing in 1987, the distribution and population size of the 
bay checkerspot butterfly has changed substantially. In San Mateo 
County, the subspecies' population numbers have declined dramatically. 
The populations at San Bruno Mountain, Pulgas Ridge, and Jasper Ridge 
have not been detected in limited surveys, and reintroduction efforts 
were initiated at Edgewood Park to ensure the San Mateo County 
populations remain viable. Approximately 1,000 postdiapause larvae were 
reintroduced to Edgewood Park in February and March 2007. Prior to 
reintroductions between February and March 2007, the bay checkerspot 
butterfly had not been observed at Edgewood Park since 2002 (CNDDB 
2006). Limited surveys on a small southeastern portion of Pulgas Ridge, 
dated 1989-1993 and 1994, failed to detect any individual bay 
checkerspot butterflies (CNDDB 2007). However, these surveys covered 
only a small portion of the available habitat that was historically 
occupied.
    In Santa Clara County, population trends for the bay checkerspot 
butterfly are only available for portions of Coyote Ridge (identified 
as units 8, 10, 11, and 12 in the 2001 designation (66 FR 21450)), 
Tulare Hill, and Bear Ranch. On Coyote Ridge, south of Metcalf Road 
(2001 unit 8) bay checkerspot butterfly numbers increased from 
approximately 20,000 individuals in 1997 to 700,000 individuals in 
2004, but fell to approximately 100,000 individuals in 2005 (Weiss 
2006, p. 1). On Coyote Ridge, north of Metcalf Road (2001 unit 10), bay 
checkerspot butterfly numbers increased from approximately 200,000 in 
2000 to 400,000 in 2004, but then declined to 45,000 in 2006 (Weiss 
2006, p. 1).
    Larval estimates from Silver Creek Hills (2001 unit 12), also on 
Coyote Ridge, increased from 75,000 in 1992 to 128,000 in 1993, but 
then fell to an estimated 58,000 in 1994 following the removal of 
grazing from portions of the area (Weiss 1996, p. 93; Weiss 1999, p. 
1480), and no larvae or adults were observed in 1998 (Weiss 1999, p. 
1480). Annual surveys at Silver Creek Hills since the construction of a 
residential subdivision and reintroduction of grazing over portions of 
the area in 2000-2001, showed a slight increase from a low of 11 adults 
in 2001 to 51 in 2005 (WRA 2006, p. 10). Forty adult bay checkerspot 
butterflies were observed in the Silver Creek Hills area in 2006, but 
no larvae were observed (WRA 2006, p. 10).
    Post-diapause larvae on Tulare Hill (2001 unit 15) numbered 
approximately 2,000 individuals in 2002; the population declined 
significantly in 2003, with only 1 post-diapause larvae observed (CH2M 
Hill 2004, p. 8-6). Five adult bay checkerspot butterflies were 
observed on Tulare Hill in 2004 (CH2M Hill 2005, p. 8-2). According to 
Weiss (2007, p. 1), based on the number of individuals observed on 
Tulare Hill in 2004, the population size was estimated at approximately 
100 individuals. Seven adult bay checkerspot butterflies were observed 
on Tulare Hill in 2005; however, no post-diapause larvae were observed 
(CH2M Hill 2006, p. 8-2).
    According to California Natural Diversity Database CNDDB (2006) 
records, thousands of adult bay checkerspot butterflies were observed 
at Bear Ranch in 1994, 6 adults were observed in 1997, and 1 adult was 
observed in 1999. The Service is unaware of any other surveys regarding 
the status of the subspecies within this unit.

Population Dynamics

    Studies of the bay checkerspot butterfly's population dynamics 
characterize it as having a metapopulation dynamic. These studies were 
influential in the formulation of the metapopulation concept (Ehrlich 
et al. 1975, pp. 221-228; Harrison 1994, pp. 111-128). A metapopulation 
is a group of spatially distinct populations that can occasionally 
exchange dispersing individuals. The populations in a metapopulation 
are usually thought of as having interdependent extinction and 
colonization processes, where individual populations may be extirpated 
from a local area and later be

[[Page 48180]]

recolonized from another population that is still extant. The frequency 
of local extirpation and time until recolonization vary widely from 
population to population, depending on numerous demographic and 
environmental factors, such as the size and quality of the habitat, 
distance from other populations, size of other populations, mobility of 
the species, and weather. At the time of listing, two metapopulations 
were known to occur; one in San Mateo County and the other in Santa 
Clara County.
    The current bay checkerspot butterfly range is much reduced, and 
the butterfly is patchily distributed. Because it occurs as a 
metapopulation, the exact distribution of the butterfly varies through 
time: Sites that are unoccupied one year may be occupied the next, and 
vice versa (Wilcox and Murphy 1985, p. 882; Harrison 1994, p. 114).

Previous Federal Actions

    For information on previous Federal actions concerning the bay 
checkerspot butterfly, refer to the final listing rule published in the 
Federal Register on September 18, 1987 (52 FR 35366), and the 
designation of critical habitat published in the Federal Register on 
April 30, 2001 (66 FR 21450). On September 30, 1998, we published a 
recovery plan for Serpentine Soil Species of the San Francisco Bay Area 
that included the bay checkerspot butterfly. On April 30, 2001, we 
designated critical habitat on approximately 23,903 acres (9,673 
hectares) of land 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 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 other 
applicable law. As a result, we propose revisions to the rule. The 
settlement stipulated that any proposed revisions to the bay 
checkerspot butterfly designation be submitted to the Federal Register 
for publication on or before August 14, 2007.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as: (i) The 
specific areas within the geographical area occupied by a species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographical area occupied by a species at the time it is listed, upon 
a determination that such areas are essential for the conservation of 
the species.
    Conservation, as defined under section 3 of the Act, means the use 
of all methods and procedures that are necessary to bring any 
endangered species or threatened species to the point at which the 
measures provided under the Act are no longer necessary.
    Critical habitat receives protection under section 7 of the Act 
through the prohibition against Federal agencies carrying out, funding, 
or authorizing the destruction or adverse modification of critical 
habitat. Section 7 of the Act requires consultation on Federal actions 
that may affect critical habitat. The designation of critical habitat 
does not affect land ownership or establish a refuge, wilderness, 
reserve, preserve, or other conservation area. Such designation does 
not allow government or public access to private lands. Section 7 of 
the Act is a purely protective measure and does not require 
implementation of restoration, recovery, or enhancement measures.
    For inclusion in a critical habitat designation, habitat within the 
geographical area occupied by the species at time of listing must first 
have features that are essential to the conservation of the species. 
Critical habitat designations identify, to the extent known using the 
best scientific data available, habitat areas that provide essential 
life cycle needs of the species (areas on which are found the primary 
constituent elements, as defined at 50 CFR 424.12(b)).
    Occupied habitat that contains the features essential to the 
conservation of the species meets the definition of critical habitat 
only if its essential features may require special management 
considerations or protection.
    We can designate unoccupied areas as critical habitat. However, 
when the best available scientific data do not demonstrate that the 
conservation needs of the species require additional areas, we will not 
designate critical habitat in areas outside the geographical area 
occupied by the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific and commercial data available. 
Further, our Policy on Information Standards Under the Endangered 
Species Act (published in the Federal Register on July 1, 1994 (59 FR 
34271)), the Information Quality Act (section 515 of the Treasury and 
General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 
106-554; H.R. 5658) and our associated Information Quality Guidelines, 
provide criteria, establish procedures, and provide guidance to ensure 
that our designation represent the best scientific data available. They 
require our biologists, to the extent consistent with the Act and with 
the use of the best scientific data available, to use primary and 
original sources of information as the basis for recommendations to 
designate critical habitat. When we are determining which areas to 
propose as critical habitat, our primary source of information is 
generally the listing package for the species. Additional information 
sources may include the recovery plan for the species, articles in 
peer-reviewed journals, conservation plans developed by States and 
counties, scientific status surveys and studies, biological 
assessments, or other unpublished materials and expert opinion or 
personal knowledge.
    Habitat is often dynamic, and species may move from one area to 
another over time. Furthermore, we recognize that designation of 
critical habitat may not include all habitat areas that we may 
eventually determine are necessary for the recovery of the species. For 
these reasons, a critical habitat designation does not signal that 
habitat outside the designated area is unimportant or may not be 
required for recovery.
    Areas that support populations of the bay checkerspot butterfly, 
but are outside the critical habitat designation, will continue to be 
subject to conservation actions we implement under section 7(a)(1) of 
the Act. They are also subject to the regulatory protections afforded 
by the section 7(a)(2) jeopardy standard, as determined on the basis of 
the best available information at the time of the agency action. 
Federally funded or permitted projects affecting listed species outside 
their designated critical habitat areas may still result in jeopardy 
findings in some cases. Similarly, critical habitat designations made 
on the basis of the best available information at the time of 
designation will not control the direction and substance of future 
recovery plans, habitat conservation

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plans (HCPs), or other species conservation planning efforts if new 
information available to these planning efforts calls for a different 
outcome.

Methods

    As required by section 4(b) of the Act, we used the best scientific 
data available in determining areas that contain the features essential 
to the conservation of the bay checkerspot butterfly, and areas 
unoccupied at the time of listing that are essential to the 
conservation of the bay checkerspot butterfly or both. This includes 
information used to prepare the 2001 designation of critical habitat 
(66 FR 21450), the Recovery Plan for Serpentine Soil Species of the San 
Francisco Bay Area, the CNDDB, published and unpublished papers, 
reports, academic theses and surveys, Geographic Information System 
(GIS) data (such as species occurrence, soil data, land use, 
topography, and ownership maps), correspondence to the Service from 
recognized experts, and other information as available.
    We have also reviewed available information that pertains to the 
habitat requirements of this species including:
     Data in reports submitted during section 7 consultations 
and submitted by biologists holding section 10(a)(1)(A) recovery 
permits;
     Research published in peer-reviewed articles and presented 
in academic theses and agency reports;
     Information from species experts; and
     Information gathered during site visits to bay checkerspot 
butterfly habitat in Santa Clara County.

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12, in determining which areas to propose as revised 
critical habitat within areas occupied by the species at the time of 
listing, we consider the primary constituent elements (PCEs) to be 
those physical and biological features that are essential to the 
conservation of the species and that may require special management 
considerations and protection. These include, but are not limited to, 
space for individual and population growth and for normal behavior; 
food, water, air, light, minerals, or other nutritional or 
physiological requirements; cover or shelter; sites for breeding, 
reproduction, and rearing (or development) of offspring; and habitats 
that are protected from disturbance or are representative of the 
historic geographical and ecological distributions of a species.
    The specific PCEs required for the bay checkerspot butterfly are 
derived from the biological needs of the bay checkerspot butterfly as 
described in the Background sections of this proposal and in the final 
listing rule published in the Federal Register on September 18, 1987 
(52 FR 35366).

Space for Individual and Population Growth and for Normal Behavior

    The bay checkerspot butterfly occurs in open grassland habitats of 
the San Francisco Bay in Santa Clara and San Mateo counties. Prior to 
European settlement, California grasslands are believed to have been 
comprised of perennial bunchgrasses with both annual and perennial 
forbs (Jackson 1985, p. 349; Huenneke et al. 1990, p. 478; Corbin and 
D'Antonio 2004, p. 1273). Today, grassland habitats in California are 
almost entirely composed of Eurasian annual grasses and forbs (Jackson 
1985, p. 349; Huenneke et al. 1990, p. 478; Seabloom et al. 2003, p. 
13384; Malmstrom et al. 2005, p. 154) where classical succession does 
not occur (Huenneke et al. 1990, p. 478; Kie 2005, p. 2). Plant density 
in nonnative grasslands is extremely high compared to plant density in 
native grasslands (Malmstrom et al. 2005, p. 154). Dyer and Rice (1997, 
pp. 484, 490) estimated that pre-settlement densities of some native 
species was between 1-7 mature individuals per square meter. This is in 
sharp contrast to densities of several nonnative grasses and forbs; a 
study by Biswell and Graham (1958, p. 116-117) found densities of some 
nonnative species, such as Bromus hordeaceus, Erodium botrys, and 
Festuca megalura, to be 20,000 to 78,000 mature individuals per square 
meter. Heady (1958, p. 405) observed somewhat lower densities than 
Biswell and Graham (1958) of the same species with densities ranging 
from 4,750 to 28,370 mature individuals per square meter. This suggests 
that grasslands with nonnative species have large numbers of 
individuals, but few species (i.e., low diversity). According to 
Malmstrom et al. (2005, p. 154), California native grasslands, prior to 
the introduction of Eurasian vegetation, were likely a mix of forbs and 
grasses, but today these species are out-competed by nonnative grasses.
    Serpentine or serpentine-like soils are characterized as shallow, 
nutrient poor (typically lacking in nitrogen and calcium), containing 
high magnesium (and other heavy metals), and with low water holding 
capacity. All currently occupied habitats of the bay checkerspot 
butterfly occur on serpentine or serpentine-like grasslands that 
support at least two of the subspecies' larval host plants. Due to poor 
nutrient availability, as well as other soil characteristics, 
serpentine and serpentine-like grasslands are, for the most part, 
inhospitable to the nonnative grasses and forbs that dominate other 
California grassland ecosystems; these areas are essentially isolated 
patches where native grassland vegetation is capable of persisting in a 
landscape, otherwise dominated by nonnative and invasive species. These 
soils support many rare plant species including populations of the bay 
checkerspot butterfly's larval host plants Plantago erecta, Castilleja 
densiflora, and Castilleja exserta. However, these remnant native 
grasslands are being invaded and crowded out by nonnative species and 
are under increased pressure as a result of nitrogen deposition 
primarily caused by air pollution (Weiss 1999, p. 1477). The enrichment 
of these soils with nitrogen has allowed nonnative grasses to invade 
these traditionally nutrient poor habitats, and the result is a thick 
mat of standing vegetation (thatch). Dense thatch has been reported to 
inhibit the growth of native forbs (Huenneke et al. 1990, p. 488). 
Huenneke et al. (1990, p. 489) found that treatment areas that were 
fenced to prevent grazing resulted in an increase in native perennial 
and nonnative annual grasses, but in grazed treatments forbs continued 
to represent an important component. Low and moderate grazing regimes, 
approximately one cow per 10 acres, have been implemented on portions 
of Tulare Hill and Coyote Ridge. Because cattle tend to select 
nonnative grasses over native forbs (Weiss 1999, p. 1484), the result 
of these grazing regimes has been local increases of the bay 
checkerspot butterfly's larval host plants.
    The bay checkerspot butterfly requires areas with topographic 
diversity (warm south and west slopes as well as cool north and east 
slopes), because some slopes become unfavorable depending on annual 
weather conditions and time of year. Fleishman et al. (2000, p. 34) 
defined warm and very warm slopes as south- and west-facing slopes with 
a tilt greater than 11 and 17 degrees, respectively, with cool and very 
cool slopes defined as those facing north or east with a tilt greater 
than 11 and 17 degrees, respectively. Harrison et al. (1988, p. 365) 
defined warm slopes as those facing south, southwest, and southeast 
with a tilt greater than 7 degrees and cool slopes as those facing 
north or northeast with a tilt greater than 7 and 12 degrees, 
respectively. In

[[Page 48182]]

hot, dry years, north- and east-facing slopes remain cool and moist 
longer and larval host plants tend to senesce (reach later maturity; 
grow old) later than those on other slopes (Weiss et al. 1988, p. 1493; 
Fleishman et al. 2000, p. 33). The delayed senescence of plants on 
cool/moist slopes allows larvae to reach their fourth instar (larval 
development stage/molt) and enter diapause (dormancy) before host 
plants become inedible. Larvae that are not able to enter diapause 
prior to host plant senescence starve and die (Singer and Ehrlich 1979, 
p. 54; White 1987, p. 209; Weiss 1996, p. 6). Because host plants on 
cool slopes can flower and senesce three or more weeks after those on 
warmer slopes (Weiss et al. 1988, p. 1493), cool slopes are especially 
important during extremely dry years (i.e., droughts). However, larval 
feeding and growth tends to increase on warm slopes because they 
receive more solar exposure than other slopes; this allows post-
diapause larvae to grow quickly and pupate earlier than those on cool 
slopes. Individuals that pupate earlier have a much greater chance of 
reproductive success (Weiss et al. 1988, pp. 1493-94).
    In addition to weather, slope is important relative to the timing 
of egg laying. As the adult mating season (referred to as the flight 
season) progresses, females tend to lay more eggs on cool slopes than 
on warm slopes (Weiss et al. 1988, p. 1493). The timing of the adult 
flight season varies with weather, but can generally be described as 
occurring from late February to early May (Murphy et al. 2004, p. 25). 
Larvae that hatch late in the flight season have a greater chance of 
reaching diapause on cooler slopes than those laid at the same time on 
warm slopes, because host plants mature later on cool slopes. The 
pattern of larval survivorship across different slopes changes from one 
year to the next as well as within years; therefore, it becomes 
important that a variety of slopes and aspects are present to support 
the butterfly and its host plants.

Food

    The primary larval host plant for the bay checkerspot butterfly is 
a small, annual, native plantain (Plantago erecta). The bay checkerspot 
butterfly also requires the presence of a secondary host plant, either 
purple owl's-clover (Castilleja densiflora) or exserted paintbrush 
(Castilleja exserta) (Singer 1972, p. 76; Murphy and Ehrlick 1980, p. 
316; Fleishman et al. 1997, p. 32; Weiss 1999, p. 1478; Hellman 2002, 
pp. 926, 931). The need for a secondary host plant is related to the 
timing of senescence of the primary host plant. In many years, the 
primary host plant dries up before larvae have reached their fourth 
instar and entered diapause. Because purple owl's-clover and exserted 
paintbrush tend to senesce later than the plantain, larvae that switch 
to these plants may extend their feeding season long enough to reach 
their fourth instar.
    Adult bay checkerspot butterflies utilize nectar from a variety of 
plants associated with serpentine grasslands. Commonly used nectar 
plants include desert parsley (Lomatium spp.), California goldfields 
(Lasthenia californica), tidy-tips (Layia platyglossa), sea muilla 
(Muilla maritima), scytheleaf onion (Allium falcifolium), false 
babystars (Linanthus androsaceus), and intermediate fiddleneck 
(Amsinckia intermedia). Egg production (both size of individual eggs 
and number of eggs) significantly increases with the intake of 
nutrients (Murphy et al. 1983, p. 261; Boggs 1997a, pp. 181, 184). 
Murphy et al. (1983, p. 261) observed increased longevity and reduced 
weight loss in adult bay checkerspot butterflies that were fed sugar. 
Murphy et al. (1983, p. 261) also observed that amino acid intake 
produced heavier eggs and that larvae from these eggs had an increased 
likelihood of survival. A study by O'Brien et al. (2004, p. 286), which 
examined egg production and adult diet in three species of butterflies 
in the family Nymphalidae, found the percent of carbon in eggs, derived 
from adult diets, increased with time (up to 80 percent in one 
species). Currently there is no information regarding nectar usage on 
adult male longevity or reproduction.
    All of the host plants have ranges greater than that of the bay 
checkerspot butterfly and the larval plants may be found in areas that 
do not meet the life-history requirements of the bay checkerspot 
butterfly. For example, Castilleja densiflora historically occurred 
throughout California, Plantago erecta occurred throughout California 
and Oregon, and Castilleja exserta occurred in California, Arizona, New 
Mexico, Hawaii, and Massachusetts (USDA 2007). In addition, the range 
of many of the nectar sources is also much greater than the geographic 
range of the bay checkerspot butterfly.

Water

    Launer et al. (1993, p. 45) observed large numbers (hundreds) of 
checkerspots, predominately females, ``puddling'' at a creek in 1990. 
Puddling is a behavior observed in some butterfly species in which 
adults take up moisture from saturated soils. Launer et al. (1993, pp. 
48-50) provided several alternative hypotheses for explaining the 
observed puddling behavior, since the bay checkerspot butterfly was not 
traditionally believed to be a puddling species. One hypothesis was 
that because the observation was made during an extremely dry period 
(third year of a drought), the creek was providing resources that were 
otherwise unavailable (or only in low quantities), and that moist areas 
may provide an increased chance of survival during drought periods 
(Launer et al. 1993, p. 49). Murphy et al. (1983, p. 261) observed that 
under laboratory conditions female bay checkerspot butterflies lived 
longer when provided water. Checkerspots are not generally considered 
puddling butterflies, and some researchers consider it very unusual for 
members of the genus Euphydryas to exhibit puddling behavior (Emmel 
2007, p. 1). However, the observation of large numbers of bay 
checkerspot butterflies taking water from the banks of a creek provides 
evidence for a need for aquatic features (i.e., water).

Soils

    The bay checkerspot butterfly inhabits areas with soils derived 
from serpentinite ultramafic rock (Montara, Climara, Henneke, Hentine, 
and Obispo soil series) or similar non-serpentine soils (such as Inks, 
Candlestick, Los Gatos, Fagan, and Barnabe soil series). Serpentine 
soils are characterized as having low amounts of nutrients (such as 
nitrogen and calcium); high concentrations of magnesium; low water-
holding capacity; and patches of heavy metals. These characteristics 
create a refuge for many rare native plants, because other plant 
species are not capable of surviving in these soils (nitrogen is often 
a limiting factor in plant growth). The nonserpentine soils mentioned 
above have characteristics that allow them to support grassland 
communities similar to those on serpentine soils, such as low water-
holding capacity, slight to moderate acidity (pH 5.8), and varied 
topography (slopes ranging from 5 to 75 percent). Together, these soils 
provide the last remaining habitat within the geographic range of the 
bay checkerspot butterfly where the larval host plants are capable of 
persisting and not be outcompeted or crowded out by introduced annuals. 
Some researchers have hypothesized that the bay checkerspot butterfly 
once occurred widely in nonserpentine grasslands throughout the San 
Francisco Bay area prior to the invasion of nonnative invasive grasses 
and forbs

[[Page 48183]]

(Murphy and Weiss 1988, p. 197), but have subsequently been relegated 
to these fragmented habitats due to plant competition.

Cover

    Larval bay checkerspot butterflies enter diapause in order to 
survive the summer dry period, once their host plants senesce. Diapause 
is an obligatory dormancy period that begins once larvae reach their 
fourth instar, which takes approximately three weeks, but may vary 
considerably depending on abiotic factors (non-living components of the 
biosphere) (Kuussaari, et al. 2004, p. 140). Evidence suggests that 
larvae may be capable of entering diapause more than once (White and 
Levin 1981, p. 355; Harrison 1989, p. 1242; Kuussaari et al. 2004, pp. 
139-140; Mattoni et al. 1997, p. 106). Diapause continues until the 
summer dry period is broken by the onset of the rainy season, generally 
some time in November-January (Weiss 1996, p. 6). The larvae pass 
through diapause in holes and cracks in the soil and under rocks (White 
1987, p. 209; Weiss 1996, p. 7) that provide protection from weather, 
predation, and parasitism. 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, with significant differences in mortality between 
microhabitat types. 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.

Primary Constituent Elements for the Bay Checkerspot Butterfly

    Within the geographical area we know to be occupied by the bay 
checkerspot butterfly, we must identify the PCEs that may require 
special management considerations or protections.
    Based on the above needs and our current knowledge of the life 
history, biology, and ecology of the species, we have determined that 
bay checkerspot butterfly PCEs are:
    (1) 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 (e.g., drought). Common grassland species include wild 
oats (Avena fatua), soft chess (Bromus hordeaceus), California oatgrass 
(Danthonia californica), purple needlegrass (Nassella pulchra), and 
Idaho fescue (Festuca idahoensis); less abundant in these grasslands 
are annual and perennial forbs such as filaree (Erodium botrys), true 
clovers (Trifolium sp.), dwarf plantain (Plantago erecta), and turkey 
mullein (Croton setigerus).
    (2) The presence of the primary larval host plant, dwarf plantain 
(Plantago erecta) and at least one of the secondary host plants, purple 
owl's-clover (Castilleja densiflora) or exserted paintbrush (Castilleja 
exserta), are required for reproduction, feeding, and larval 
development.
    (3) The presence of adult nectar sources for feeding. Common nectar 
sources include desertparsley (Lomatium spp.), California goldfields 
(Lasthenia californica), tidy-tips (Layia platyglossa), sea muilla 
(Muilla maritima), scytheleaf onion (Allium falcifolium), false 
babystars (Linanthus androsaceus), and intermediate fiddleneck 
(Amsinckia intermedia).
    (4) Aquatic features such as wetlands, springs, seeps, streams, 
lakes, and ponds and their associated banks, that provide moisture 
during periods of spring drought; these features can be ephemeral, 
seasonal, or permanent.
    (5) Soils derived from serpentinite ultramafic rock (Montara, 
Climara, Henneke, Hentine, and Obispo soil series) or similar soils 
(Inks, Candlestick, Los Gatos, Fagan, and Barnabe soil series) that 
provide areas with fewer aggressive, nonnative plant species for larval 
host plant and adult nectar plant survival and reproduction.
    (6) The presence of stable holes and cracks in the soil, and 
surface rock outcrops that provide shelter for the larval stage of the 
bay checkerspot butterfly during summer diapause.
    We have designed this proposed revision to the critical habitat 
designation for the conservation of PCEs necessary to support the life-
history functions that were the basis for our proposal and the areas 
containing those PCEs. Because not all life-history functions require 
all the PCEs, not all proposed critical habitat will contain all the 
PCEs.
    We propose units for designation based on sufficient PCEs being 
present to support one or more of the species' life-history functions. 
Some units contain all PCEs and support multiple life processes, while 
some units contain only a portion of the PCEs necessary to support the 
species' particular use of that habitat.

Special Management Considerations or Protections

    When designating critical habitat, we assess whether the areas 
determined to be occupied at the time of listing and contain the 
primary constituent elements may require special management 
considerations or protections. Threats to those features that define 
the PCEs for the bay checkerspot butterfly include habitat loss and 
fragmentation, invasion of exotic/invasive plants, nitrogen deposition 
(including NOX and ammonia), pesticide application 
(including drift), illegal collecting, fire, overgrazing, and gopher 
control.
    Critical habitat units 1, 2, and 5-10 may require special 
management due to threats posed by habitat loss and fragmentation 
resulting from urban and suburban growth. Development pressure in Santa 
Clara County is likely to increase in the foreseeable future. The City 
of San Jose has developed a General Plan to guide development in the 
area into the year 2020 and is not part of the proposed Santa Clara 
County HCP. Portions of the general plan share boundaries with critical 
habitat units, including Units 5, 6, 7, and 9. Some currently or 
proposed projects include the Coyote Valley Specific Plan, which 
includes residential and industrial developments, the Coyote Valley 
Research Park, numerous projects currently proposed for inclusion under 
the Santa Clara Habitat Conservation Plan, as well as numerous single 
family residential units and road grading projects. In 1997, the 
California Court of Appeals 6th District found that the City of San 
Jose's zoning did not have to be consistent with the City's General 
Plan (Juarez et al. v. City of San Jose et al. (6th District, Case No. 
CV736436 H014755)); this may result in areas not currently within the 
urban growth boundary still being proposed for development, including 
those areas that are environmentally sensitive such as critical habitat 
units. In addition, portions of Unit 10 are within the planning 
boundaries of the City of Morgan Hill's General Plan.
    All proposed revised critical habitat units would likely require 
special management due to the threats posed by the invasion of 
nonnative vegetation that result from air pollution (primarily nitrogen 
deposition) (Weiss 1999, p. 1477). Nitrogen deposition enriches 
serpentine and serpentinelike soils that are usually nutrient poor. 
Increased nitrogen (typically a limiting factor in plant growth) in 
these areas has resulted in the accumulation of a thick carpet of 
vegetative material (thatch) each year. Dense thatch has been reported 
to inhibit the growth of native forbs (Huenneke et al. 1990, p. 488). 
The increased density of nonnative vegetation would negatively affect 
the bay checkerspot butterfly's host plant through competition and 
crowding (Weiss 1999, p. 1481).

[[Page 48184]]

    All proposed revised critical habitat units may require special 
management due to the threats posed by pesticide use. Use of pesticides 
(i.e., insecticides, and herbicides) in or adjacent to critical habitat 
may affect populations of butterflies within these units. Populations 
adjacent to areas where there is intensive use of pesticides may be at 
risk as a result of drift and runoff. In at least one instance, larvae 
appeared to have survived a direct application of malathion by the 
California Department of Food and Agriculture; however, the application 
was conducted in the fall of 1981 when larvae were still in diapause.
    All proposed revised critical habitat units may require special 
management due to the threat posed by fire. No bay checkerspot 
butterflies were seen on San Bruno Mountain after a wildfire swept 
across portions of the mountain in 1986. However, only about 50 adult 
butterflies were observed on the mountain in 1984 (CNDDB 2006), so 
their subsequent disappearance may not have been solely related to the 
1986 fire. The use of fire as a management regime in serpentine 
grasslands has not been well studied. Studies that have been conducted 
are primarily monitoring opportunities made possible after wildfires.
    Use of prescribed burns may be an effective management tool 
depending on timing, intensity, and size of the area burned. Prescribed 
burns are widely used as a land management tool to counter the invasion 
of nonnative and invasive plant species and to stimulate growth and 
reproduction of those species adapted to disturbance. An experimental 
prescribed burn was conducted over a small portion of Coyote Ridge in 
2006, but the results are not yet known.
    All proposed revised critical habitat units may require special 
management due to the threat posed by over or under grazing. Although 
grazing is frequently used as a management tool to reduce standing 
biomass of nonnative vegetation, overgrazing can be a potential threat 
if grazing densities are not appropriately managed. Huenneke et al. 
(1990, p. 489) and Weiss (1999, p. 1480) found that areas that were 
fenced to prevent grazing or sites where grazing had been removed, 
resulted in an increase in annual grasses, which crowd out forbs 
including those that are essential to the bay checkerspot butterfly. 
Forbs continued to be an important component in areas that included 
limited grazing. Therefore, we consider a limited amount of grazing to 
be beneficial to bay checkerspot habitat.
    All proposed revised critical habitat units may require special 
management due to the threats posed by gopher control. Larval host 
plants have been observed to stay green and edible longer when located 
on or near soils recently tilled by gophers (Thomomys bottae) (Singer 
1972, p. 75; Murphy et al. 2004, p. 26). Huenneke et al. (1990, p. 490) 
hypothesized that soil disturbance by gophers may limit the performance 
of grasses similar to results caused by grazing, with grazers reducing 
the standing grass biomass in a system, which allowed the persistence 
of small forbs. Larval host plants that stay green longer into the dry 
season may allow prediapause larva to reach the fourth instar.

Criteria Used To Identify Critical Habitat

    All proposed revised critical habitat units are within areas that 
we have determined were occupied at the time of listing or are 
currently occupied, and that contain sufficient PCEs to support life 
history functions essential for the conservation of the subspecies. 
Lands were proposed for designation based on sufficient PCEs being 
present to support the life processes. Some lands contain only a 
portion of the PCEs necessary to support the particular use of that 
habitat.
    We have defined occupied critical habitat as: (1) Those grasslands 
on serpentine or serpentine-like soils containing the PCEs that were 
occupied by the bay checkerspot butterfly at the time of listing in 
1987 or (2) those grasslands on serpentine or serpentine-like soils 
containing the PCEs that have been occupied since the time of listing. 
Units did not have to contain all PCEs. We used information compiled 
for the proposed and final listing rules, reports prepared by San Mateo 
County Parks, Santa Clara County Parks, the CNDDB, researchers, 
consultants, and published and unpublished literature to identify the 
specific locations occupied by the bay checkerspot butterfly at the 
time of listing and currently occupied.
    The currently occupied habitat for the bay checkerspot butterfly is 
highly fragmented and isolated; the majority of all extant occurrences 
are within an approximate 9 mile (mi) (14.5 kilometer (km)) radius in 
Santa Clara County, California. The population estimates in San Mateo 
County are extremely small and those in Santa Clara County have 
declined significantly in recent years. As a result of population 
declines and fragmented habitats, all areas currently known to support 
the bay checkerspot butterfly are being proposed for designation.
    Several areas occupied by the bay checkerspot butterfly at the time 
of listing are not currently occupied. Some of these areas have been 
surveyed since listing and no bay checkerspot butterflies were 
observed; however, not all of the units have been recently surveyed 
and, due to the metapopulation dynamics of the subspecies, it is 
possible that the subspecies has recolonized some of these areas. The 
metapopulation dynamics of the subspecies has shown that population 
fluctuations occur and extirpation and recolonization is a normal 
occurrence for the bay checkerspot butterfly (Ehrlich et al. 1975, pp. 
221-228; 1980; Harrison 1994, pp. 111-128). The units that have been 
surveyed since the time of listing without observations of the 
subspecies include San Bruno Mountain, Pulgas Ridge, and Jasper Ridge 
Biological Preserve in San Mateo County, California. These areas are 
proposed for designation as critical habitat because they were all 
occupied at the time of listing and designation of these units will 
reduce the likelihood of extinction by providing source/sink (larger 
patches of high-quality habitat/small patches of marginal habitat/) 
areas and ``stepping stone'' (often smaller, unconnected areas that 
bridge the distance between larger blocks of suitable habitat) habitats 
for the subspecies. Since the bay checkerspot butterfly is susceptible 
to extreme weather events these additional units in San Mateo County 
will also reduce the risk of extinction from stochastic natural events, 
extreme weather conditions, and help to ensure survival of the 
subspecies by providing potential dispersal habitat for individuals 
that were reintroduced to Edgewood Park early in 2007.
    The distribution of proposed critical habitat areas (occupied and 
currently unoccupied) was selected to help reduce the level of habitat 
fragmentation within the geographic range of the bay checkerspot 
butterfly by providing dispersal and recolonization opportunities for 
the subspecies. The butterfly is considered relatively sedentary 
(Ehrlich 1965, p. 333; Harrison 1989, p. 50-51; Singer and Hanski 2004, 
p. 187) and reduced fragmentation should facilitate movements between 
habitat patches. McKechnie et al. (1975, p. 561) observed that out of 
several years of mark recapture studies only 1.7 percent of males and 
4.8 percent of females moved a distance of approximately 1,600 feet 
(ft.) (500 meter (m)). These figures are consistent with observations 
made by Weiss (1996, p. 93) who reported that adult movement declined 
with increasing distance with only about 5

[[Page 48185]]

percent moving between 656 to 984 ft (200 to 300 m).
    Although the butterfly is considered sedentary, long-distance 
movements have been documented. The longest documented movements 
observed by Harrison (1989, p. 1239) were 3.5 mi (5.6 km) for one male 
and 2 mi (3.2 km) for one female. Murphy (Service 2001, p. 21451) 
reported movement of bay checkerspot butterflies of 4.7 mi (7.6 km). 
Harrison et al. (1988, p. 371) hypothesized that habitats greater than 
4.3 to 5.0 mi (7 to 8 km) from a source population (Coyote Ridge in the 
study) were unlikely to ever sustain populations of the bay checkerspot 
butterfly. This hypothesis was based on the presence or absence of 
adult bay checkerspot butterflies in Santa Clara County in apparently 
suitable habitat and their relative distance from Coyote Ridge. The 
study was not designed to predict the bay checkerspot butterfly's upper 
limit of dispersal. Harrison (1989, p. 371) hypothesized that the rate 
of colonization, relative to the rate of extinction, was too low to 
maintain populations of the bay checkerspot butterfly on distant 
habitat patches (distant from a source patch). Given the subspecies' 
historical distribution, its metapopulation dynamics, and its sedentary 
tendencies, reducing habitat fragmentation, by designating occupied and 
currently unoccupied habitat that provide quality stepping stone 
habitat, will increase the likelihood of recolonization of more distant 
patches of suitable habitat.
    We have determined that, due to the limited availability of habitat 
for the subspecies, its limited distribution, and its generally low 
dispersal tendencies, the long-term conservation of the bay checkerspot 
butterfly is dependent upon the protection of habitat that was occupied 
at the time of listing as well as habitat that is currently occupied. 
The presence of all six PCEs was not a requirement to designating a 
unit as critical habitat; however, all twelve units currently support 
all six PCEs.

Mapping

    Geospatial datasets were used within ArcGIS/ArcMap 9.2 
(Environmental Systems Research Institute, Redlands, California) and 
analyzed to define the areas that best contain the features that are 
essential to the conservation of the bay checkerspot butterfly. To 
delineate the proposed units of occupied critical habitat, we plotted 
all occurrence records of bay checkerspot butterfly known at the time 
of listing or currently known on maps as polygons. We then examined 
whether these areas supported the PCEs.
    When determining the proposed revisions to critical habitat 
boundaries within this proposed rule, we made every effort to avoid 
including developed areas such as buildings, paved areas, and other 
structures that lack PCEs for the bay checkerspot butterfly. The scale 
of the maps we prepared under the parameters for publication within the 
Code of Federal Regulations may not reflect the exclusion of such 
developed areas. Any such structures and the land under them 
inadvertently left inside critical habitat boundaries shown on the maps 
of this proposed revision to critical habitat have been excluded by 
text in this proposed rule and are not proposed for designation as 
critical habitat. Therefore, Federal actions limited to these areas 
would not trigger section 7 consultation, unless they may affect the 
subspecies or primary constituent elements in adjacent critical 
habitat.
    We are proposing to revise the critical habitat designation on 
lands that we have determined were occupied at the time of listing or 
are currently occupied and contain sufficient primary constituent 
elements to support life-history functions essential for the 
conservation of the subspecies.
    The units being proposed for revised designation are based on 
sufficient PCEs being present to support bay checkerspot butterfly life 
processes. Some units contain all PCEs and support multiple life 
processes. Some units contain only a portion of the PCEs necessary to 
support the bay checkerspot butterfly particular use of that habitat. 
Where a subset of the PCEs is present (such as presence of larval host 
plants, adult nectar plants, and grasslands with varied topography), it 
has been noted that only PCEs present at designation would be 
protected.
    Section 10(a)(1)(B) of the Act authorizes us to issue permits for 
the take of listed animal species incidental to otherwise lawful 
activities. An incidental take permit application must be supported by 
a habitat conservation plan (HCP) that identifies conservation measures 
that the permittee agrees to implement to minimize and mitigate the 
impacts on the species by the requested incidental take. We often 
exclude non-Federal public lands and private lands that are covered by 
an existing operative HCP and executed implementation agreement (IA) 
under section 10(a)(1)(B) of the Act from designated critical habitat 
because the benefits of exclusion outweigh the benefits of inclusion as 
discussed in section 4(b)(2) of the Act. To date, Pacific Gas and 
Electric's Metcalf Evendale/Monta Vista Line is the only HCP that has 
been completed that includes the bay checkerspot butterfly as a covered 
species. The HCP was issued in 1998 and was in effect for a period of 3 
years, and covered approximately 4 ac (1.6 ha). Because the HCP has 
expired, we are not proposing to exclude lands once covered under this 
HCP. The San Bruno Mountain HCP (SBMHCP) Amendment 5 would add the 
Callippe silverspot butterfly (Speyeria callippe callippe) and the bay 
checkerspot butterfly to the existing HCP. The Callippe silverspot 
butterfly shares some habitat requirements similar to the bay 
checkerspot butterfly, specifically the use of open grasslands. We are 
proposing to exclude Unit 1 from critical habitat based on the 
development of amendment 5 of the SBMHCP (See Application of Section 
4(b)(2) of the Act). Stanford University is in the process of 
developing an HCP for lands owned by Stanford University, which 
includes the Jasper Ridge Biological Preserve (Unit 4); however as 
currently proposed, this HCP would not include the bay checkerspot 
butterfly or any other butterfly species, so this HCP is not being 
proposed for exclusion. Santa Clara County is currently in the early 
stages of developing a regional HCP that would encompass the majority 
of Santa Clara County, including all proposed critical habitat units in 
the county (Units 5 through 12); this HCP is still in the early stages 
of development, but as proposed would include the bay checkerspot 
butterfly. However, the Santa Clara County HCP is not expected to be 
finalized for several years. We are seeking comments regarding areas 
that have management plans or HCPs that may potentially be excluded 
from the critical habitat designation (see Public Comments Solicited 
section above).

Summary of Changes From Previously Designated Critical Habitat

    The areas identified in this proposed rule constitute a proposed 
revision from the areas we designated as critical habitat for bay 
checkerspot butterfly on April 30, 2001 (66 FR 21450). The primary 
differences include the following:
    (1) The 2001 critical habitat rule (66 FR 21450) consisted of 15 
units comprising a total of 23,903 ac (9,673 ha). This proposed 
revision includes 12 units comprising a total of 19,746 ac (7,990 ha). 
The majority of the proposed units correspond to those in the 2001 
designation. However, we have refined the units to eliminate areas that 
are unlikely to support the PCEs such as areas that are forested or 
have since been developed. The unit formerly designated as 
Communications Hill (2001 unit 6) is not included in this

[[Page 48186]]

proposed rule because that unit has since been developed to a large 
degree and the remaining habitat has been degraded by the invasion of 
nonnative and invasive grasses and is unlikely to support sufficient 
PCEs to meet one or more of the life-history requirements of the 
subspecies. In addition, the Pulgas Ridge unit (proposed unit 2) is new 
in this proposed designation and is included because it represents an 
area that was historically known to support the subspecies, is 
currently undeveloped, is expected to serve as a ``stepping stone'' 
between the two southern units in San Mateo County (proposed units 4 
and 5) and the San Bruno Mountain unit (proposed Unit 1), and can 
provide additional habitat to support a core population in San Mateo 
County. Currently the distance between proposed Unit 1 and proposed 
Unit 2 is greater than the published dispersal distance of the bay 
checkerspot butterfly; however, a number of small and fragmented 
patches of intervening grasslands occur along the Interstate 280 
corridor between proposed Unit 1 and 2 that would be expected to serve 
as additional stepping stones to potentially allow for movement between 
these two units. The numerous small patches of grassland habitat 
between units are not proposed to be designated as critical habitat 
because the Service has no information regarding the presence of 
sufficient PCEs within these areas.
    (2) We propose to revise the PCEs and exclude ``pollinators of the 
bay checkerspot butterfly's food and nectar plants'' because the 
specific pollinators of each host and nectar plant are not known and 
the presence of the plants themselves implies their successful 
reproduction. We clarify ``topography with varied slopes and aspects'' 
by defining those slope aspects that were important as well as defining 
warm versus cool slopes. We expand the previous PCE regarding 
``wetlands that provide moisture'' to reflect the range of water 
sources that may be used by the subspecies, such as the banks of 
streams and lakes. To provide for greater specificity we remove ``space 
for dispersal between habitable areas'' and include ``annual and 
perennial grasslands'' along with a description of that habitat type 
and plant species commonly found in them. We replace ``stands of'' the 
larval host plants with ``presence of'' because the density of host 
plants needed to support the subspecies has not been widely researched 
and does not appear in the literature, and thus is difficult to 
quantify at this time. Finally, to provide for greater specificity, we 
expand the previous PCE regarding soils to include a list of soils that 
are associated with serpentine or serpentine-like habitats.
    (3) We updated areas that are currently known to support 
populations of the bay checkerspot butterfly, as well as areas where 
the subspecies has since become extirpated. The number of known 
occurrences has continued to decline since the 2001 designation of 
critical habitat.

Proposed Revisions to the Critical Habitat Designation

    We are proposing 12 units as critical habitat for the bay 
checkerspot butterfly. These units, which generally correspond to those 
units in the 2001 designation, if finalized, would entirely replace the 
current critical habitat designation for the bay checkerspot butterfly 
in 50 CFR 17.95(i). The critical habitat areas we describe below 
constitute our current best assessment of areas that meet the 
definition of critical habitat for the bay checkerspot butterfly. The 
12 areas designated as critical habitat are: (1) San Bruno Mountain, 
(2) Pulgas Ridge, (3) Edgewood Park, and (4) Jasper Ridge in San Mateo 
County; and (5) Coyote Ridge (A and B), (6) Tulare Hill, (7) Santa 
Teresa Hills, (8) Calero Reservoir, (9) Kalana Hills (A and B), (10) 
Morgan Hill, (11) Bear Ranch, and (12) San Martin in Santa Clara 
County. The approximate area encompassed within each proposed critical 
habitat unit is shown in Table 2. Of the 19,746 ac (7,990 ha) being 
proposed as revised critical habitat, we are proposing to exclude 
approximately 775 ac (314 ha) from the final critical habitat 
designation under section 4(b)(2) of the Act.