Endangered and Threatened Wildlife and Plants; Revised Critical Habitat for the California Red-Legged Frog (Rana aurora draytonii), 53492-53680 [E8-20473]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 73, Number 180 (Tuesday, September 16, 2008)]
[Proposed Rules]
[Pages 53492-53680]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-20473]



[[Page 53491]]

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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; Revised Critical Habitat 
for the California Red-Legged Frog (Rana aurora draytonii); Proposed 
Rule

Federal Register / Vol. 73, No. 180 / Tuesday, September 16, 2008 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[FWS-R8-ES-2008-0089; 92210-1117-0000-B4]
RIN 1018-AV90


Endangered and Threatened Wildlife and Plants; Revised Critical 
Habitat for the California Red-Legged Frog (Rana aurora draytonii)

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 designated critical habitat for the California red-legged frog 
(Rana aurora draytonii), pursuant to the Endangered Species Act of 
1973, as amended (Act). The previous final rule designated 450,288 
acres (ac) (182,225 hectares (ha)) of critical habitat. We herein 
propose to revise those critical habitat boundaries to better reflect 
lands containing essential features for the California red-legged frog, 
and we now propose to designate approximately 1,804,865 ac (730,402 ha) 
of critical habitat in 28 California counties, an increase of 
approximately 1,354,577 ac) (548,177 ha).

DATES: We will accept comments from all interested parties until 
November 17, 2008. We must receive requests for public hearings, in 
writing, at the address shown in the FOR FURTHER INFORMATION CONTACT 
section by October 31, 2008.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Follow the instructions for submitting comments.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: FWS-R8-ES-2008-0089; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203. We will not accept e-mail or faxes. We 
will post all comments on https://www.regulations.gov. This generally 
means that we will post any personal information you provide us (see 
the Public Comments section below for more information).

FOR FURTHER INFORMATION CONTACT: For general information on the 
proposed designation and information about the proposed revised 
designation in Alameda, Butte, Calaveras, Contra Costa, El Dorado, 
Kern, Kings, Marin, Mendocino, Merced, Napa, Nevada, Placer, San 
Joaquin, San Mateo, Santa Clara, Solano, Sonoma, Stanislaus, and Yuba 
Counties, contact Susan Moore, Field Supervisor or Arnold Roessler, 
Listing Program Coordinator, U.S. Fish and Wildlife Service, Sacramento 
Fish and Wildlife Office, 2800 Cottage Way, Room W-2605, Sacramento, CA 
95825; telephone 916/414-6600; or 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.
    For information about the proposed designation in Los Angeles, 
Monterey, San Benito, San Luis Obispo, Santa Barbara, Santa Cruz, and 
Ventura Counties, contact Diane Noda, Field Supervisor, Ventura Fish 
and Wildlife Office, U.S. Fish and Wildlife Service, 2394 Portola Road, 
Suite B, Ventura, CA 93003; telephone 805/644-1766; facsimile 805/644-
3958.
    For information about the proposed designation in Riverside County, 
contact Jim Bartel, Field Supervisor, Carlsbad Fish and Wildlife 
Office, U.S. Fish and Wildlife Service, 2730 6010 Hidden Valley Road, 
Carlsbad, CA 92009; telephone 760/431-9440; facsimile 760/431-9624.

SUPPLEMENTARY INFORMATION:

Public Comments

    We intend any final action resulting from this proposal to be as 
accurate and as effective as possible. Therefore, we request comments 
or suggestions on this proposed rule. We particularly seek comments 
concerning:
    (1) The reasons why we should or should not revise the designation 
of habitat as ``critical habitat'' under section 4 of the Act (16 
U.S.C. 1531 et seq.), including whether the benefit of designation 
would outweigh threats to the species caused by the designation, such 
that the designation of critical habitat is prudent;
    (2) Specific information on:
     The amount and distribution of California red-legged frog 
habitat,
     What areas containing features essential to the 
conservation of the species we should include in the designation and 
why, and
     What areas are not essential for the conservation of the 
species and why;
    (3) Land-use designations and current or planned activities in the 
subject areas and their possible effects on proposed critical habitat;
    (4) Comments or information that may assist us in identifying or 
clarifying the primary constituent elements;
    (5) How the proposed revised critical habitat boundaries could be 
refined to more closely circumscribe the landscapes identified as 
essential;
    (6) Whether the lands proposed as critical habitat on Department of 
Defense land at Vandenberg Air Force Base in Santa Barbara County and 
Camp San Luis Obispo in San Luis Obispo County should be exempted under 
section 4(a)(3) or excluded under section 4(b)(2) of the Act;
    (7) Whether the U.S. Forest Service lands managed under the Sierra 
Nevada Forest Plan Amendment within the units being proposed as 
critical habitat should be excluded under section 4(b)(2) of the Act;
    (8) Whether Unit CAL-1 (Young's Creek) in Calaveras County should 
be excluded under section 4(b)(2) of the Act;
    (9) Any foreseeable economic, national-security, or other potential 
impacts resulting from the proposed revised designation and, in 
particular, any impacts on small entities, and the benefits of 
including or excluding areas that exhibit these impacts;
    (10) Information on any quantifiable economic costs or benefits of 
the revised designation of critical habitat; and
    (11) Whether we could improve or modify our approach to designating 
critical habitat in any way to provide for greater public participation 
and understanding, or to better accommodate public concerns and 
comments.
    Our final determination concerning critical habitat will take into 
consideration all written comments and any additional information we 
receive during the comment period. On the basis of public comments, we 
may, during the development of our final designation, find that areas 
proposed are not essential, are appropriate for exclusion under section 
4(b)(2) of the Act, or are not appropriate for exclusion.
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section. We will not 
consider comments sent by e-mail or fax or to an address not listed in 
the ADDRESSES section.
    If you submit a comment via https://www.regulations.gov, your entire 
comment--including any personal identifying information--will be posted 
on the Web site. If you submit a hardcopy comment that includes 
personal identifying information, you may request at the top of your 
document that we withhold this information from public review. However, 
we cannot guarantee that we will be able to do so. We will post all 
hardcopy comments on https://www.regulations.gov.

[[Page 53493]]

Background

    It is our intent to discuss only those topics directly relevant to 
the revised designation of critical habitat in this proposed rule. For 
more information on the California red-legged frog, refer to the 
listing rule and previous determination of critical habitat published 
in the Federal Register on May 23, 1996 (61 FR 25813), and April 13, 
2006 (71 FR 19243), respectively.

Subspecies Description

    The California red-legged frog is the largest native frog in the 
western United States. It is endemic (native and restricted) to 
California and Baja California, Mexico, at elevations ranging from sea 
level to approximately 5,000 feet (ft) (1,500 meters (m)). The 
California red-legged frog gains its name from the typically red or 
pink color of its posterior abdomen and hind legs. The California red-
legged frog is one of two subspecies of the red-legged frog (Rana 
aurora). For a detailed description of the subspecies, see the Recovery 
Plan for the California Red-legged Frog (Service 2002, pp. 1-173) and 
references identified within the plan as well as information in 
previous Federal Register notices (69 FR 19620; 66 FR 14626; 61 FR 
25813).

Life History

    During breeding season, which typically runs from November through 
April, males call to females from the margins of ponds and slow streams 
(Jennings et al. 1992, p. 3). Actual mating most commonly occurs in 
March, but can vary depending on seasonal climatic patterns. The female 
lays a jellylike mass of 2,000 to 5,000 reddish brown eggs in the water 
attached to some brace such as emergent vegetation, twigs, or other 
structure. The resulting tadpoles, which likely feed on algae (Dickman, 
1968, pp. 1189-1190), typically require about 3 weeks to hatch, and 
another 11 to 20 weeks to metamorphose into juvenile frogs. 
Metamorphosis, therefore, typically occurs from July to September, 
although some tadpoles have been observed to delay metamorphosis until 
the following March or April (Bobzien et al. 2000, p. 13; Fellers et 
al. 2001, pp. 156-157). Adults tend to be nocturnal, while juveniles 
can be active at any time of day (Hayes and Tennant 1985, p. 604).

Geographic Range

    The historical range of the California red-legged frog was thought 
to extend from Sonoma County, California, south along the coast to 
northwestern Baja California, Mexico, and inland as far as the vicinity 
of Redding in Shasta County, CA, south along the Sierra Nevada and the 
Central Valley (Storer 1925, pp. 235-236; Jennings and Hayes 1985, pp. 
94-95; Hayes and Krempels 1986, pp. 930, 933-935). The range of the 
California red-legged frog has declined since being described by Storer 
(1925, pp. 235-236). Through comparison of historical museum records 
(1890 to 1980) and field surveys (1990 to 1992), Fisher and Shaffer 
(1996, pp. 1391-1392) present evidence of the extirpation (local 
extermination) of California red-legged frogs from 24 of 28 counties in 
a limited portion of its historical range. In 1996, when the subspecies 
was listed, 243 streams or drainages in 22 California counties were 
documented to contain populations of California red-legged frogs 
(California Natural Diversity Database (CNDDB) 2008). At the time of 
listing, California red-legged frogs were believed to have been 
extirpated from most of the southern Coastal Mountains from Santa 
Barbara south to Baja California and east along the Transverse (San 
Gabriel, San Bernardino, Santa Ynez, and Santa Monica Mountains) and 
Peninsular Ranges (San Jacinto, Santa Rosa, Agua Tibia, Laguna, Santa 
Ana Mountains). Since listing, two additional occurrences have been 
discovered south of the Tehachapi Mountains (CNDDB 2008) but may no 
longer be extant. Recent genetic studies have identified that the 
subspecies extends north along the coast into Mendocino County, 
California (Shaffer et al. 2004, pp. 2676-2677). Five additional 
occurrences have been recorded in the Sierra Nevada foothills, bringing 
the total to six known populations, compared to approximately 26 
historical records for the Sierra Nevada foothills (Berkeley Museum of 
Vertebrate Zoology 2004, pp. 3, 5, 6, 9; CNDDB 2008; California Academy 
of Sciences 2004, p. 12; Barry 2005, p. 1). Currently, California red-
legged frogs are only known from 3 disjunct regions in 28 California 
counties (Sierra Nevada, North and Central Coast Range, and Southern 
California); and are also still present in Baja California, Mexico 
(Grismer 2002 p. 79; Fidenci 2004, pp. 27-29; Smith and Krofta 2005, 
pp. 4, 6).

Habitat

    California red-legged frogs live in a Mediterranean climate, which 
is characterized by temporal and spatial changes in habitat quality. 
During a period of abundant rainfall, almost the entire landscape, 
including breeding ponds and streams, may become suitable habitat for 
the adults. Conversely, habitat use may be drastically confined during 
periods of prolonged drought. Due to this variability, population sizes 
can vary widely from year to year. During favorable years, California 
red-legged frogs can produce large numbers of dispersing young, 
resulting in an increase in the number of occupied sites. In contrast, 
California red-legged frogs may temporarily disappear from an area 
during periods of extended drought. Therefore, it is essential to 
provide for sites that can be recolonized by dispersing individuals 
(Semlitsch 2000, pp. 623, 624).
    The habitats used by this subspecies typically change in extent and 
suitability in response to the dynamic nature of floodplain and fluvial 
processes (i.e., natural water flow and sedimentation regimes that, in 
flux, create, modify, and eliminate deep pools, backwater areas, ponds, 
marshes, and other aquatic habitats). Rangewide, and even within local 
populations, the California red-legged frog uses a variety of areas, 
including various aquatic, riparian, and upland habitats. In some 
cases, they may complete their entire life cycle in a particular 
habitat (i.e., a pond is suitable for all life stages), and in other 
cases, they may seek multiple habitat types depending on climatic 
conditions or distance between and availability of wetland and other 
suitably moist environments.
    Despite the California red-legged frog's ability to utilize 
multiple habitat types, there are certain habitat features they 
require. Most important is a breeding pond or slow-flowing stream reach 
or deep pool within a stream with some type of vegetative or other 
material to attach their egg masses, that holds water long enough for 
tadpoles to complete their metamorphoses into juvenile frogs able to 
survive outside of water. California red-legged frogs often disperse 
from their breeding habitat to utilize various aquatic, riparian, and 
upland summer habitats during their migrations from one area to 
another. However, it is also common for individuals to remain in the 
breeding area on a year-round basis.
    In Northern California, many California red-legged frog populations 
occupy artificial or created wetland environments. Historically, as 
natural wetlands and streams were converted for agriculture, flood 
control, and urban development, California red-legged frogs colonized 
small artificial impoundments, or stock ponds, created by cattle 
ranchers for the purpose of providing water for their cattle. Our 
understanding of the role of stock ponds in the conservation of the 
California red-legged frog has evolved since listing. Without these 
stock ponds, the range of

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the California red-legged frog would be limited further in this region.
    Riparian and upland habitats adjacent to wetland features used by 
the California red-legged frog are essential in maintaining frog 
populations and biodiversity, hydrology and water quality of the 
aquatic feature. Riparian habitat includes vegetation dependent on 
nearby wetted areas for water. Typically such vegetation grows along 
the banks and in the floodplains of streams and ponds. Adjacent uplands 
are marked by vegetation that is not dependent on a nearby supply of 
surface water. Both riparian and upland habitats are used by the 
California red-legged frog for foraging, shelter, cover, and non-
dispersal movement (Service 2002, pp. 14-15; Bulger et al. 2003, p. 87; 
Fellers and Kleeman 2007, p. 276). Bulger et al. (2003, pp. 85-95) 
studied California red-legged frog terrestrial activity in coastal 
forest and grassland habitats and recommended at least a 328 ft (100 m) 
distance for protection of aquatic and upland habitat be provided as 
well as impose seasonal restrictions for activities within this zone. 
In a recent study also specific to the California red-legged frog, 
Fellers and Kleeman (2007, pp. 278-280) recommended establishing zones 
around breeding habitat, non-breeding habitat, and migration corridors 
along with a buffer of these areas that is sufficient to protect 
function of the amphibian habitat. However, Fellers and Kleeman (2007, 
p. 279) discouraged setting specific distances due to differences in 
biological or site-specific requirements and that any distances set for 
avoidance of upland habitat should be made on a case-by-case basis 
taking into account the need to protect the breeding and non-breeding 
habitat as well as any migration corridors.
    Tatarian (2004, p. 33) found California red-legged frogs inhabiting 
upland areas for 50 days at a distance of 302 ft (92 m) from aquatic 
habitat; Bulger et al. (2003, pp. 87-89) found that the subspecies is 
capable of inhabiting upland habitats within 200 ft (60 m) of aquatic 
habitat for continuous durations exceeding 20 days; and Rathbun et al. 
(1993, p. 15) observed a California red-legged frog inhabiting upland 
riparian habitat at distances of up to 85 ft (26 m) for 65 days. 
California red-legged frogs often disperse from their breeding habitat 
to forage and seek suitable upland and riparian habitat if aquatic 
habitat is not available. Such habitat includes structure that provides 
shade, moisture, and cooler temperatures. This structure may be 
natural, such as the spaces under boulders or rocks and organic debris 
(e.g., downed trees or logs), or it could be manmade, such as 
industrial debris and agricultural features (drains, watering troughs, 
abandoned sheds, or stacks of hay or other vegetation). California red-
legged frogs will also use small mammal burrows and moist leaf litter 
as refugia (areas whose climate remains habitable when that of the 
surrounding areas has changed) (Rathbun et al. 1993, p. 15; Jennings 
and Hayes 1994, p. 64; Fellers and Kleeman 2005, p. 12).

Dispersal

    Adult California red-legged frogs may disperse from breeding sites 
at any time of year. Dispersing adult California red-legged frogs in 
northern Santa Cruz County traveled distances from 0.25 miles (mi) (0.4 
kilometers (km)) to more than 2.0 mi (3.2 km) without apparent regard 
to topography, vegetation type, or riparian corridors (Bulger et al. 
2003, p. 90). California red-legged frogs have also been tracked using 
radio telemetry in East Las Virgenes Creek, Ventura County, which is 
characterized by highly variable rainfall (Smith 2005, p. 1). Habitat 
includes a well-defined creek and riparian zone with permanent deep 
pools. The maximum distance moved in this study was 48 ft (15 m) (Smith 
2005, p. 1). In contrast, California red-legged frog movements in Santa 
Cruz County were found to be substantially less, with typical movements 
of 9 to 16 ft (3 to 5 m) from the water's edge. Many newly 
metamorphosed juveniles tend to disperse short distances initially from 
July through September, and then move farther away from the breeding 
habitat during warm rain events (Jennings 2000, p. 1). Bobzien et al. 
(2000, p. 12) observed juveniles inhabiting a wide variety of habitats 
while adults primarily inhabited deep pools. They postulated that 
juveniles might segregate themselves away from adults to escape 
predation and competition. In a study in Marin County, California, 123 
frogs were tracked using radio telemetry between 1997 and 2003 at 8 
different sites within the Point Reyes National Seashore and Golden 
Gate National Recreation Area (Fellers and Kleeman 2007, p. 277). The 
habitat at the sites included permanent ponds, seasonal ponds, 
permanent marsh, and a seasonal seep. The majority of movement was 
small scale (less than 98 ft (30 m)) and considered non-dispersal. 
Movements of greater than 98 ft (30 m) occurred mostly during winter 
rain events; however, some movements did occur when the ponded habitat 
was almost dry (Fellers and Kleeman 2007, p. 279). The majority of 
frogs dispersed less than 1,640 ft (500 m) away from breeding habitat, 
and the maximum dispersal distance recorded was 1.7 mi (2.8 km) 
(Fellers and Kleeman 2007, pp. 279-280). The study concluded that most 
frogs move away from breeding sites, but only a few disperse farther 
than the nearest non-breeding habitat; and that the distance moved is 
highly dependent on site conditions and local landscapes (Fellers and 
Kleeman 2007, p. 284). The study also recommended that average 
dispersal or migration distances not be used, and to let site 
conditions dictate the amount of area needed for the species. The study 
also concluded that, by establishing a generic dispersal distance, we 
may be selecting for sedentary frogs; losing those individuals that 
disperse farthest and reach other distant breeding sites would decrease 
genetic exchange and diversity (Fellers and Kleeman 2007, p. 285).
    For reasons that are currently unclear, juveniles tend to disperse 
away from aquatic habitat occupied by adults. Juvenile dispersal is 
essential for recolonizing temporarily extirpated habitat and 
preventing genetic isolation because juveniles disperse in more 
directions, and for longer distances than do migrating adults (Wright 
1999, p. 2; Bulger et al. 2003, p. 94). Dispersal habitat for juveniles 
can be almost anything that provides sheltering vegetation or scattered 
wetlands or streams. This includes forested areas, nonnative 
grasslands, and even croplands or pasture, but is not known to include 
urbanized or suburban areas, suburban developments, or areas separated 
from breeding habitat by impassible barriers. Impassible barriers 
include wide or fast-flowing rivers and streams, lakes greater than 50 
ac (20 ha), and heavily traveled roads without underpasses or culverts 
(Reh and Seitz 1990, pp. 247, 248; Fahrig et al. 1995, 179-181). 
Passable roadways that are heavily used by vehicles may also result in 
a high rate of mortality for frogs and other amphibians, thereby 
limiting dispersal capabilities (Glista et al. 2008, pp. 81-82). 
Juveniles dispersing along riparian corridors may have higher 
survivorship, as sheltering vegetation and suitable aquatic habitat are 
both more common in such corridors (Jennings 2000, p. 1). Juveniles 
appear to have less strict requirements for aquatic habitat than 
adults, and tend to segregate away from adults in water bodies that are 
shallower or faster moving than those typically used for breeding 
(Hayes and Jennings 1988, p. 147; Bobzien 2000, p. 1; M. Jennings 2000, 
p. 1).
    The long-term probability of the survival and recovery of 
California red-legged frogs is dependent upon the protection of 
existing breeding habitat

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and associated uplands (Fellers and Kleeman 2005, pp. 1, 17-18), the 
movements of individuals between aquatic patches, and the ability to 
recolonize newly created or vacated habitats. Recolonization, which is 
vital to the recovery of this subspecies, is dependent upon landscape 
characteristics, including appropriate distances between suitable 
breeding and non-breeding aquatic habitat, and limited fragmentation of 
interconnecting habitat (Vos and Chardon 1998, pp. 44, 53-56).

Previous Federal Action

    On April 13, 2006 (71 FR 19243), we published our final designation 
of critical habitat for the California red-legged frog. On July 20, 
2007 (Service 2007a, pp. 1-2), we announced that we would review the 
April 13, 2006, final rule after questions were raised about the 
integrity of scientific information used and whether the decision made 
was consistent with the appropriate legal standards. Based on our 
review of the previous final critical habitat designation, we 
determined it was necessary to revise critical habitat and this rule 
proposes those revisions. On December 12, 2007, the Center for 
Biological Diversity filed a complaint in the U.S. District Court for 
the Northern District of California challenging our designation of 
critical habitat for the California red-legged frog (Center for 
Biological Diversity v. Kempthorne, et al., Case No. C-07-6404-WHA). On 
April 2, 2008, the court entered a consent decree requiring a proposed 
revised critical habitat rule to be submitted to the Federal Register 
by August 29, 2008, and a final revised critical habitat designation to 
be submitted to the Federal Register by August 31, 2009.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as:
    (1) 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
    (a) essential to the conservation of the species and
    (b) that may require special management considerations or 
protection; and
    (2) 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 the government or public to access private lands. Such 
designation does not require implementation of restoration, recovery, 
or enhancement measures by private landowners. Where the landowner 
requests Federal agency funding or authorization of an activity that 
may affect a listed species or critical habitat, the consultation 
requirements of section 7 would apply, but even in the event of a 
destruction or adverse modification finding, the landowner's obligation 
is not to restore or recover the species, but to implement reasonable 
and prudent alternatives to avoid destruction or adverse modification 
of critical habitat.
    For inclusion in a critical habitat designation, habitat within the 
geographical area occupied by the species at the time it was listed 
must contain the physical and biological features that are essential to 
the conservation of the species, and be included only if those features 
may require special management considerations or protection. 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 PCEs laid out 
in the appropriate quantity and spatial arrangement for the 
conservation of the species). Under the Act, we can designate critical 
habitat in areas outside the geographical area occupied by the species 
at the time it is listed only when we determine that those areas are 
essential to the conservation of 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 decisions are based on 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 revised critical 
habitat, our primary source of information is generally the information 
developed during the listing process 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, based on scientific data not now available to the 
Service, 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 of the species.
    Areas that support populations of the California red-legged frog, 
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 plans (HCPs), section 7 
consultations, or other species conservation planning efforts if new 
information calls for a different outcome.

[[Page 53496]]

Methods

    As required by section 4(b) of the Act, we used the best scientific 
and commercial data available in determining areas occupied at the time 
of listing that contain the features essential to the conservation of 
the California red-legged frog. We have reviewed the approach to the 
conservation of the California red-legged frog provided in its recovery 
outline (Service 2002, pp. 1-173) and information from State, Federal, 
and Tribal agencies, and from academia and private organizations that 
have collected scientific data on the California red-legged frog. This 
includes information used to prepare the 2006 designation of critical 
habitat (71 FR 19243), the Recovery Plan for California red-legged frog 
(Service 2002, pp. 1-173), the CNDDB, published and unpublished papers, 
reports, academic theses, 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.

Primary Constituent Elements

    In accordance with section 3(5)(A)(i) of the Act and regulations at 
50 CFR 424.12(b), in determining which areas to propose as revised 
critical habitat, we consider the physical and biological features that 
are essential to the conservation of the species that may require 
special management considerations or protection. We consider the 
physical and biological features to be the PCEs laid out in the 
appropriate quantity and spatial arrangement for conservation of the 
species. These include, but are not limited to:
    (1) Space for individual and population growth and for normal 
behavior;
    (2) Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    (3) Cover or shelter;
    (4) Sites for breeding, reproduction, and rearing (or development) 
of offspring; and
    (5) Habitats that are protected from disturbance or are 
representative of the historical geographical and ecological 
distributions of a species.
    We derive the PCEs required for California red-legged frog from its 
biological needs. The area proposed for designation as revised critical 
habitat provides aquatic habitat for breeding and non-breeding 
activities and upland habitat for shelter, foraging, predator 
avoidance, and dispersal across the California red-legged frog's range. 
The primary constituent elements and, therefore, the resulting physical 
and biological features essential for the conservation of the species 
were determined from studies of California red-legged frog ecology as 
described in the Background sections of this proposal and in the final 
listing rule published in the Federal Register on May 23, 1996 (61 FR 
25813).

Aquatic Breeding Habitat

    Aquatic breeding habitat is essential for providing space, food, 
and cover necessary to sustain all life stages of California red-legged 
frogs. It consists of low-gradient fresh water bodies, including 
natural and manmade (e.g., stock) ponds, backwaters within streams and 
creeks, marshes, lagoons, and dune ponds. It does not include deep 
lacustrine water habitat (e.g., deep lakes and reservoirs 50 ac (20 ha) 
or larger in size).
    To be considered essential breeding habitat, the aquatic feature 
must have the capability to hold water for a minimum of 20 weeks in all 
but the driest of years. This is the average amount of time needed for 
egg and tadpole development and metamorphosis so that juveniles can 
become capable of surviving in upland habitats. Drying of the aquatic 
habitat after that time can be beneficial because it helps prevent the 
establishment of predatory fish or bullfrogs (Hayes and Jennings 1988, 
p. 152; Cook 1997, pp. ii, iii, 17-19; Scott 1998, p. 3; Cook and 
Jennings 2007, p. 438). Water quality requirements for eggs and 
tadpoles include low salinity (below 4.5 parts per thousand (ppt) for 
eggs, up to 7.0 ppt for tadpoles) (Jennings and Hayes 1990, pp. 18, 19; 
Jennings 1994, p. 1), and temperatures below about 73[deg] Fahrenheit 
(23[deg] Celsius) (Cook 1997, p. 16; Nussbaum et al. 1983, p. 160). 
Water bodies free of bullfrogs and nonnative predatory fish are 
optimal, but California red-legged frog populations can persist in the 
presence of one or the other of these predators (Kiesecker and 
Blaustein 1998, pp. 776, 782; Lawler et al. 1999, pp. 613, 619-621; 
Cook and Jennings 2007, p. 438).
    Adult California red-legged frogs can survive in moist upland areas 
after breeding habitat has dried, and can live several years to make 
new breeding attempts. Therefore, aquatic breeding habitat need not be 
available every year, but it must be available often enough and for 
appropriate hydroperiods to maintain a California red-legged frog 
population during most years. Without aquatic breeding habitats, the 
California red-legged frog would not survive, reproduce, develop 
juveniles, and grow into adult California red-legged frogs that can 
complete their life cycles.

Non-Breeding Aquatic and Riparian Habitat

    Non-breeding aquatic and riparian habitat is essential for 
providing the space, food, and cover necessary to sustain California 
red-legged frogs. Non-breeding aquatic habitat consists of any 
typically shallow (non-lacustrine) freshwater features not suitable as 
breeding habitat, such as streams, small seeps, and ponds that dry too 
quickly to support breeding. Riparian habitat consists of vegetation 
growing nearby, but not typically in, a body of water on which it 
depends. Typically riparian habitat extends from the bank of a pond or 
stream to the margins of the associated floodplain.
    California red-legged frogs can use large cracks in the bottom of 
dried ponds as refugia to maintain moisture and avoid heat and solar 
exposure (Alvarez 2004, p. 162). Fellers and Kleeman (2007, p. 279) 
found that most California red-legged frogs leave their breeding 
habitat once breeding is completed and disperse to other non-breeding 
habitat locations. Without these non-breeding aquatic features, 
California red-legged frogs would not be able to survive drought 
periods, or be able to disperse to other breeding habitat.

Upland Habitat

    Upland habitats associated with riparian and aquatic habitat are 
essential to maintain California red-legged frog populations. This 
habitat type provides food and shelter sites for California red-legged 
frogs and assists in maintaining the integrity of aquatic sites by 
protecting them from disturbance and supporting the normal functions of 
the aquatic habitat. Upland habitat associated with occupied wetland 
habitat often contains blackberry (Rubus spp.), poison oak 
(Toxicodendron diversilobum), coyote brush (Baccharis pilularis), and 
other upland perennial species that provide for foraging habitat and 
shelter from predatory species (Service 2002, pp. 12-14; Fellers and 
Kleeman 2007, pp. 276-277).
    Upland habitat that contains the features essential to the 
conservation of the subspecies consists of natural areas near the edge 
of the riparian vegetation or the edge of the watershed boundary, and 
includes the dispersal corridor between breeding and non-breeding 
aquatic habitat. This is based on the dispersal capabilities of the 
subspecies (see Dispersal Habitat below), and research identifying the 
use of upland

[[Page 53497]]

areas by the subspecies (Rathbun et al. 1993, pp. 15, 16; Bulger et al. 
2003, pp. 93, 94; Tatarian 2004, pp. 24, 25; Fellers and Kleeman 2007, 
p. 279). Tatarian (2004, p. 22) found California red-legged frogs 
inhabiting upland areas for 50 days at a distance of 302 ft (92 m) from 
aquatic habitat; Bulger et al. (2003, pp. 87, 88) found that the 
subspecies is capable of inhabiting upland habitats within 200 ft (60 
m) of aquatic habitat for continuous durations exceeding 20 days; and 
Rathbun et al. (1993, pp. 15, 16) observed California red-legged frogs 
inhabiting upland riparian habitat for durations up to 77 days. 
California red-legged frogs often disperse from their breeding habitat 
to forage and seek suitable upland habitat if aquatic habitat is not 
available.
    As stated above, California red-legged frogs have been documented 
to disperse from ponds and streams a distance over 2.0 mi (3.2 km) 
(Bulger et al. 2003, p. 90). However, based on a review of the most 
current literature and information gathered in development of the 
Recovery Plan for the subspecies, we have determined that the 2.0-mile 
(3.2-km) distance is toward the maximum dispersal distance for the 
subspecies during a single season, and that the 1-mile (1.6-km) 
distance is more reflective of the average dispersal distance for the 
California red-legged frog (Rathbun et al. 1993, pp. 15, 16; Wright 
1999, pp. 1, 2; Bulger et al. 2003, p. 90; Tatarian 2004, table 9; 
Fellers and Kleeman 2005, pp. 14-16; Fellers and Kleeman 2007, pp. 276-
286). Although the studies discussed above provide an approximation of 
the distances that California red-legged frogs can move from their 
aquatic habitats, breeding ponds, and other wetland habitats in search 
of suitable upland refugia or other breeding locations, we recognize 
that upland habitat features will influence California red-legged frog 
movements in a particular landscape and as a result the amount of 
upland habitat surrounding the aquatic breeding and non-breeding 
habitat (PCEs 1 and 2) would be limited to 1 mile (1.6 km) in most 
cases depending on surrounding landscape and dispersal barriers.
    Upland habitat used by the California red-legged frog includes 
structures that provide shade, moisture, and cooler temperatures. These 
structures may be natural, such as the spaces under boulders or rocks 
and organic debris (e.g., downed trees or logs), or it could be 
manmade, such as industrial debris and agricultural features (drains, 
watering troughs, abandoned sheds, or stacks of hay or other 
vegetation). California red-legged frogs will also use small mammal 
burrows and moist leaf litter as refugia (Jennings and Hayes 1994, p. 
64; Fellers and Kleeman 2005, p. 12).

Dispersal Habitat

     Dispersal habitat provides connectivity among California red-
legged frog breeding (and associated upland) habitat patches. While 
California red-legged frogs can pass many obstacles, and do not require 
a particular type of habitat for dispersal, the habitat connecting 
breeding locations and other aquatic habitat must be free of barriers 
that prevent California red-legged frogs from dispersing.
    Designated dispersal habitat consists of upland and riparian 
habitat contiguous with breeding and non-breeding aquatic habitat, that 
is free of barriers, and connects two or more patches of aquatic 
breeding habitat within 1 mi (1.6 km) of one another. Dispersal 
barriers include heavily traveled roads (Vos and Chardon 1998, pp. 44, 
54; Glista et al. 2008, pp. 81-82) that possess no bridges or culverts, 
moderate- to high-density urban or industrial developments with large 
expanses of asphalt or concrete that do not contain the PCEs or 
features essential to conservation of the subspecies, and large 
reservoirs over 50 ac (20 ha) in size that contain predatory species. 
Agricultural lands such as row crops, orchards, vineyards, and pastures 
do not constitute barriers to California red-legged frog dispersal.
    California red-legged frogs have been documented to travel as far 
as 2.2 mi (3.6 km) from non-breeding to breeding habitats (Bulger et 
al. 2003, p. 90). These long-distance movements are most likely 
migrations rather than use of corridors for moving between habitats 
(Scott and Rathbun 1998, pp. 2, 3). These movements have also been 
found to be with apparent disregard to topography, vegetation type, or 
riparian corridors (Bulger et al. 2003, pp. 93, 94; Fellers and Kleeman 
2005, pp. 15, 16). We conclude that 2.2 mi (3.6 km) is likely near the 
upward limit of dispersal capability for the California red-legged frog 
within a single season and that a 1-mile (1.6-km) dispersal distance 
will, in most instances, provide for connectivity between breeding 
aquatic habitats, non-breeding aquatic habitats, and areas of non-
aquatic (i.e., upland) habitat and can be used as a general guide for 
habitat use. However, we also concur with Fellers and Kleeman (2007, p. 
279) in that the exact extent of habitat use by the California red-
legged frog should be determined on a site-by-site basis.
    Accessible dispersal habitat provides opportunities for the 
California red-legged frog to move freely across the landscape in 
search of adjacent breeding and non-breeding habitats. Accessible 
dispersal habitat is considered essential to the conservation of the 
subspecies and provides for: (1) Opportunities for movement and 
establishment of home ranges by juvenile recruits; (2) maintaining gene 
flow by the movement of both juveniles and adults between 
subpopulations; and (3) recruitment into breeding habitat or 
recolonization of breeding habitat after local extirpations.

Primary Constituent Elements (PCEs) for the California Red-Legged Frog

    Pursuant to our regulations, we are required to identify the 
physical and biological features within the geographical area occupied 
by the California red-legged frog at the time of listing that are 
essential to the conservation of the species and which may require 
special management considerations or protections. The physical and 
biological features are those PCEs laid out in a specific spatial 
arrangement and quantity determined to be essential to the conservation 
of the species. All areas designated as critical habitat for California 
red-legged frogs are occupied, are within the subspecies' historical 
geographic range, and contain sufficient PCEs to support at least one 
life-history function.
    Based on the above needs and our current knowledge of the life 
history, biology, and ecology of the species, and the habitat 
requirements for sustaining the essential life-history functions of the 
species, we have determined that the PCEs essential to the conservation 
of the California red-legged frog are:
    (1) Aquatic Breeding Habitat. Standing bodies of fresh water (with 
salinities less than 7.0 ppt), including: natural and manmade (e.g., 
stock) ponds, slow-moving streams or pools within streams, and other 
ephemeral or permanent water bodies that typically become inundated 
during winter rains and hold water for a minimum of 20 weeks in all but 
the driest of years.
    (2) Non-Breeding Aquatic Habitat. Freshwater and wetted riparian 
habitats, as described above, that may not hold water long enough for 
the subspecies to hatch and complete its aquatic life cycle but that do 
provide for shelter, foraging, predator avoidance, and aquatic 
dispersal for juvenile and adult California red-legged frogs. Other 
wetland habitats that would be considered to meet these elements 
include, but are not limited to: plunge pools within intermittent 
creeks; seeps; quiet water refugia during high water flows; and springs 
of sufficient flow to withstand the summer dry period.

[[Page 53498]]

    (3) Upland Habitat. Upland areas adjacent to or surrounding 
breeding and non-breeding aquatic and riparian habitat up to a distance 
of 1 mi (1.6 km) in most cases and comprised of various vegetational 
series such as grasslands, woodlands, wetland, or riparian plant 
species that provides the frog shelter, forage, and predator avoidance. 
Upland features are also essential in that they are needed to maintain 
the hydrologic, geographic, topographic, ecological, and edaphic 
features that support and surround the wetland or riparian habitat. 
These upland features contribute to the filling and drying of the 
wetland or riparian habitat and are responsible for maintaining 
suitable periods of pool inundation for larval frogs and their food 
sources, and provide breeding, non-breeding, feeding, and sheltering 
habitat for juvenile and adult frogs (e.g., shelter, shade, moisture, 
cooler temperatures, a prey base, foraging opportunities, and areas for 
predator avoidance). Upland habitat should include structural features 
such as boulders, rocks and organic debris (e.g., downed trees, logs), 
as well as small mammal burrows and moist leaf litter.
    (4) Dispersal Habitat. Accessible upland or riparian dispersal 
habitat within designated units and between occupied locations within a 
minimum of 1 mi (1.6 km) of each other and that allows for movement 
between such sites. Dispersal habitat includes various natural habitats 
and altered habitats such as agricultural fields, which do not contain 
barriers (e.g., heavily traveled road without bridges or culverts) to 
dispersal. Dispersal habitat does not include moderate- to high-density 
urban or industrial developments with large expanses of asphalt or 
concrete, nor does it include large reservoirs over 50 ac (20 ha) in 
size, or other areas that do not contain those features identified in 
PCE 1, 2, or 3 as essential to the conservation of the subspecies.
    With this proposed designation of critical habitat, we intend to 
conserve the physical and biological features that are essential to the 
conservation of the species, through the identification of the 
appropriate quantity and spatial arrangement of the PCEs sufficient to 
support the life-history functions of the species. Because not all 
life-history functions require all the PCEs, not all areas designated 
as critical habitat will contain all the PCEs.
    Each of the areas designated in this rule have been determined to 
contain sufficient PCEs to provide for one or more of the life-history 
functions of the California red-legged frog. In some cases, the PCEs 
exist as a result of ongoing Federal actions. As a result, ongoing 
Federal actions at the time of designation will be included in the 
baseline in any consultation conducted subsequent to this designation.

Special Management Considerations or Protections

    When designating critical habitat, we assess whether the occupied 
areas contain the physical and biological features that are essential 
to the conservation of the species, and whether these features may 
require special management considerations or protections.
    The area proposed for designation as revised critical habitat will 
require some level of management to address the current and future 
threats to the California red-legged frog and to maintain the physical 
and biological features essential to the conservation of the species. 
In all units, special management will be required to ensure that 
aquatic and upland habitat are able to provide abundant breeding and 
non-breeding habitat, prey habitat, shelter, and connectivity within 
the landscape. The designation of critical habitat does not imply that 
lands outside of critical habitat do not play an important role in the 
conservation of the California red-legged frog. Federal activities that 
may affect areas outside of critical habitat, such as development, 
agricultural activities, and road construction, are still subject to 
review under section 7 of the Act if they may affect the California 
red-legged frog because Federal agencies must consider both effects to 
the frog and effects to critical habitat independently. The 
prohibitions of section 9 of the Act (e.g., harm, harass, capture, 
kill) also continue to apply both inside and outside of designated 
critical habitat.
    A detailed discussion of threats to the California red-legged frog 
and its habitat can be found in the final listing rule (61 FR 25813, 
May 23, 1996), the previous critical habitat designation (66 FR 14626, 
March 13, 2001), and the final Recovery Plan (May 28, 2002, Service 
2002, pp. 1-173). Threats that may warrant special management of those 
features that define essential habitat (appropriate quantity and 
distribution of PCEs) for the California red-legged frog include, but 
are not limited to: trematode and chytrid fungus disease; direct and 
indirect impacts from some human recreational activities; flood control 
maintenance activities; water diversions; overgrazing activities; 
competition and predation by nonnative species; and habitat removal and 
alteration by urbanization.

Criteria Used To Identify Critical Habitat

    We are proposing to designate critical habitat in areas that we 
have determined were occupied by the species at the time of listing, 
and that contain the PCEs in the quantity and spatial arrangement to 
support life-history functions essential for the conservation of the 
species. We are also proposing to designate critical habitat in areas 
that were not occupied by the species at the time of listing, but were 
subsequently occupied. We have determined that these areas, which are 
currently occupied, are essential to the conservation of the species.
    As required by section 4(b)(1)(A) of the Act, we use the best 
scientific data available in determining areas that contain the 
features that are essential to the conservation of the California red-
legged frog. The material included the Recovery Plan developed for the 
California red-legged frog (Service 2002, pp. 1-173); data in reports 
submitted during section 7 consultations and by biologists holding 
section 10(a)(1)(A) recovery permits; research published in peer-
reviewed articles and presented in academic theses and agency reports; 
and regional GIS coverages. We are not proposing to designate any areas 
outside the geographical area presently occupied by the subspecies.
    In designating critical habitat for the California red-legged frog, 
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 examined the core areas identified in 
the Recovery Plan, and used these to focus our analysis of which areas 
to include as critical habitat. We attempted to include a distribution 
of critical habitat within each core area. We included some areas which 
were occupied at the time of listing as well as some areas subsequently 
identified as occupied. We found that the majority of newer occurrence 
records were within areas already known to support the California red-
legged frog. We identified critical habitat units that have the highest 
likelihood to contain populations of California red-legged frogs based 
on: (1) The presence of the defined PCEs; (2) the density of California 
red-legged frog occurrences; and (3) the kind, amount, and quality of 
habitat associated with those occurrences. The units contain the 
appropriate quantity and distribution of PCEs to support the behaviors 
or life-cycle stages we have determined are

[[Page 53499]]

essential to the conservation of the subspecies.
    After working through the criteria used to identify critical 
habitat, we then made an effort to avoid developed areas, such as 
housing and commercial developments which do not contain the PCE's for 
the California red-legged frog, and are unlikely to contribute to the 
conservation of the California red-legged frog. We also avoided 
fragmented areas such as those surrounded by development. Areas within 
the boundaries of the mapped units such as buildings, roads, parking 
lots, railroads, canals, levees, airport runways, other paved areas, 
lawns, and other urban landscaped areas are not critical habitat and 
are not included in this proposed designation. Federal actions limited 
to these areas would not trigger a section 7 consultation, unless such 
actions affect the subspecies or the PCEs in adjacent critical habitat. 
Agricultural lands may have been included if they were within areas 
identified as necessary for dispersal or connectivity between known 
occurrences. However, we avoided known areas of intensive agriculture 
that lacked the PCEs for the California red-legged frog.
    We considered several criteria in the selection of areas that 
contain the essential features for the California red-legged frog and 
focused on designating units: (1) Throughout the current geographical, 
elevational, and ecological distribution of the subspecies; (2) that 
would maintain the current population structure across the subspecies' 
range; (3) that retain or provide for connectivity between breeding 
sites that allows for the continued existence of viable and essential 
metapopulations, despite fluctuations in the status of subpopulations; 
(4) that possess large continuous blocks of occupied habitat, 
representing source populations or unique ecological characteristics; 
and (5) that contain sufficient upland habitat around each breeding 
location to allow for sufficient survival and recruitment to maintain a 
breeding population over the long term. We then compared areas meeting 
these requirements to the core areas identified in the recovery plan 
for the species (Service 2002, pp. 1-173) and adjusted the number and 
distribution of units so that all core areas were represented in the 
proposed revised designation. For more information see ``Summary of 
Changes from Previously Designated Critical Habitat'' section below.
    We first determined the occupancy status of areas on the basis of 
report data compiled by the CDFG (CNDDB 2008). We used the final 
listing rule to establish those areas occupied at the time of listing. 
All other area designations were based on occupancy data collected 
since listing. Our designation does not include all occupied areas. 
When determining which occupied areas are essential to the conservation 
of the subspecies and meet the definition of critical habitat, we 
considered theories of metapopulation persistence, on-the-ground survey 
data, and California red-legged frog longevity. Bulger et al. (2003, 
pp. 85, 92) found more than 75 percent of California red-legged frogs 
are resident at permanent aquatic habitats over the course of a year, 
thereby providing local population stability. Survey data provided to 
us during the development of the revised proposed critical habitat rule 
show an average persistence of 19 years for California red-legged frog 
populations. Additionally, California red-legged frogs are considered 
long lived with a minimum longevity of male and female California red-
legged frogs between 8 and 10 years respectively (Jennings et al. 1992, 
p. 3), which also contributes to generational and metapopulation 
stability.
    The extant occurrences within the critical habitat units comprise 
approximately 63 percent of known extant occurrences within the range 
of the subspecies. We critically evaluated records in which the exact 
site location was not precisely identified or could not be confirmed, 
and removed those locations from our analysis. We then selected areas 
that are inhabited by source populations that are capable of 
maintaining their current population levels and capable of providing 
individuals to recruit into subpopulations found in adjacent areas. We 
also selected several areas which have other unique ecological 
significance, with the goal of maintaining the full range of the 
habitat variability and evolutionary adaptation in this subspecies. 
These include areas on the periphery of the current range and elsewhere 
which represent the distribution of the subspecies, and areas that 
provide connectivity among source populations or between source 
populations.
    The critical habitat units were delineated by creating approximate 
areas for the units by screen-digitizing polygons (map units) using 
ArcMap (Environmental Systems Research Institute, Inc.), a computer GIS 
program. The polygons were created by overlaying a 1-mile (1.6-km) 
radius around locations with occurrence records. We then used this 
distance as a guide for mapping the essential features around locations 
where California red-legged frog populations are present (see Dispersal 
Habitat above). As stated above, California red-legged frogs have been 
documented to disperse from ponds and streams a distance over 2.0 mi 
(3.2 km) (Bulger et al. 2003, p. 90). However, based on a review of the 
most current literature and information gathered in development of the 
Recovery Plan for the subspecies, we have determined that the 2.0-mile 
(3.2-km) distance is toward the maximum dispersal distance for the 
subspecies during a single season, and that the 1-mile (1.6-km) 
distance is more reflective of the average dispersal distance for the 
California red-legged frog (Rathbun et al. 1993, pp. 15, 16; Wright 
1999, pp. 1, 2; Bulger et al. 2003, p. 90; Tatarian 2004, table 9; 
Fellers and Kleeman 2005, pp. 14-16; Fellers and Kleeman 2007, pp. 276-
286). Although the studies discussed above provide an approximation of 
the distances that California red-legged frogs can move from their 
aquatic habitats, breeding ponds, and other wetland habitats in search 
of suitable upland refugia or other breeding locations, we recognize 
that upland habitat features will influence California red-legged frog 
movements in a particular landscape. As a result, we made adjustments 
to the upland areas to include additional areas up to the watershed 
boundaries or to include habitat containing the PCEs beyond the 1 mi 
(1.6 km) distance where appropriate to aggregate clumps of occurrences 
and provide connectivity between occurrences. In some other instances, 
we removed areas not containing the PCEs from this revised proposed 
designation including agricultural, developed, disturbed, or fragmented 
lands. Due to the conversion of GIS data from two different geographic 
projection zones (zone 10 and zone 11) and conversion of the data to 
acres and hectares, some rounding adjustments may be reflected in the 
total acreage of the units designated as critical habitat and are shown 
in the acreage tables and unit descriptions.
    We evaluated the resulting units (delineating geographic range and 
potential suitable habitat), refined elevation and hydrologic ranges, 
and identified areas not containing the essential features (i.e., not 
containing PCEs) (see Primary Constituent Elements section). We 
excluded areas because (1) they do not contain sufficient PCEs to 
support one or more of the subspecies' life processes, or (2) they have 
low-quality PCEs because either the area is highly degraded and is 
likely not restorable or the area is small, highly fragmented, or 
isolated and may

[[Page 53500]]

provide little or no long-term conservation value.
    When determining critical habitat boundaries, we made every effort 
to avoid including developed areas such as buildings, paved areas, and 
other structures that lack PCEs for the California red-legged frog. The 
scale of the maps 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 remaining 
within critical habitat boundaries shown on the maps of this proposed 
rule are excluded by text and are not designated as critical habitat. 
Therefore, Federal actions limited to these areas would not trigger 
section 7 consultation with respect to critical habitat and the 
requirement of no adverse modification unless the specific actions may 
affect the subspecies or PCEs in adjacent critical habitat.
    We further refined the preliminary areas described above based on 
the boundaries of the watershed and stream reach, as well as on the 
extent of aquatic habitat and the upland dispersal distance. We focused 
on areas of high California red-legged frog abundance, areas needed to 
maintain connectivity between aquatic breeding habitat, and areas of 
unique ecological significance. We used the core areas identified in 
the Recovery Plan (Service 2002, pp.1-173) to assist in focusing the 
areas and extent of the critical habitat boundaries. We refined unit 
boundaries by using watershed boundaries from the State of California's 
CALWATER watershed classification system (version 2.2) using the 
smallest (planning watersheds) watershed designation. Visual inspection 
of mapped California red-legged frog occurrence records revealed un-
surveyed regions surrounded by surveyed regions, mostly in highly 
developed areas. Rather than designating critical habitat in the 
development fringe, we designated in areas where fewer surveys have 
been conducted but where California red-legged frogs are likely to 
occur based on similarity of habitat and presence of PCEs. In areas 
where planning watersheds were large or had been significantly altered 
hydrologically, we used alternative structural, political, or 
topographic boundaries (e.g., roads, county boundaries, ridgeline 
features, elevation contour lines) based on habitat characteristics as 
critical habitat boundaries because, in these areas, the benefits of 
using planning watersheds were limited in that they included areas 
outside the subspecies' dispersal distance or were of unknown 
conservation value for the California red-legged frog. We made every 
attempt to connect localized California red-legged frog populations 
into single critical habitat units if sufficient PCEs were present to 
do so.
    Section 10(a)(1)(B) of the Act authorizes us to issue permits for 
the take of listed species incidental to otherwise lawful activities. 
An incidental take permit application must be supported by an HCP that 
identifies conservation measures that the permittee agrees to implement 
for the species to minimize and mitigate the impacts of the requested 
incidental take. We may 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 should a determination be made that the 
benefits of exclusion outweigh the benefits of inclusion as discussed 
in section 4(b)(2) of the Act. We propose to exclude lands covered by 
the Bonny Doon HCP, the East Contra Costa HCP, and the Western 
Riverside Multiple Species HCP (see section Relationship of Critical 
Habitat to Habitat Conservation Plan Lands--Exclusions Under Section 
4(b)(2) of the Act below).
    We propose to design