Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Peninsular Bighorn Sheep and Determination of a Distinct Population Segment of Desert Bighorn Sheep (Ovis canadensis nelsoni, 17288-17365 [E9-7767]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 74, Number 70 (Tuesday, April 14, 2009)]
[Rules and Regulations]
[Pages 17288-17365]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E9-7767]



[[Page 17287]]

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Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Designation of Critical 
Habitat for Peninsular Bighorn Sheep and Determination of a Distinct 
Population Segment of Desert Bighorn Sheep (Ovis canadensis nelsoni); 
Final Rule

Federal Register / Vol. 74, No. 70 / Tuesday, April 14, 2009 / Rules 
and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

FWS-R8-ES-2007-0005; 92210-1117-0000-B4
RIN 1018-AV09


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for Peninsular Bighorn Sheep and Determination of a 
Distinct Population Segment of Desert Bighorn Sheep (Ovis canadensis 
nelsoni)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), designate 
revised critical habitat for the Peninsular bighorn sheep, a distinct 
population segment (DPS) of desert bighorn sheep (Ovis canadensis 
nelsoni) occupying the Peninsular Ranges of Southern California, under 
the Endangered Species Act of 1973, as amended (Act). In total, 
approximately 376,938 acres (ac) (152,542 hectares (ha)) fall within 
the boundaries of the critical habitat designation. This revised 
designation of critical habitat for Peninsular bighorn sheep reduces 
the 2001 designation by approximately 467,959 ac (189,377 ha). The 
revised critical habitat is located in Riverside, San Diego, and 
Imperial Counties, California.

DATES: This rule becomes effective on May 14, 2009.

ADDRESSES: The final rule, final economic analysis, and map of critical 
habitat will be available on the Internet at https://www.regulations.gov. Supporting documentation we used in preparing this 
final rule will be available for public inspection, by appointment, 
during normal business hours, at the U.S. Fish and Wildlife Service, 
Carlsbad Fish and Wildlife Office, 6010 Hidden Valley Road, Suite 
101, Carlsbad, CA 92011; telephone 760-431-9440; facsimile 
760-431-5901.

FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, U.S. 
Fish and Wildlife Service, Carlsbad Fish and Wildlife Office (see 
ADDRESSES section). If you use a telecommunications device for the deaf 
(TDD), call the Federal Information Relay Service (FIRS) at 800-877-
8339.

SUPPLEMENTARY INFORMATION:

Background

    It is our intent to discuss only those topics directly relevant to 
the designation of critical habitat for Peninsular bighorn sheep in 
this final rule. For more information on the taxonomy, biology, and 
ecology of Peninsular bighorn sheep, refer to the final listing rule 
published in the Federal Register on March 18, 1998 (63 FR 13134), the 
original final critical habitat rule published in the Federal Register 
on February 1, 2001 (66 FR 8650), the proposed rule to revise critical 
habitat published in the Federal Register on October 10, 2007 (72 FR 
57740), and the August 26, 2008 (73 FR 50498), notice of availability 
of the draft economic analysis (DEA) that announced revisions to the 
proposed critical habitat designation.
    The listed entity treated in this rule is a DPS of desert bighorn 
sheep (Ovis canadensis nelsoni). We will refer to this entity as 
Peninsular bighorn sheep, or as a DPS (not species or subspecies).
    As stated in the October 10, 2007, proposed critical habitat rule, 
we are formally recognizing the listed entity as Peninsular bighorn 
sheep, a DPS of the desert bighorn sheep (Ovis canadensis nelsoni). 
This is the currently accepted taxonomic placement of these animals. We 
submitted this as a change for inclusion in the Code of Federal 
Regulations (CFR). The taxonomic revision does not affect discreteness 
and significance of Peninsular bighorn sheep as a DPS. In the 1998 
final listing rule, Peninsular bighorn sheep were listed as a DPS of 
the species Ovis canadensis. At the time of listing at least six 
subspecies of bighorn sheep (Ovis canadensis) were named, including 
Ovis canadensis cremnobates, which is a name that previously had been 
applied to the Peninsular bighorn sheep. However, because of ongoing 
questions regarding the distinctiveness of the subspecific taxa at that 
time, the Peninsular Ranges population was considered a distinct 
population segment (DPS) of the species O. canadensis rather than as a 
subspecies or a DPS of a particular subspecies.
    Relevant information regarding the systematic relationships of the 
infraspecific (below species rank) taxa of bighorn sheep at or near the 
time of listing was based on morphometric (variation in size and shape) 
assessments, as well as molecular analyses, such as mitochondrial DNA 
(mtDNA) assessments (Wehausen and Ramey 1993; Ramey 1993; Ramey 1995; 
Boyce et al. 1999) and microsatellite and histocompatibility complex 
loci analysis (Boyce et al. 1997; Gutierrez-Espeleta et al. 1998). 
While the discriminatory value of these various approaches was not 
addressed in the recovery plan (USFWS 2000), the Service concluded in 
the morphology and taxonomy section of the Recovery Plan (USFWS 2000, 
p. 3) that the currently recognized subspecies for desert bighorn 
sheep, Ovis canadensis nelsoni, includes the Peninsular bighorn sheep. 
This taxonomic placement was recognized in the final critical habitat 
designation for the Peninsular bighorn sheep published in 2001 (USFWS 
2001, p. 8650). In that rule, we described the range of the DPS as 
coincident with the U.S. portion of the formerly recognized Ovis 
canadensis cremnobates. The current known range for the Peninsular 
bighorn sheep remains the same, as does its status as a DPS of the 
desert bighorn sheep (Ovis canadensis nelsoni).
    Regardless of its systematic affiliation, the Peninsular bighorn 
sheep continues to meet the criteria for consideration as a DPS. Within 
this document, we refer to the listed entity as a distinct population 
segment (DPS) of desert bighorn sheep (Ovis canadensis nelsoni), not as 
a subspecies as we did within the discussion portion of the October 10, 
2007, proposed critical habitat rule. We will continue to use the 
common name Peninsular bighorn sheep when referring to this DPS. No 
discussions or references to the Peninsular bighorn sheep DPS are 
intended to apply to any other portions of the range (e.g., San 
Bernardino Mountains, Joshua Tree National Park, the desert mountains 
of southwestern Nevada and northwestern Arizona) of the desert bighorn 
sheep (Ovis canadensis nelsoni). For a detailed discussion of the DPS 
analysis for Peninsular bighorn sheep, see the Distinct Vertebrate 
Population Segment section of the 1998 final listing rule (March 18, 
1998, 63 FR 13134). Therefore, we are changing the listed entity from a 
DPS of the species Ovis canadensis, to a DPS of the subspecies Ovis 
canadensis nelsoni. This final rule includes a change to the List of 
Endangered and Threatened Wildlife at 50 CFR 17.11(h) to reflect this 
change.

DPS Description, Life History, Distribution, Ecology, and Habitat

    No new substantial information pertaining to the DPS description, 
life history, ecology, or habitat of Peninsular bighorn sheep was 
received following the 2007 proposed rule to revise critical habitat 
for this DPS. Therefore, please refer to the final listing rule 
published in the Federal Register on March 18, 1998 (63 FR 13134), and 
the proposed rule to revise critical habitat published in the Federal 
Register on October 10, 2007 (72 FR 57740), for a discussion of the 
DPS's description, life history, ecology, and habitat.

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DPS Distribution

    During the first public comment period for the proposed rule, we 
received new information regarding occurrence data that had been 
collected within the past year. The areas in which new sheep occurrence 
data was received include the South Santa Rosa Mountains along Grave 
Wash and the Jacumba Mountains near Interstate 8. The occurrence data 
received falls within the boundary of the 2001 critical habitat 
designation and the 2000 Recovery Plan area; therefore, we do not 
believe this new information markedly affects the known distribution of 
Peninsular bighorn sheep. However, we considered this new occurrence 
data and revised our proposed designation to include these areas 
recently used by Peninsular bighorn sheep (see the Notice of 
Availability (NOA), August 26, 2008, 73 FR 50498). The areas 
represented by the new occurrence data are included in this final 
designation (see the ``Summary of Changes From the 2007 Proposed Rule 
To Revise Critical Habitat to This Final Rule to Revise Critical 
Habitat'' section of this final rule).

Previous Federal Actions

    As discussed in the proposed rule to revise critical habitat for 
this DPS, a July 31, 2006, court-approved consent decree enacted a 
limited partial vacatur of tribal, mining, and Desert Riders lands and 
remanded the critical habitat designation back to the Service for new 
rulemaking. The Service was obligated under the consent decree to 
submit a proposed revised critical habitat designation to the Federal 
Register on or before September 30, 2007, and a final revised critical 
habitat designation on or before September 30, 2008. We published a 
proposed revised critical habitat designation in the Federal Register 
on October 10, 2007 (72 FR 57740), and accepted public comments on the 
proposed revised designation for 60 days, ending December 10, 2007. 
Because significant new information was received, the parties agreed to 
extend the due date to the Federal Register of the final revised 
critical habitat rule to March 30, 2009. On August 26, 2008 (73 FR 
50498), we opened a second public comment period on the proposed 
revised critical habitat designation and announced our intention to 
hold two public hearings on the proposed rule that were held in Palm 
Desert, California, on September 10, 2008. In the same Federal Register 
notice we announced the availability of our Draft Economic Analysis 
(DEA) (dated June 9, 2008) and announced changes to the proposed rule. 
We accepted public comments during the second open comment period for 
60 days, ending October 27, 2008. For more information on previous 
Federal actions concerning Peninsular bighorn sheep, refer to the final 
listing rule published in the Federal Register on March 18, 1998 (63 FR 
13134), the final critical habitat designation published in the Federal 
Register on February 1, 2001 (66 FR 8650), and the proposed rule to 
revise critical habitat published in the Federal Register on October 
10, 2007 (72 FR 57740).

Summary of Comments and Recommendations

    We requested written comments from the public during two comment 
periods on the proposed rule to revise critical habitat for Peninsular 
bighorn sheep. The first comment period opened October 10, 2007 (72 FR 
57740), and closed December 10, 2007, and was associated with the 
publication of the proposed rule. We received several requests for a 
public hearing during this comment period. The second comment period 
opened August 26, 2008 (73 FR 50498), and closed October 27, 2008, and 
was associated with the notice of availability of the DEA, announcement 
of revisions to the proposed critical habitat, and a notice of public 
hearings that were held September 10, 2008. During these two public 
comment periods, we contacted appropriate Federal, State, and local 
agencies; scientific organizations; and other interested parties and 
invited them to comment on the proposed rule to revise critical habitat 
for this DPS and the associated DEA.
    During the first comment period, we received 212 public comments 
directly addressing the proposed revision of critical habitat: 1 from a 
Federal agency, 2 from State agencies, 1 from an elected official, and 
208 from organizations and individuals. During the second comment 
period and the September 10, 2008, public hearings, we received 5,092 
comments directly addressing the proposed revision of critical habitat 
for this DPS or the DEA: 1 from an elected official, 2 from State 
agencies, 3 from local governments, and 5,086 from organizations and 
individuals.

Peer Review

    In accordance with our policy on peer review published in the 
Federal Register on July 1, 1994 (59 FR 34270), we solicited expert 
opinions from five knowledgeable individuals with scientific expertise 
that included familiarity with the DPS, the geographic region in which 
it occurs, and conservation biology principles. We received responses 
from all five of the peer reviewers.
    We reviewed all comments received from the peer reviewers and the 
public for substantive issues and new information regarding critical 
habitat for Peninsular bighorn sheep. These comments are addressed 
below and incorporated into the final rule as appropriate.

Peer Reviewer Comments

    Comment 1: Several peer reviewers stated the proposed critical 
habitat is flawed because it does not provide for connectivity. One 
peer reviewer stated further that the proposal fragments the habitat 
available to the Peninsular bighorn sheep. Several peer reviewers 
asserted that, although essential habitat (as identified by the 
Peninsular bighorn sheep Recovery Team and depicted in the 2000 
Peninsular bighorn sheep Recovery Plan) and critical habitat originally 
designated in 2001 promoted habitat connectivity among all 
subpopulations, the proposed critical habitat essentially severs the 
San Jacinto Mountains subpopulation (Unit 1) and the Carrizo Canyon 
subpopulation (Unit 3) from the remainder of the range (Units 2A and 
2B). One peer reviewer also noted that movement of Peninsular bighorn 
sheep has been documented between these areas. According to the same 
peer reviewer, a collared ram from the San Jacinto Mountains was 
observed during July and August 2008 on several different occasions in 
the northern Santa Rosa Mountains with other bighorn sheep there. The 
peer reviewer concluded that not including these areas as critical 
habitat incorrectly suggests that these areas are not critical to the 
long-term recovery or survival of the population.
    Another peer reviewer stated that movement between Units l, 2A, 2B, 
and 3 is important and that critical habitat should be extended to 
protect corridors connecting the units. The same peer reviewer 
maintained that if any unit is isolated, the subpopulation may not be 
viable and that critical habitat should be expanded to include 
corridors for movement between units. One peer reviewer noted an 
extensive and irrefutable body of scientific literature that 
illustrates the importance of habitat connectivity. Two peer reviewers 
stated that, despite the acknowledgement in the proposed rule that 
connectivity is vital for this species' recovery, the revised critical 
habitat designation decreases connectivity or does not include 
corridors for movement. One peer reviewer asserted that habitat 
fragmentation will only promote the

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decline of this DPS and goes directly against the recommendations of 
the Recovery Plan that the Service adopted.
    Our Response: We agree with the peer reviewers that habitat 
connectivity is important to allow for movement between ewe groups and 
to maintain genetic variation. We also agree with the peer reviewer 
that an extensive amount of scientific evidence illustrates the 
importance of habitat connectivity, and we considered this information 
during the development of this critical habitat designation. We 
acknowledge that areas potentially providing connectivity between Units 
1 and 2A and between Units 2B and 3 were included in the 2001 critical 
habitat designation; however, based on our reevaluation of the data 
available at the time of the 2001 designation, data obtained since, and 
our revised methodology for delineating critical habitat, we find that 
those areas do not meet the definition of critical habitat because the 
available data do not identify specific areas between these units that 
contain the physical or biological features essential to the 
conservation of the DPS.
    The best available data do not provide any information indicating 
what areas, if any, Peninsular bighorn sheep use as connectivity 
corridors within the expansive areas between Units 1 and 2A and Units 
2B and 3. Although the peer reviewers presented data showing that at 
least one collared ram has moved between Units 1 and 2A, we do not have 
occurrence data suggesting a specific corridor between these units. In 
addition, we have no data documenting natural sheep movement between 
Units 3 and 2B. As such we have not included specific corridors between 
Units 1 and 2A or between Units 3 and 2B in the designation. However, 
we will continue to monitor movement between these units to determine 
if specific movement corridors exist. In contrast, where the available 
data do support the identification of specific areas utilized by the 
DPS as movement corridors, such as between the ewe groups in the Santa 
Rosa Mountains and the Vallecito Mountains ewe group, those areas are 
included in the critical habitat designation.
    We recognize this finding is different than what is outlined as 
essential habitat in the 2000 Recovery Plan and what was designated as 
critical habitat in the 2001 designation (which largely adopted the 
boundary delineated in the Recovery Plan). The Recovery Plan and 2001 
critical habitat rule note that allowing for ram movement between ewe 
groups is important for maintaining genetic variation in the Peninsular 
bighorn sheep metapopulation. While we believe connectivity areas are 
important for the Peninsular bighorn sheep's recovery, we have 
significantly more data available today than when the Recovery Plan and 
2001 critical habitat were finalized. We have utilized the currently 
available data to more precisely identify areas meeting the definition 
of critical habitat; in particular, areas related to connectivity. Such 
areas are included in this designation where the data support the 
determination that such areas contain the physical and biological 
features essential to the conservation of the DPS. For other potential 
connectivity areas that were included in the 2001 designation, the 
available movement and occurrence data we have for those areas do not 
support the identification of specific areas that provide a movement 
corridor that is essential for the conservation of the DPS.
    We believe it is important to note that critical habitat 
designation is a different process than development of a recovery plan. 
A critical habitat designation is a specific regulatory action that 
defines specific areas as critical habitat in accordance with the 
statutory definition. A recovery plan is a guidance document developed 
in cooperation with partners, which provides a roadmap with detailed 
site-specific management actions to help conserve listed species and 
their ecosystems. The term ``essential,'' as used in the recovery plan, 
is not necessarily used in the same manner as it is used in the 
definition of critical habitat. The recovery plan provides important 
information about the species and the actions that are needed to bring 
about its recovery, while critical habitat identifies specific areas 
that are essential for the species' conservation.
    The deviation from the Peninsular bighorn sheep Recovery Plan 
boundary and the 2001 final critical habitat designation is primarily 
the result of using a revised methodology to delineate critical 
habitat. Our revised methodology incorporates new information to best 
identify areas that meet the definition of critical habitat (see 
``Summary of Changes From the 2001 Critical Habitat Designation To the 
2007 Proposed Rule To Revise Critical Habitat'' section for more 
discussion). As a result, the final revised critical habitat boundary 
does not include areas the Recovery Plan identified as necessary for 
the conservation of the Peninsular bighorn sheep that we since 
determined (based on the best available data at this time) are not 
essential for the conservation of this DPS. Therefore, we believe the 
final revised critical habitat boundary more precisely maps the 
physical and biological features that occur within the geographical 
area occupied by the Peninsular bighorn sheep at the time of listing, 
which includes those areas containing preferred habitat for sheep use.
    There are likely additional areas outside of the final revised 
critical habitat boundary that contain some of the PCEs, including 
areas identified in the Recovery Plan and 2001 critical habitat. We 
recognize that areas outside of the critical habitat boundary are 
likely utilized by Peninsular bighorn sheep (primarily for movement of 
rams between ewe groups). However, as stated above, the data available 
at this time do not support the identification of specific areas 
containing the essential features that provide a movement corridor 
between Units 1 and 2A or between Units 2B and 3. Additionally, Unit 2A 
is continuous with Unit 2B and these units contain a large contiguous 
portion of the Peninsular Ranges allowing for movement between six ewe 
groups with these units. Furthermore, although we do not have 
information to identify specific movement corridors, the areas between 
Units 1 and 2A or between Units 2B and are steep, rugged, and remote 
and there are no perceived threats in these areas. Therefore, we are 
confident that these areas will still be available for any natural 
sheep movements between units allowing for genetic connectivity.
    We recognize that the designation of critical habitat may not 
include all of the habitat that may eventually be determined to be 
necessary for the recovery of Peninsular bighorn sheep, and critical 
habitat designations do not signal that habitat outside the designation 
is unimportant or may not contribute to recovery. Areas outside the 
final revised critical habitat designation will continue to be subject 
to conservation actions implemented under section 7(a)(1) of the Act 
and regulatory protections afforded by the section 7(a)(2) jeopardy 
standard and the prohibitions of section 9 of the Act if actions 
occurring in these areas may affect sheep; these protections and 
conservation tools will continue to contribute to recovery of the DPS.
    Please see the ``Criteria Used To Identify Critical Habitat'' and 
``Summary of Changes From the 2001 Critical Habitat Designation To the 
2007 Proposed Rule To Revise Critical Habitat'' sections of this final 
rule for further discussion of this topic.
    Comment 2: Two peer reviewers stated that exclusion of areas under 
the Agua Caliente Band of Cahuilla Indians Tribal Habitat Conservation 
Plan (Tribal HCP) and Coachella Valley Multiple

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Species Habitat Conservation Plan (Coachella Valley MSHCP) is 
inappropriate because the Coachella Valley MSHCP and the Tribal HCP are 
not yet approved, and therefore provide absolutely no protection to 
Peninsular bighorn sheep or their habitat at this time. One peer 
reviewer stated it would be pre-decisional to exclude critical habitat 
based on these plans. Another peer reviewer suggested that managers and 
those making policy decisions should have solid documentation that the 
Peninsular bighorn sheep will receive the same level of enforceable 
protection from the Tribal HCP and the Coachella Valley MSHCP as 
provided by the Endangered Species Act. One peer reviewer stated that 
the proposed exclusion of tribal lands and lands covered by the 
Coachella Valley MSHCP are not supported by the best available science 
and that removal of these areas from critical habitat will increase the 
threats to the persistence and recovery of Peninsular bighorn sheep.
    Our Response: We believe the exclusion of the identified tribal 
lands and the lands covered by the Coachella Valley MSHCP, which is now 
final, is appropriate based on the potential impacts associated with 
designating these areas as critical habitat. Section 4(b)(2) of the Act 
states that the ``Secretary shall designate critical habitat, and make 
revisions thereto, on the basis of the best scientific data available 
and after taking into consideration the economic impact, the impact on 
national security, and any other relevant impact, of specifying any 
particular area as critical habitat.'' The Act further states that the 
Secretary may exclude any area from critical habitat if he determines 
that the benefits of such exclusion outweigh the benefits of specifying 
such area as part of the critical habitat, unless he determines, based 
on the best scientific and commercial data available, that the failure 
to designate such area as critical habitat will result in the 
extinction of the species concerned.
    We believe that critical habitat designation would negatively 
impact the working relationships and conservation partnerships we have 
formed with permittees, the Tribe, and other private landowners (i.e., 
other relevant impacts), and could result in decreased voluntary 
conservation efforts to benefit the Peninsular bighorn sheep. 
Additionally, as explained in detail in the ``Application of Section 
4(b)(2)--Other Relevant Impacts--Conservation Partnerships'' section of 
this final rule, we believe these conservation partnerships will 
provide as much or more benefit than consultation under section 7(a)(2) 
related to the critical habitat designation (the primary benefit of a 
designation).
    The exclusion of Agua Caliente Band of Cahuilla Indians lands is 
not based on the 2007 draft Tribal HCP, but is primarily based on the 
importance of our government-to-government relationship with the Agua 
Caliente Band of Cahuilla Indians, our conservation partnership with 
the Tribe, and their current management of tribal lands as described in 
the 2001 Tribal Conservation Strategy (adopted by the Tribe on November 
12, 2002, and implemented since its adoption). Furthermore, in 
accordance with the Secretarial Order 3206, ``American Indian Tribal 
Rights, Federal-Tribal Trust Responsibilities, and the Endangered 
Species Act'' (June 5, 1997); the President's memorandum of April 29, 
1994, ``Government-to-Government Relations with Native American Tribal 
Governments'' (59 FR 22951); Executive Order 13175; and the relevant 
provision of the Departmental Manual of the Department of the Interior 
(512 DM 2), we believe that fish, wildlife, and other natural resources 
on tribal lands are better managed under tribal authorities, policies, 
and programs than through Federal regulation wherever possible and 
practicable. Based on this philosophy, we believe that, in most cases, 
designation of tribal lands as critical habitat provides very little 
additional benefit to threatened and endangered species. Conversely, 
such designation is often viewed by tribes as unwarranted and an 
unwanted intrusion into tribal self governance, thus compromising the 
government-to-government relationship essential to achieving our mutual 
goal of managing for healthy ecosystems upon which the viability of 
threatened and endangered species populations depend. As an indication 
of the success of our partnership with the Agua Caliente Band of 
Cahuilla Indians and their commitment to natural resources management, 
a regional HCP is being developed, which incorporates protections and 
management of this DPS's essential physical and biological features.
    The protections provided by the Coachella Valley MSHCP and the 
Tribe's resource management are consistent with the mandates under 
section 7 of the Act to avoid destruction or adverse modification of 
critical habitat and go beyond that prohibition by including active 
management and protection of essential habitat areas. These established 
partnerships demonstrate a continued commitment to conservation and aid 
in fostering additional partnerships for the benefit of all sensitive 
species on tribally-owned or controlled lands, Coachella Valley MSHCP 
permittee-owned/controlled lands, and other private lands. Finally, we 
determined that the Tribe's management of its resources provides 
protection and management, in perpetuity, of lands that meet the 
definition of critical habitat for Peninsular bighorn sheep in Units 1 
and 2A, and the Coachella Valley MSHCP provides further evidence of 
this partnership and continued protection of these features. 
Furthermore, we determined that the routine implementation of 
conservation measures in these units, combined with protections 
provided under the jeopardy standard of section 7 of the Act in these 
two occupied units, provide assurances that the DPS will not go extinct 
as a result of these exclusions.
    Please see the ``Application of Section 4(b)(2)--Other Relevant 
Impacts--Conservation Partnerships'' section of this final rule for 
additional discussion of the Coachella Valley MSHCP and tribal 
conservation strategies and the benefits provided to Peninsular bighorn 
sheep.
    Comment 3: Several peer reviewers stated that alluvial fans and 
low-elevation habitat provide important resources for Peninsular 
bighorn sheep and noted that the proposed critical habitat does not 
include extensive areas of alluvial fans and other low-elevation 
habitat that were included in the 2001 critical habitat designation. 
Two peer reviewers stated that, based on a geographic information 
systems (GIS) evaluation of proposed critical habitat by California 
Department of Parks and Recreation staff, nearly 250,000 ac (101,172 
ha) of habitat have been removed from the eastern side of critical 
habitat, as compared to critical habitat designated in 2001. The peer 
reviewers further stated this area includes alluvial fans, washes, 
bajadas (i.e., converging alluvial fans), canyon bottoms, and open 
playas, which provide important forage resources and which are used 
during movement between more mountainous terrain. One peer reviewer 
stated that the fact that bighorn sheep use gentle terrain, such as 
alluvial fans and washes, despite potentially increasing their risk of 
predation, provides strong evidence that these areas provide critically 
important resources.
    Another peer reviewer commented that the 2007 proposed revision 
eliminates key low-slope areas and raises the boundary upslope, which 
they assert is a contradiction to the best available science. One peer 
reviewer noted there are contradictions of slope

[[Page 17292]]

condition in the rule based on straight lines drawn on the critical 
habitat maps, even though the text in the proposed rule describes the 
importance of gentle slopes to bighorn sheep.
    Our Response: We agree that low-elevation habitat is important for 
Peninsular bighorn sheep because these areas can provide seasonal 
abundance of forage vegetation and water resources. In our August 26, 
2008, NOA (73 FR 50498), we announced a revision to our criteria used 
to identify critical habitat to include occurrence data from 1988 to 
2008. Because of comments received from peer reviewers and the public 
about low-elevation habitat and the revision of our criteria used to 
identify critical habitat to include a larger occurrence data set, we 
reevaluated and revised our proposed revised critical habitat boundary. 
In our August 26, 2008, NOA (73 FR 50498), we announced changes to the 
proposed critical habitat revision, including the addition of 36,240 ac 
(14,667 ha) of habitat for Peninsular bighorn sheep, the majority of 
which is low-elevation, low-slope, or alluvial-fan habitat on the 
eastern edge of the Peninsular Ranges. We acknowledge there are some 
low-elevation areas included in the 2001 designation of critical 
habitat that are not included in this final designation. However, 
currently available data do not support a determination that these 
areas outside the geographical area occupied by the species at the time 
of listing are essential for the conservation of the sheep; therefore 
these areas do not meet the definition of critical habitat.
    Please see the ``Criteria Used To Identify Critical Habitat,'' the 
``Summary of Changes From the 2001 Critical Habitat Designation to the 
2007 Proposed Rule To Revise Critical Habitat,'' and the ``Summary of 
Changes From the 2007 Proposed Rule To Revise Critical Habitat to This 
Final Rule To Revise Critical Habitat'' sections of this final rule for 
further discussion of this topic.
    Comment 4: One peer reviewer objected to the statement in the 
proposed critical habitat rule that essential habitat delineated in the 
Recovery Plan (and in the 2001 critical habitat designation) included a 
``buffer'' of 0.5 mile (mi) (0.8 kilometer (km)) around slopes greater 
than or equal to 20 percent. The peer reviewer stated that buffer areas 
identified in the Recovery Plan were added as ``essential habitat'' (as 
defined in the Recovery Plan) because these areas include important 
resources for bighorn sheep; they were not added as a buffer around 
essential habitat. The peer reviewer reiterated what was written in the 
Recovery Plan (i.e., that bighorn sheep have been observed at great 
distances from slopes of greater than or equal to 20 percent, and the 
recovery team chose to define essential habitat as those areas within 
800 m (2,625 ft) of slopes of greater than or equal to 20 percent). 
Additionally, the peer reviewer stated that the Peninsular bighorn 
sheep recovery team recognized that this area would capture the 
majority of Peninsular bighorn sheep use in these areas and that 
inclusion of these areas represented inclusion of important resources.
    Our Response: The Recovery Plan acknowledges that the 800-m (2,625-
ft) area around slopes greater than or equal to 20 percent is a buffer. 
Page 157 of the Recovery Plan describes the process of delineating 
these areas as follows: ``A buffer of 0.8 kilometer (0.5 mile) was then 
applied to the perimeter of all areas of slope [greater than or equal 
to 20 percent] in the derivative grid.'' The inclusion of this area 
around 20 percent slopes adds expanses of land to the Recovery Plan 
area and the 2001 critical habitat designation, but we have relatively 
little to no occurrence data indicating that sheep use those areas. By 
including these 0.5-mi (0.8-km) buffers in the Recovery Plan, a 
boundary was developed that included almost any location that a 
Peninsular bighorn sheep could possibly roam, but such a buffer would 
not meet the statutory definition of ``critical habitat,'' because such 
areas are not essential for the conservation of the DPS. As stated in 
section 3(5)(C) of the Act, except in those circumstances determined by 
the Secretary, critical habitat shall not include the entire 
geographical area which can be occupied by the threatened or endangered 
species. Please see the ``Criteria Used To Identify Critical Habitat,'' 
and the ``Summary of Changes From the 2001 Critical Habitat Designation 
To the 2007 Proposed Rule To Revise Critical Habitat'' sections of this 
final rule for further discussion of this topic.
    Comment 5: One peer reviewer stated that the proposed delineation 
does not appear to be based on good science or conservation principles 
and that the major reduction in area (as compared to the original 
critical habitat delineated in 2001) will jeopardize the chances of 
recovery and survival of this population. A second peer reviewer stated 
that the proposal to remove over 50 percent of critical habitat is 
contrary to the PCEs as well as the Recovery Plan. A third peer 
reviewer believes the revised critical habitat is geared towards 
sustaining the current, low population level of Peninsular bighorn 
sheep, rather than planning for recovery. Finally, a fourth peer 
reviewer stated it is unclear what changed between the time of the 2000 
Recovery Plan and today that would cause certain areas to be eliminated 
that were previously determined as essential for the DPS's recovery.
    Our Response: The designation of critical habitat for Peninsular 
bighorn sheep is based on the best scientific data available regarding 
the DPS, including: (1) A compilation of data from peer-reviewed, 
published literature; (2) unpublished or non-peer reviewed survey and 
research reports; and (3) opinions of biologists knowledgeable about 
Peninsular bighorn sheep and their habitat. Consequently, the PCEs, as 
described in this final rule, represent our best assessment of what 
habitat components are essential for the conservation of Peninsular 
bighorn sheep, and we believe that our final revised designation is 
adequate to ensure the conservation of this DPS throughout its extant 
range.
    The Act defines critical habitat as (1) the specific areas within 
the geographical area occupied by the species at the time it is listed 
on which are found those physical or biological features (a) essential 
to the conservation of the species, and (b) which may require special 
management considerations or protection, and (2) specific areas outside 
the geographical area occupied by the species at the time it is listed 
upon a determination by the Secretary that such areas are essential for 
the conservation of the species. Consistent with section 3(5)(C) of the 
Act, the designation does not include the entire geographical area 
which can be occupied by Peninsular bighorn sheep, but is limited to 
those areas that we determined meet the definition of critical habitat. 
The reduction in total area from what was identified as important for 
the Peninsular bighorn sheep in the Recovery Plan and designated in 
2001 is primarily the result of: (1) Exclusions of habitat under 
section 4(b)(2) of the Act; (2) revision of the primary constituent 
elements; (3) revision of our criteria used to identify critical 
habitat; (4) removal of lands within the geographical area occupied by 
the DPS at the time it was listed that do not contain the physical or 
biological features as identified by the PCEs in the appropriate 
quantity and spatial arrangement essential to the conservation of the 
DPS; and (5) removal of lands outside the geographical area occupied by 
the DPS at the time it was listed that are not

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essential for the conservation of the DPS.
    The 2001 critical habitat designation was predominantly based on 
the 2000 Recovery Plan, and we used the best available scientific 
information at that time to delineate critical habitat. Since 2001, we 
received significant additional occurrence data and formulated a better 
understanding about specific habitat requirements of this DPS that was 
not known when we first designated critical habitat for the Peninsular 
bighorn sheep. We utilized this new information to appropriately revise 
the PCEs and criteria used to identify critical habitat, consistent 
with the Act. Additionally, case law has developed since 2001 regarding 
the Act's requirements and the definition of critical habitat (e.g., 
The Cape Hatteras Access Preservation Alliance v. U.S. Dep't of the 
Interior, 344 F. Supp. 2d 108 (D.D.C. 2004); Home Builders Ass'n of N. 
Cal. v. U.S. Fish and Wildlife Service, U.S. Dist. LEXIS 80255 (E.D. 
Cal. 2006); and Arizona Cattle Growers' Ass'n v. Kempthorne, 534 F. 
Supp. 2d 1013 (D. Ariz. 2008)).
    Therefore, we refined our approach to this critical habitat 
designation, including identification of the geographical areas 
occupied by the DPS at the time of listing, identification of physical 
or biological features essential to the conservation of the DPS, 
determination of any areas outside the geographical area occupied by 
the DPS at the time of listing that are essential for the conservation 
of the DPS, and appropriate exclusions under section 4(b)(2) of the 
Act. A complete discussion of how data collected since the 2001 
designation were utilized to refine the proposed designation can be 
found in the ``Summary of Changes From the 2001 Critical Habitat 
Designation To the 2007 Proposed Rule To Revise Critical Habitat'' and 
``Summary of Changes From the 2007 Proposed Rule To Revise Critical 
Habitat To This Final Rule To Revise Critical Habitat'' sections of 
this final rule.
    We delineated critical habitat for the Peninsular bighorn sheep 
using the criteria presented in the ``Criteria Used To Identify 
Critical Habitat'' section of this final rule. Application of these 
criteria results in the determination of the physical and biological 
features that are essential to the conservation of this DPS, identified 
as the DPS's PCEs laid out in the appropriate quantity and spatial 
arrangement essential to the conservation of the DPS. Therefore, not 
all areas supporting the identified PCEs will meet the definition of 
critical habitat.
    Refer to our response to Comment 1 for a discussion on the 
difference between critical habitat designation and development of a 
Recovery Plan.
    Our proposed designation, in combination with our August 26, 2008, 
NOA, which announced the addition of areas to the proposed designation, 
and this final designation accurately describe all specific areas 
meeting the statutory definition of critical habitat for Peninsular 
bighorn sheep. See the ``Summary of Changes From the 2001 Critical 
Habitat Designation To the 2007 Proposed Rule To Revise Critical 
Habitat'' and ``Summary of Changes From the 2007 Proposed Rule To 
Revise Critical Habitat To This Final Rule To Revise Critical Habitat'' 
sections of this final rule for more information.
    Comment 6: Two peer reviewers pointed out that the proposed 
critical habitat rule states that researchers have documented movement 
of rams ``between up to three ewe groups.'' The peer reviewers 
suggested this statement incorrectly cites Rubin et al. (1998), which 
documented male movement among at least six groups, and the proposed 
rule therefore underestimates the importance of connectivity throughout 
the range. The peer reviewers stated that researchers have documented 
movement of radio collared males and females among all eight 
subpopulations, demonstrating that these subpopulations are currently 
linked via animal movement. One peer reviewer stated that historic ram 
movement data between the northern Santa Rosa Mountains and the San 
Jacinto Mountains was not used in delineating proposed critical 
habitat. The peer reviewer further stated that they believe the Service 
has had this data for years and, if used, they believe the Service 
would not have developed a critical habitat designation lacking 
connectivity between critical habitat units.
    Our Response: We corrected the section of the critical habitat 
designation involving the Rubin et al. (1998) citation mentioned above 
and included the additional information on the metapopulation structure 
of Peninsular bighorn sheep into the PCEs discussion in this rule. With 
regard to historic ram movement data and connectivity, see our response 
to Comment 1 and the ``Criteria Used To Identify Critical Habitat'' and 
``Summary of Changes From the 2001 Critical Habitat Designation To the 
2007 Proposed Rule To Revise Critical Habitat'' sections of this final 
rule for further discussion.
    Comment 7: One peer reviewer believes that the critical habitat 
designation should encompass areas of historical occupancy if it is 
intended to aid in the recovery of the Peninsular bighorn sheep.
    Our Response: Please refer to our response to Comment 5 for the 
statutory definition of critical habitat. The Service may designate as 
critical habitat areas outside the geographical area occupied by a 
species at the time it was listed (i.e., historical habitat) only when 
we can determine that those areas are essential for the conservation of 
the species (section 3(5)(A)(ii) of the Act). We have determined that 
designating critical habitat solely within the geographical area 
occupied by the DPS at the time it was listed will provide for the 
conservation of the Peninsular bighorn sheep. We, therefore, did not 
include areas of historical occupancy that were outside of these areas. 
As previously mentioned in this final rule, critical habitat 
designations do not signal that habitat outside the designation is 
unimportant or may not contribute to a species' recovery. See our 
response to Comment 5 above and the ``Criteria Used To Identify 
Critical Habitat'' section of this final rule for more information.
    Comment 8: One peer reviewer had concerns about designating 
critical habitat based on occupancy at the time of listing. The peer 
reviewer identified what the peer reviewer believed to be two 
shortcomings of this approach, as follows: (1) Critical habitat is 
designated based on the distribution of a species at its lowest 
abundance level, and most likely its most limited spatial distribution, 
thereby reducing the probability of encompassing areas required for 
full recovery; and (2) designated critical habitat assumes that all 
areas have been sufficiently surveyed to document occupancy and doesn't 
address false absences. Another peer reviewer believes that the Service 
failed to recognize false absences as a result of this approach, and 
that this is a grave error because the peer reviewer believes many 
important areas may not be included in the critical habitat 
designation.
    Our Response: In response to the peer reviewer's comment and other 
public comments related to the delineation of critical habitat based on 
occupancy at the time of listing, we revised our criteria used to 
delineate critical habitat as announced in the NOA published in the 
Federal Register on August 25, 2008 (73 FR 50498). As a revision to our 
criteria, we included areas with occupancy data indicating they are 
currently occupied or areas with occupancy data indicating they were 
occupied at some point between 2008

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(present time) and 1988 (i.e., the time of listing (1998) less 10 
years, which is the average lifespan of Peninsular bighorn sheep). Use 
of a data set that considers a larger time-span of occurrence data 
accounts for the large fluctuations in Peninsular bighorn sheep 
population levels over the last two decades, and provides a reasonable 
delineation of the geographical area occupied by the species at the 
time of listing. After rangewide estimates were made in the 1970s, the 
population was estimated as high as 1,171 in 1974 (Weaver 1974, p. 5). 
The population was estimated at 570 individuals in 1988 (Weaver 1989, 
p. 11). We reported in the final listing rule for Peninsular bighorn 
sheep that the population at that time (1998) was approximately 280 
individuals (March 18, 1998, 63 FR 13134). The most recent estimate 
from 2006 puts the population at approximately 800 individuals (Torres 
2007, p. 1). By considering occurrence data between 1988 and the 
present, we are not designating critical habitat based on the 
distribution of the DPS at its lowest abundance level, nor its most 
limited spatial distribution as the peer reviewer suggested.
    We realize that false absences can result from rangewide surveys 
for Peninsular bighorn sheep. Additionally, we are aware that not all 
areas within the range of the DPS have been surveyed or studied 
equally. For example, there is a disproportionate amount of data from 
the northern half of the Peninsular Ranges in the United States, 
compared to the southern half that has not been studied as thoroughly. 
Regardless, we used the best available scientific information and 
occurrence data in determining areas occupied by Peninsular bighorn 
sheep. No information is available to indicate which portions of the 
DPS's range might include false absences.
    Comment 9: One peer reviewer believes that delineation of critical 
habitat must not rely on simple occurrence data alone, but should also 
rely on robust methods of identifying and mapping critical habitat 
based on habitat features.
    Our Response: We agree with the peer reviewer's statement. We 
delineated critical habitat based on occurrence data and a combination 
of habitat features. We designated critical habitat for the Peninsular 
bighorn sheep within areas that we determined were occupied at the time 
of listing and that contain the physical and biological features 
essential to the conservation of the DPS. Lands were designated based 
on sufficient essential features being present to support the life 
processes. Please see our response to Comment 5 and the ``Criteria Used 
To Identify Critical Habitat'' section of this final rule for detailed 
discussions.
    Comment 10: One peer reviewer noted a large number of known 
Peninsular bighorn sheep locations (documented post-listing) that were 
not included in the proposed revised critical habitat and further 
stated that it was unclear why these areas were not included. Another 
peer reviewer listed multiple areas that are documented as occupied at 
or since the time of listing but were not included in the proposed 
critical habitat designation. The peer reviewer indicated that 
occurrence data documenting occupancy were provided to the Service 
prior to the delineation of proposed critical habitat, and further 
stated that these areas provide lambing habitat, foraging areas, 
connectivity between mountainous areas, and important water sources. 
The peer reviewer determined that nearly 1,000 of these locations were 
not included in the proposed critical habitat following an examination 
of occurrence data collected during 2001 to 2003 with the use of Global 
Positioning System (GPS) collars in areas between Highway 74 and the 
southern edge of the Vallecito Mountains. Finally, another peer 
reviewer believes there are large areas without location data of 
Peninsular bighorn sheep that are included as critical habitat and 
areas with bighorn sheep location data that are not included as 
critical habitat.
    Our Response: Upon receiving the peer reviewers' comments, we 
examined the occurrence data considered in the delineation of the 
proposed revised critical habitat and found that a set of data was 
missing from our GIS database. Subsequently, we included that 
occurrence data into our GIS database and double-checked to ensure that 
all occurrence records submitted to the Service were included for our 
analyses. In light of this data and our revised criteria used to 
identify critical habitat (i.e., a data set that includes data since 
1988), we revised our proposed critical habitat boundary, as reported 
in the NOA, to include the areas represented by the location data 
(August 26, 2008, 73 FR 50498).
    Comment 11: One peer reviewer suggested the proposed revised 
critical habitat could have been improved had it been an ``open 
process'' that included the expertise of biologists on the Recovery 
Team, as well as others who have worked with bighorn sheep for decades, 
like what was done for the Peninsular bighorn sheep Recovery Plan. The 
peer reviewer believes that the resulting proposed critical habitat 
designation reflects a hurried process that used arbitrary decision-
making, is not scientifically based, and contradicts the Services' 
Recovery Plan for the DPS.
    Our Response: Contrary to the opinion of the peer reviewer, 
designating critical habitat is an open process. We solicited 
additional expert opinion and public comment through publication of our 
proposed revised rule that was developed using the best scientific data 
available at that point in time. As stated in the proposed rule, 
comments and materials received, as well as supporting documentation 
used in the preparation of the proposed rule, are available for public 
inspection at the Carlsbad Fish and Wildlife Office. In accordance with 
section 4(5)(A) of the Act and the regulations at 50 CFR 424.16(c)(1), 
the Secretary shall--
    (i) Publish notice of the proposal in the Federal Register;
    (ii) Give actual notice of the proposed regulation (including the 
complete text of the regulation) to the State agency in each State in 
which the species is believed to occur, and to each county or 
equivalent jurisdiction therein in which the species is believed to 
occur, and invite the comment of each such agency and jurisdiction;
    (iii) Give notice of the proposed regulation to any Federal 
agencies, local authorities, or private individuals or organizations 
known to be affected by the rule;
    (iv) Insofar as practical, and in cooperation with the Secretary of 
State, give notice of the proposed regulation to list, delist, or 
reclassify a species to each foreign nation in which the species is 
believed to occur or whose citizens harvest the species on the high 
seas, and invite the comment of such nation;
    (v) Give notice of the proposed regulation to such professional 
scientific organizations as the Secretary deems appropriate; and
    (vi) Publish a summary of the proposed regulation in a newspaper of 
general circulation in each area of the United States in which the 
species is believed to occur. Further, the regulations at 50 CFR 
424.16(c)(2) state that at least 60 days shall be allowed for public 
comment following publication in the Federal Register of a rule 
proposing the listing, delisting, or reclassification of a species, or 
the designation or revision of critical habitat.
    On May 14, 2007, representatives from the Carlsbad Fish and 
Wildlife Office and the Regional Office, including the Regional 
Director, met with recovery team members in part to inform members that 
we were initiating work to propose revisions to designated critical 
habitat for the Peninsular

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bighorn sheep. At that meeting, we requested that recovery team members 
submit any data they wanted us to consider in our proposed revision. We 
received data from one recovery team member in response to this 
request.
    During the development of this revision to critical habitat for the 
Peninsular bighorn sheep, we followed the appropriate guidance and 
regulations regarding inclusion of expert biologists and other 
appropriate entities, including the general public. In accordance with 
our policy on peer review published in the Federal Register on July 1, 
1994 (59 FR 34270), we solicited expert opinions from five 
knowledgeable individuals with scientific expertise that included 
familiarity with the DPS, the geographic region in which it occurs, and 
conservation biology principles. We reviewed all comments received from 
the peer reviewers and the public for substantive issues and new 
information regarding the designation of critical habitat for 
Peninsular bighorn sheep.
    Under section 4(f)(2) of the Act, the Secretary may procure the 
services of appropriate public and private agencies and institutions 
and other qualified persons in developing and implementing recovery 
plans. However, the Act limits the use of recovery teams appointed 
under this subsection to the development and implementation of recovery 
plans. The Act does not contain a provision for development of critical 
habitat teams. However, the Service could set up a critical habitat 
team, but it would be subject to the Federal Advisory Committee Act 
(FACA), unlike a recovery team that is exempt from FACA. Since the Act 
contains specific timeframes for completion of critical habitat 
designations, creating a critical habitat team would slow the process 
of designation of critical habitat causing us to be out of compliance 
with the statutory requirements of the Act. However, consistent with 
our peer review policy and the Act's standard of using the best 
available scientific data, we openly and publically solicited 
information for consideration in rule development and solicited peer 
review of our proposal.
    In total, we received comments from all five peer reviewers that we 
solicited comments from, and we received 5,299 comments from the 
general public during two public comment periods and two public 
hearings. Therefore, we believe we followed an open process during 
development of the Peninsular bighorn sheep revised critical habitat 
designation.
    Regarding the peer reviewer's beliefs that the proposed critical 
habitat designation reflects a hurried process that used arbitrary 
decision-making and was not scientifically based, we disagree with this 
comment. As noted above, we solicited information from the entire 
Peninsular bighorn sheep recovery team prior to the proposed revisions 
to the designation. We also solicited expert opinions from five 
knowledgeable individuals with scientific expertise that included 
familiarity with the DPS, the geographic region in which it occurs, and 
conservation biology principles. Additionally, the designation of 
critical habitat for Peninsular bighorn sheep is based on the best 
scientific data available regarding the DPS, including: (1) A 
compilation of data from peer-reviewed, published literature; (2) 
unpublished or non-peer reviewed survey and research reports; and (3) 
opinions of biologists knowledgeable about Peninsular bighorn sheep and 
their habitat (see our response to Comment 5 and the ``Criteria Used To 
Identify Critical Habitat'' section for additional discussion on use of 
available scientific data and how this data was used to develop 
criteria for identifying critical habitat).
    Comment 12: One peer reviewer believes it is impossible to 
duplicate the delineation of the revised critical habitat based on the 
Service's poorly described methods and an inadequate explanation of how 
the PCEs were used to delineate critical habitat. Another peer reviewer 
believes the proposed rule does not provide specifics on how proposed 
revised critical habitat was delineated, nor does it include discussion 
of the actual methods of identifying and mapping the PCEs. The same 
peer reviewer stated that along several sections of the proposed 
revised critical habitat boundary, the boundary line follows a 
perfectly straight course, which does not appear to conform to (or 
follow) any obvious biological or topographical feature; therefore, the 
peer reviewer questioned how this boundary line was placed. Another 
peer reviewer could not identify the specific methods used to create 
the revised boundary of the proposed rule and further stated that the 
boundary lines give the appearance of being hand-drawn, rather than 
based on a scientific method.
    Our Response: As discussed in our response to Comment 5 above and 
the ``Criteria Used To Identify Critical Habitat'' section of this 
final rule, we delineated critical habitat for the Peninsular bighorn 
sheep using the following criteria: (1) Areas that contain the PCEs 
required by the DPS as determined from aerial imagery and GIS data on 
vegetation, elevation, and slope; (2) areas within the ewe group 
distribution (i.e., subpopulations) boundaries identified by Rubin et 
al. (1998); (3) areas occupied by the subspecies between 2008 (present 
time) and 1988; and (4) areas where occupancy data points indicate 
repeated Peninsular bighorn sheep use, but which were not captured 
within the ewe group distribution boundaries identified by Rubin et al. 
(1998). Application of these criteria results in the determination of 
the physical and biological features that are essential to the 
conservation of this DPS, identified as the DPS's PCEs laid out in the 
appropriate quantity and spatial arrangement essential to the 
conservation of the DPS. Since the 2007 proposed rule, we revised the 
``Criteria Used To Identify Critical Habitat'' section of this rule to 
provide more detail and description of the stepwise process used, data 
considered, habitat features mapped, and method used to delineate 
critical habitat boundaries. The boundaries were drawn with GIS 
software using detailed aerial imagery maps and data layers of 
occurrences and habitat information. Any straight lines along the 
boundary of critical habitat are the result of following habitat 
features that are naturally straight in appearance.
    Comment 13: One peer reviewer asked if a model was employed, and if 
so, describe the type and state whether it was based on expert opinion.
    Our Response: We did not use a model to delineate critical habitat 
for the Peninsular bighorn sheep. For more information on how we 
delineated critical habitat, see the ``Criteria Used To Identify 
Critical Habitat'' section of this final rule.
    Comment 14: One peer reviewer inquired as to whether or not PCEs 
were weighted in the process of revising critical habitat.
    Our Response: The PCEs were not weighted in the process of revising 
critical habitat.
    Comment 15: One peer reviewer expressed concern that Anza Borrego 
Desert State Park's vegetation maps were not utilized in the critical 
habitat revision. The peer reviewer believes that vegetation has a 
critical influence on what type of habitat the Peninsular bighorn sheep 
use; therefore, he asserts that this information would have been 
instrumental in delineating a more accurate critical habitat boundary. 
Another peer reviewer asked which vegetation layer was used in 
delineating critical habitat.
    Our Response: We believed it was important to use a GIS vegetation 
data

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layer that provided a consistent analysis over the entire extent of the 
Peninsular bighorn sheep range. Any vegetation layers that were 
prepared for a specific entity, including a park (such as Anza Borrego 
Desert State Park) or individual county, were not all-encompassing and 
therefore inappropriate for the analysis. The proposed and final 
revised critical habitat includes land in three separate counties 
(Imperial, Riverside, and San Diego). Therefore, the GIS layer that we 
used for the vegetation analysis portion of defining proposed critical 
habitat for the Peninsular bighorn sheep was the Fire and Resource 
Assessment Program layer created by the California Department of 
Forestry and Fire Protection. For further information on this 
vegetation data, see their Web site at: https://frap/cdf/ca/gov. This 
vegetation layer was most appropriate because it extended over the 
entire area of the Peninsular Ranges and allowed for consistency in our 
analysis of vegetation across the range of this DPS.
    Comment 16: One peer reviewer was concerned that our methodology 
included an elevation cut-off of 4,600 ft (1,400 m) to guide the 
critical habitat boundary line. The peer reviewer stated that, at 
times, Peninsular bighorn sheep rely on areas higher than this, 
especially on the western side of the Santa Rosa Mountains.
    Our Response: We acknowledge that Peninsular bighorn sheep have 
occasionally been observed above 4,600 ft (1,400 m) elevation; however, 
it is commonly accepted that sheep within the Peninsular Ranges are 
primarily restricted to lower elevations (see the ``Primary Constituent 
Elements (PCEs)'' section for more information). We do not have 
evidence to suggest that areas above 4,600 ft (1,400 m) elevation are 
essential for the conservation of this DPS, and the commenter did not 
provide information to support the assertion that sheep rely on higher 
elevations. As previously mentioned in this final rule, critical 
habitat designations do not signal that habitat outside of the 
designation is unimportant or may not contribute to recovery (see our 
response to Comment 1 above).
    Comment 17: One peer reviewer stated that the rule indicates that 
areas with canopy cover greater than 30 percent were not included as 
critical habitat. The peer reviewer asked what information was used to 
determine this cut-off point and what GIS data layer was used to 
identify these areas.
    Our Response: Generally, bighorn sheep primarily rely on their 
sense of sight to detect predators. Research shows that bighorn sheep 
will avoid habitat where dense vegetation reduces visibility and, 
instead, prefer to use habitat with vegetative canopy cover less than 
or equal to 30 percent (Risenhoover and Bailey 1985, p. 799; Etchberger 
et al. 1989, p. 906; Dunn 1996, p. 1). Bighorn sheep in the Peninsular 
Ranges avoid higher elevations (above 4,600 ft (1,400 m)), likely due 
to decreased visibility (and therefore increased predation risk) 
associated with denser vegetation (i.e., chaparral and conifer 
woodland) found at higher elevations (Service 2000, p. 10).
    The GIS layer that was used for the vegetation analysis for the 
proposed revised critical habi