[Federal Register: March 18, 1998 (Volume 63, Number 52)]
[Rules and Regulations]               
[Page 13134-13150]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18mr98-16]

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AB73

 
Endangered and Threatened Wildlife and Plants; Endangered Status 
for the Peninsular Ranges Population Segment of the Desert Bighorn 
Sheep in Southern California

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: The U.S. Fish and Wildlife Service (Service) determines the 
distinct vertebrate population segment of bighorn sheep (Ovis 
canadensis) (Peninsular bighorn sheep) occupying the Peninsular Ranges 
of southern California, to be an endangered species pursuant to the 
Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.), as amended 
(Act). The Service originally proposed to list the Peninsular bighorn 
sheep throughout its range, which extends into Baja California, Mexico. 
However, because new information received during the comment periods 
indicated listing bighorn sheep populations in Baja California is not 
warranted, the final listing determination includes only the Peninsular 
bighorn sheep population segment in the United States. The synergistic 
effects of disease; low recruitment; habitat loss, degradation, and 
fragmentation; non-adaptive behavioral responses associated with 
residential and commercial development; and high predation rates 
coinciding with low bighorn sheep population numbers threaten the 
continued existence of these animals in southern California. This rule 
implements Federal protection and recovery provisions of the Act for 
the Peninsular bighorn sheep. Critical habitat is not being designated.

DATES: This rule is effective March 18, 1998.

ADDRESSES: The complete file for this rule is available for inspection, 
by appointment, during normal business hours at the U.S. Fish and 
Wildlife Service, Carlsbad Field Office, 2730 Loker Avenue West, 
Carlsbad, California 92008.

FOR FURTHER INFORMATION CONTACT: Arthur Davenport, at the above address 
(telephone: 760/431-9440).

Background

    The bighorn sheep (Ovis canadensis) is a large mammal (family 
Bovidae) originally described by Shaw in 1804

[[Page 13135]]

(Wilson and Reeder 1993). Several subspecies of bighorn sheep have been 
recognized on the basis of geography and differences in skull 
measurements (Cowan 1940, Buechner 1960). These subspecies of bighorn 
sheep, as described in this early work, include O. c. cremnobates 
(Peninsular bighorn sheep), O. c. nelsoni (Nelson bighorn sheep), O. c. 
mexicana (Mexican bighorn sheep), O. c. weemsi (Weems bighorn sheep), 
O. c. californiana (California bighorn sheep), and O. c. canadensis 
(Rocky Mountain bighorn sheep). However, as discussed later, recent 
genetic studies question the validity of some of these subspecies and 
reveal the need to reevaluate bighorn sheep taxonomy. Regardless of the 
taxonomy, Peninsular bighorn sheep in southern California meet the 
Service's criteria for consideration as a distinct vertebrate 
population segment and are treated as such in this final rule.
    Bighorn sheep (Ovis canadensis) are found along the Peninsular 
Mountain Ranges from the San Jacinto Mountains of southern California 
south into the Volcan Tres Virgenes Mountains near Santa Rosalia, Baja 
California, Mexico, a total distance of approximately 800 kilometers 
(km) (500 miles (mi)). The area occupied by the distinct vertebrate 
population segment covered in this final rule coincides with the range 
of the currently questioned subspecies O. c. cremnobates in California. 
The California Fish and Game Commission listed O. c. cremnobates as 
``rare'' in 1971. The designation was changed to ``threatened'' by the 
California Department of Fish and Game (CDFG) to conform with 
terminology of the amended California Endangered Species Act (CESA).
    The Peninsular bighorn sheep is similar in appearance to other 
desert associated bighorn sheep. The species' pelage (coat) is pale 
brown, and its permanent horns, which become rough and scarred with 
age, vary in color from yellowish-brown to dark brown. The horns are 
massive and coiled in males; in females, they are smaller and not 
coiled. In comparison to other desert bighorn sheep, the Peninsular 
bighorn sheep is generally described as having paler coloration and 
larger and heavier horns that are moderately divergent at the base 
(Cowan 1940).
    The habitat still remaining for the Peninsular bighorn sheep in the 
United States is managed by the California Department of Parks and 
Recreation (CDPR) (46 percent), Bureau of Land Management (BLM) (27 
percent), private landowners (24 percent), Bureau of Indian Affairs (1 
percent), U.S. Forest Service (USFS) (1 percent), and other State 
agencies (1 percent) (BLM 1993).
    The Peninsular bighorn sheep occurs on open slopes in hot and dry 
desert regions where the land is rough, rocky, sparsely vegetated and 
characterized by steep slopes, canyons, and washes. Most of these sheep 
live between 91 and 1,219 meters (m) (300 and 4,000 feet (ft)) in 
elevation where average annual precipitation is less than 10 
centimeters (cm) (4 inches (in)) and daily high temperatures average 
104 deg. Fahrenheit in the summer. Caves and other forms of shelter 
(e.g., rock outcrops) are used during inclement weather. Lambing areas 
are associated with ridge benches or canyon rims adjacent to steep 
slopes or escarpments. Alluvial fan areas are also used for breeding 
and feeding activities.
    From May through October, bighorn sheep are dependent on permanent 
sources of water and are more localized in distribution. Bighorn sheep 
populations aggregate during this period due to a combination of 
breeding activities and diminishing water sources. Summer concentration 
areas are associated primarily with dependable water sources, and 
ideally provide a diversity of vegetation to meet the forage 
requirements of bighorn sheep.
    Bighorn sheep species are diurnal. Their daily activity pattern 
consists of feeding and resting periods that are not synchronous either 
within or between groups, as some sheep will be resting while others 
are feeding. Browse is the dominant food of desert-associated bighorn 
sheep. Plants consumed may include brittlebrush (Encelia sp.), mountain 
mahogony (Cercocarpus sp.), Russian thistle (Salsola sp.), bursage 
(Hyptis sp.), mesquite (Proposis sp.), palo verde (Cercidium sp.), and 
coffeeberry (Rhamnus sp.). During the dry season, the pulp and fruits 
of various cacti are eaten. Native grasses are eaten throughout the 
year and are important food, especially near waterholes.
    Bighorn sheep species produce only one lamb per year. The gestation 
period is about 5 to 6 months (Geist 1971). Lambing occurs between 
January and June, with most lambs being born between February and May. 
Lactating ewes and young lambs congregate near dependable water sources 
in the summer. Ewes and lambs frequently occupy steep terrain that 
provides a diversity of slopes and exposures for escape cover and 
shelter from excessive heat. Lambs are precocial and within a day or so 
climb as well as the ewes. Lambs are able to eat native grass within 2 
weeks of their birth and are weaned between 1 and 7 months of age. By 
their second spring, bighorn sheep lambs are independent of the ewes 
and, depending upon physical condition, may attain sexual maturity 
during the second year of life (Cowan and Geist 1971, Geist 1971).

Distinct Vertebrate Population Segment

    Recent analyses of bighorn sheep genetics and morphometrics suggest 
that the taxonomy of Peninsular bighorn sheep needs to be reevaluated 
(Ramey 1991, Whehausen and Ramey 1993, Boyce et al. 1997). A recent 
analysis of the taxonomy of bighorn sheep using morphometrics (e.g., 
size and shape of skull components) failed to support the current 
taxonomy (Wehausen and Ramey 1993). Ramey (1995) found little genetic 
variation among desert bighorn sheep using restriction fragment length 
polymorphism (RFLP) analysis.
    By contrast, Boyce et al. (1997) found high genetic diversity 
within and between populations of desert bighorn sheep. In this study, 
microsatelite loci (MS) and major histocompatibility complex (MHC) were 
analyzed. It appears that the results of Ramey (1995) and Boyce et al. 
(1997) differ because dissimilar molecular markers were analyzed. That 
is, the choice of molecular markers (e.g., mtDNA, microsatelites, 
allozymes) and analytical techniques (RFLP, DNA sequencing, etc.) 
apparently influence both the discriminating power of the techniques 
and conclusions relating to the genetic variability of a species.
    Ongoing research into the genetic variation of bighorn sheep using 
a refined technique of mtDNA analysis (i.e., DNA sequencing) has 
resulted in the discovery of significantly higher genetic variation in 
mtDNA of the Peninsular bighorn sheep than was found by Ramey (Walter 
Boyce, DVM, Ph.D. and Esther Rubin, University of California at Davis, 
in litt., 1997). Boyce and Rubin found several matriarchal lines where 
Ramey (1995) found only one. The difference in results apparently is a 
result of the increased resolution provided by the technique used by 
Boyce and Rubin (Walter Boyce, DVM, Ph.D. and Esther Rubin, University 
of California at Davis, in litt., 1997). Regardless how the taxonomy 
issue is finally resolved, the biological evidence supports recognition 
of Peninsular bighorn sheep as a distinct vertebrate population segment 
for purposes of listing as defined in the Service's February 7, 1996, 
Policy Regarding the Recognition of Distinct Vertebrate Population 
Segments (61 FR 4722).
    The definition of ``species'' in section 3(16) of the Act includes 
``any distinct

[[Page 13136]]

population segment of any species of vertebrate fish or wildlife which 
interbreeds when mature.'' For a population to be listed under the Act 
as a distinct vertebrate population segment, three elements are 
considered--(1) the discreteness of the population segment in relation 
to the remainder of the species to which it belongs; (2) the 
significance of the population segment to the species to which it 
belongs; and (3) the population segment's conservation status in 
relation to the Act's standards for listing (i.e., is the population 
segment, when treated as if it were a species, endangered or 
threatened?) (61 FR 4722).
    The distinct population segment of bighorn sheep in the Peninsular 
Ranges is discrete in relation to the remainder of the species as a 
whole. This population segment is geographically isolated and separate 
from other desert bighorn sheep. This is supported by an evaluation of 
the population's genetic variability and metapopulation structure 
(Boyce et al. 1997). The genetic distance found to exist between the 
Peninsular bighorn sheep and their nearest neighbors at the north end 
of the range (i.e., bighorn sheep occupying the Orocopia, Eagle, and 
San Gorgonio mountains) was three times greater than that found within 
subpopulations of Peninsular bighorn sheep sampled (Boyce et al. 1997). 
Genetic distance is a measure of the degree of genetic difference 
(divergence) between individuals, populations, or species.
    The distinct vertebrate population segment covered in this final 
rule extends from the northern San Jacinto Mountains to the 
international border between the United States and Mexico. The range of 
Peninsular bighorn sheep in Mexico extends southward into the Volcan 
Tres Virgenes Mountains, located just north of Santa Rosalia, Baja 
California, Mexico, and is not addressed in this rulemaking. In 
accordance with distinct vertebrate population segment policy, the 
Service may determine a population to be discreet at an international 
border where there are significant differences in (1) the control of 
exploitation; (2) management of habitat; (3) conservation status, or 
(4) regulatory mechanisms (61 FR 4722). In the case of the Peninsular 
bighorn sheep, there are significant differences between the United 
States and Mexico in regard to the species' conservation status.
    Information received from the Mexican Government indicates the 
population in Baja California is not likely to be in danger of 
extirpation within the foreseeable future because there are 
significantly more animals there than occur in the United States 
(Felipe Ramirez, Mexico Institute of Ecology, in litt. 1997). Based on 
DeForge et al. (1993) there are estimated to be between 780 and 1,170 
adult Peninsular bighorn sheep in Baja California, Mexico, north of 
Bahia San Luis Gonzaga. In addition to the higher population numbers, 
the Mexican Government has initiated a conservation program for bighorn 
sheep that should improve the status of these animals. Based on 
information received from the Mexican Government, components of the 
conservation program include the involvement of the local people in the 
establishment of conservation and management units that allow some use 
of the bighorn sheep while promoting its conservation and recovery. 
Approximately 1,199,175 ha (485,306 ac) have been included in this 
program for Peninsular bighorn sheep.
    Peninsular bighorn sheep are biologically and ecologically 
significant to the species in that they constitute one of the largest 
contiguous metapopulations of desert bighorn sheep. The metapopulation 
spans approximately 160 km (100 mi) of contiguous suitable habitat in 
the United States. The loss of Peninsular bighorn sheep in the United 
States would isolate bighorn sheep populations in Mexico, including the 
Weems subspecies, from all other bighorn sheep, thereby producing a 
significant gap in the range of bighorn sheep. In addition, the 
Peninsular bighorn sheep occur in an area that has marked climatic and 
vegetational differences as compared to most other areas occupied by 
bighorn sheep. The majority of the range of the Peninsular bighorn 
sheep is classified as Colorado Desert, a subarea of the Sonoran 
Desert. This area experiences significantly different climatic 
variation (e.g., timing and/or intensity of rainfall) than the Mojave 
or other Sonoran deserts and contains a somewhat different flora 
(Monson and Sumner 1990, Hickman 1993). Though rainfall is greater in 
the higher mountains (e.g., San Jacintos), rainfall averages less than 
13 mm (5 in) and snow is almost unknown in most of this area (Monson 
and Sumner 1990). It is important to note that the Peninsular bighorn 
sheep do not typically occur above 1,200 m (4,000 ft) in the higher 
mountains (Monson and Sumner 1990). This is unusual because bighorn 
sheep typically occupy higher elevational habitat that contains sparse 
vegetative cover. The low amount of rainfall, high evapotranspiration 
rate, and temperature regime in the majority of the Peninsular bighorn 
sheep's range is notably different from other North American deserts. 
The species' ability to exist under these conditions suggests unique 
behavioral and/or physiological adaptations.
    Recent information further supports the significance of the 
Peninsular bighorn sheep to the overall species. Based on an evaluation 
of the population's genetic variability by Boyce et al. (1997) and 
Ramey (1995), the Peninsular bighorn sheep contain a large portion of 
the total genetic diversity of the species. Based on these initial 
studies, there is at least one distinct haplotype (Ramey 1995) and one 
unique MS allele (Boyce et al. 1997) that are restricted entirely to 
Peninsular bighorn sheep. High genetic diversity indicates a capacity 
to adapt to a changing environment.

Status and Distribution

    The Peninsular bighorn sheep in the United States declined from an 
estimated 1,171 individuals in 1971 to about 450-600 individuals in 
1991 (CDFG 1991). Recent population estimates indicate continued 
decline, and Peninsular bighorn sheep in the United States now number 
approximately 280 (DeForge et al. 1995, J. Deforge, in litt., 1997, E. 
Rubin and W. Boyce, in litt., 1996, W. Boyce and E. Rubin, in litt., 
1997). The population of Peninsular bighorn sheep in the United States 
is currently divided amongst approximately eight ewe groups.
    About 20 Peninsular bighorn sheep are held in captivity at the 
Bighorn Institute in Palm Desert, California. The Bighorn Institute, a 
private, nonprofit organization, was established in 1982 to initiate a 
research program for the Peninsular bighorn sheep. The Living Desert, 
an educational and zoo facility also located in Palm Desert, 
California, maintains a group of 10 to 12 Peninsular bighorn sheep at 
its facility.
    The continuing decline of the Peninsular bighorn sheep is 
attributed to a combination of factors, including: (1) the effects of 
disease (Buechner 1960, DeForge and Scott 1982, DeForge et al. 1982, 
Jessup 1985, Wehausen et al. 1987, Elliott et al. 1994); (2) low 
recruitment (DeForge et al. 1982, Wehausen et al. 1987, DeForge et al. 
1995); (3) habitat loss, degradation, and fragmentation (J. DeForge, in 
litt., 1997, David H. Van Cleve, CDPR, in litt., 1997, USFWS, unpub. 
info., 1997); (4) and, more recently, high rates of predation 
coinciding with low population numbers (W. Boyce and E. Rubin, in litt. 
1997).

[[Page 13137]]

Previous Federal Action

    On September 18, 1985, the Service designated the Peninsular 
bighorn sheep as a category 2 candidate and solicited status 
information (50 FR 37958). Category 2 included taxa for which the 
Service had information indicating that proposing to list as endangered 
or threatened was possibly appropriate, but for which sufficient data 
on biological vulnerability and threats were not currently available to 
support a proposed rule. In the January 6, 1989 (54 FR 554), and 
November 21, 1991 (56 FR 58804), Notices of Review, the Peninsular 
bighorn sheep was retained in category 2. In 1990, the Service 
initiated an internal status review of these animals. This review was 
completed in the spring of 1991 resulting in a change from category 2 
to category 1 designation. Category 1 were those taxa for which the 
Service had sufficient information on biological vulnerability and 
threats to support proposals to list them as endangered or threatened. 
This change to category 1 was inadvertently omitted from the November 
21, 1991, Animal Notice of Review (56 FR 58804).
    On July 15, 1991, the Service received a petition from the San 
Gorgonio Chapter of the Sierra Club to list the Peninsular bighorn 
sheep as an endangered species. The petition requested that the Service 
list the Peninsular bighorn sheep throughout its entire range, or, at 
least, list the population occurring in the Santa Rosa and San Jacinto 
mountains of southern California, through emergency or normal 
procedures. The Service used information from the status review and the 
July 15, 1991, petition to determine that substantial information 
existed indicating that the Peninsular bighorn sheep may be in danger 
of extinction throughout all or a significant portion of its range. 
This finding was made on December 30, 1991, pursuant to section 
4(b)(3)(A) of the Act and was published in the Federal Register on May 
8, 1992, as a proposed rule to list the Peninsular bighorn sheep as 
endangered (57 FR 19837). The proposed rule constituted the 1-year 
finding for the July 15, 1991, petitioned action. The proposed listing 
status was reconfirmed in the November 15, 1994 (59 FR 58982), and 
February 28, 1996, (61 FR 7596), and September 19, 1997 (62 FR 49398) 
Notices of Review. On February 14, 1995, the Sierra Club Legal Defense 
Fund (plaintiff) filed suit in Federal District Court for the Eastern 
District of California to compel the Secretary of the Interior and the 
Director of the Service to make a final determination to list the 
Peninsular bighorn sheep as an endangered or threatened species.
    On April 10, 1995, Congress enacted a moratorium prohibiting work 
on listing actions (Public Law 104-6), thus preventing the Service from 
taking final listing action on the Peninsular bighorn sheep. The 
moratorium was lifted on April 26, 1996, by means of a Presidential 
waiver, at which time limited funding for listing actions was made 
available through the Omnibus Appropriations Act (Pub. L. No. 104-134, 
100 Stat. 1321, 1996). The Service published guidance for restarting 
the listing program on May 16, 1996 (61 FR 24722).
    In response to the Sierra Club Legal Defense Fund suit, the 
District Court issued a stay order on April 10, 1996. On October 15, 
1996, the plaintiff asked the Court to lift the stay and require the 
final Peninsular bighorn sheep listing decision within 30 days. On 
November 26, the District Court entered an order denying the 
plaintiff's request to lift the stay, but certified the issue 
underlying that denial for interlocutory appeal. The case is currently 
on interlocutory appeal before the Ninth Circuit Court of Appeals.
    Due to new information becoming available during the lapse between 
the original comment period (November 4, 1992) and lifting of the 
listing moratorium, the Service reopened the public comment period on 
April 7, 1997, for 30 days (62 FR 16518). That comment period closed 
May 7, 1997. Because of additional requests, the Service reopened the 
public comment period on June 17, 1997, for an additional 15 days (62 
FR 32733), and then again on October 27, 1997, for another 15 days (62 
FR 55563).
    The processing of this final rule conforms with the Service's final 
listing priority guidance as published in the Federal Register on 
December 5, 1996 (61 FR 64475) and subsequently extended on October 23, 
1997 (62 FR 55268). The guidance clarifies the order in which the 
Service will process rulemakings. The guidance calls for giving highest 
priority to handling emergency situations (Tier 1), second highest 
priority (Tier 2) to resolving the listing status of the outstanding 
proposed listings, third priority (Tier 3) to new proposals to add 
species to the list of threatened and endangered plants and animals and 
fourth priority (Tier 4) to processing critical habitat determinations 
and delistings. This final rule constitutes a Tier 2 action. This rule 
constitutes the final determination resulting from the listing proposal 
and all comments received during the comment periods.

Summary of Comments and Recommendations

    In the May 8, 1992, proposed rule (57 FR 19837) and associated 
notifications, all interested parties were requested to submit factual 
reports or information that might contribute to the development of a 
final rule for the Peninsular bighorn sheep. Appropriate State 
agencies, county governments, Federal agencies, scientific 
organizations, and other interested parties were contacted and 
requested to comment. Legal notices were published in the Riverside 
Press-Enterprise and the San Diego Union-Tribune on May 26, 1992, and 
invited general public comment on the proposal. No public hearings were 
conducted.
    In compliance with Service policy on information standards under 
the Act (59 FR 34270; July 1, 1994), the Service solicited the expert 
opinions of three appropriate and independent specialists regarding 
pertinent scientific or commercial data and issues relating to the 
taxonomy, population models, and supportive biological and ecological 
information for the Peninsular bighorn sheep. In addition, their 
opinions were solicited on the discreteness and significance of the 
Peninsular bighorn sheep. The responses received from two of the 
reviewers supported the proposed listing action and provided additional 
insight into the discreteness and significance of the population. All 
three reviewers commented on the taxonomy of bighorn sheep and the 
general need for a reevaluation of this group. The third reviewer did 
not comment on the discreteness or significance of the Peninsular 
bighorn sheep nor make a recommendation concerning the listing action. 
Information and suggestions provided by the reviewers were considered 
in developing this final rule, and incorporated where applicable.
    During the initial 6-month comment period the Service received a 
total of 56 comments, including 14 that were submitted after the 
comment period closed. (Multiple comments from the same party on the 
same date were regarded as one comment.) Of these, 40 (71 percent) 
supported the listing, ten (18 percent) opposed the listing, and six 
(11 percent) were non-committal. During this initial period, the BLM 
and the Bighorn Institute took a neutral stance on the proposal. The 
CDPR, six conservation organizations, four local governments, and 30 
other groups or individuals supported listing. The CDFG, the Desert 
Bighorn Council, and several property owners opposed the listing.

[[Page 13138]]

    During the three subsequent extensions of the public comment 
period, the Service received a total of 49 responses (multiple/same 
issue comments received from a single party were regarded as one 
comment). Of these, 36 (73 percent) supported the listing, ten (20 
percent) opposed the listing, and four (8 percent) were non-committal.
    During the first comment period extension, the BLM and the Bighorn 
Institute recommended listing the Peninsular population as endangered. 
The CDPR and one conservation organization reaffirmed their support for 
the listing of the Peninsular bighorn sheep as endangered. On May 6, 
1997, MCO Properties, Inc. made an untimely request for public hearing. 
In lieu of a hearing, the Service extended the public comment period a 
second time.
    Subsequent to the second public comment period extension, the 
Mexican Government expressed an interest in the potential listing of 
the Peninsular bighorn sheep. To acquire additional information on the 
status, distribution, and management of bighorn sheep in Baja 
California, Mexico, the public comment period was reopened on October 
27, 1997 (62 FR 55563). During this third and last comment period 
extension, the Mexican Government submitted information pertinent to 
the listing proposal (F. Ramirez, in litt. 1997). In particular, the 
Mexican Government reported on population numbers and the institution 
of a new conservation program for bighorn sheep. Due in part to the 
implementation of this conservation program, the southern boundary of 
the distinct vertebrate population segment was re-delineated at the 
United States/Mexico International Border.
    The Service reviewed all of the written comments referenced above. 
The comments were grouped and are discussed under the following issues. 
In addition, all biological and commercial information obtained through 
the public comment period have been considered and incorporated, as 
appropriate, into the final rule.
    Issue 1: Several commenters contended that the subspecific taxonomy 
of Ovis canadensis was the subject of scientific debate that should be 
resolved before the Service finalizes this action. At a minimum, the 
Service should consider a listing of O. c. cremnobates rather than a 
population.
    Service Response: The Service concurs that the taxonomy of the 
Peninsular bighorn sheep is in need of further scientific review. 
However, the final listing determination for the Peninsular bighorn 
sheep was based on analysis as a distinct vertebrate population 
segment. Section 3(16) of the Act defines a species to include ``* * * 
any distinct population segment of any species of vertebrate fish or 
wildlife which interbreeds when mature.'' To guide decisions to 
recognize distinct vertebrate population segments the Service 
established policy on February 7, 1996 (61 FR 4722). The recognition of 
Peninsular bighorn sheep as a distinct vertebrate population segment is 
consistent with this policy and the biological status of this bighorn 
sheep group warrants such designation. See further discussion of this 
issue under the Distinct Vertebrate Population Segment section of this 
rule.
    Issue 2: One commenter stated that bighorn sheep in Baja 
California, Mexico, were distinct from those occurring in southern 
California, and should therefore not be listed.
    Service Response: The southern demarcation for the distinct 
vertebrate population segment was moved to the United States/Mexico 
International Border because a discreteness condition regarding a 
political boundary between two countries was satisfied. However, based 
on the best available biological information there is no indication 
that Peninsular bighorn sheep in Baja California, Mexico, are 
biologically distinct from those in California. The commenter did not 
provide additional information supporting this statement.
    Issue 3: One commenter observed that the proposed rule did not 
comply with the policy on recognizing distinct vertebrate population 
segments.
    Service Response: The proposed rule was published prior to the 
publication of the Service's policy on recognizing distinct vertebrate 
population segments (61 FR 4722). The final rule, in addressing only 
Peninsular bighorn sheep occurring in southern California, satisfies 
the policy. A discreteness condition of the policy recognizes the 
validity of delimiting population segments ``by international 
governmental boundaries within which differences in control of 
exploitation, management of habitat, conservation status, or regulatory 
mechanisms exist.'' See the section on Distinct Vertebrate Population 
Segment and its relation to the Peninsular bighorn sheep for further 
discussion of this issue.
    Issue 4: Several commenters expressed concern that data from only a 
limited portion of the Peninsular Ranges in California (i.e., the Santa 
Rosa Mountains) was being used to characterize the overall status of 
the Peninsular bighorn sheep. In addition, the commenters stated that 
no attempt was made to gather and analyze data for other portions of 
this population's range (e.g., Mexico, Anza Borrego State Park).
    Service Response: The Service has sought and evaluated all 
available information submitted during the public comment periods or 
otherwise available to determine this final listing action including 
information specifically related to Peninsular bighorn sheep 
populations located in areas other than the Santa Rosa Mountains. 
Information on threats and impacts to Peninsular bighorn sheep was 
obtained from those conducting research specific to this population 
segment. In addition, information on threats affecting bighorn sheep 
throughout the United States (e.g., see Geist 1971, Krausman and 
Leopold 1986) also was used as a reference to evaluate potential 
impacts on Peninsular bighorn sheep.
    Although data were not available to plot specific population trends 
for all portions of the Peninsular bighorn sheep range (such as that in 
Mexico) (Alvarez 1976, Sanchez et al. 1988, Monson 1980, DeForge et al. 
1993, Lee and Mellink 1996), there is a marked difference in recent and 
historic population estimates. Based on these estimates, there appears 
to have been a decline in the number of Peninsular bighorn sheep in 
Baja California, Mexico. It is not surprising that Peninsular bighorn 
sheep have declined in Baja California, Mexico, given the presence of 
the same factors identified for the decline in the United States (e.g., 
introduced pathogens). Although there is no empirical evidence that 
active epizootics are occurring at this time, the same diseases that 
have been implicated in the mortality of Peninsular bighorn sheep in 
the Santa Rosa Mountains have been detected in Peninsular bighorn sheep 
within Anza Borrego State Park (Clark et al. 1985), and Baja 
California, Mexico (J. DeForge, pers. comm., 1997). However, recent 
information provided by the Mexican government (F. Ramirez, in litt. 
1997), regarding bighorn sheep found on the peninsula of Baja 
California, Mexico, supports the position that the Mexican population 
is not likely to be in danger of extirpation within the foreseeable 
future. Therefore, Peninsular bighorn sheep are not being listed in 
Mexico at this time.
    Issue 5: Several commenters questioned a decline in the population 
numbers of Peninsular bighorn sheep. In addition, two of the commenters 
stated the information used in the proposed rule was speculative in 
nature. Another commenter observed that the population had remained 
stable over the past 7 years and, therefore, it was premature to list 
this species.

[[Page 13139]]

    Service Response: The Service is required to base listing decisions 
on the best available scientific and commercial information available. 
Based on this information, the Service concludes that the Peninsular 
bighorn sheep has undergone a significant decline over much of its 
range since 1971 and there is a danger of extinction of this distinct 
population segment. See sections on Status and Distribution and Summary 
of Factors Affecting the Species for further discussion of this issue.
    Issue 6: One commenter claimed that inadequate surveys have been 
conducted for Peninsular bighorn sheep in Baja California, Mexico.
    Service Response: The Service agrees that, even under optimum 
conditions, it is difficult to detect each individual animal in a 
population during a survey. However, the survey methodology used by 
DeForge et al. (1993) (i.e., the use of a helicopter) is an accepted 
reliable method for censusing bighorn sheep populations.
    Issue 7: One commenter expressed concern regarding the use of 
single-year data for sheep recruitment rates. The commenter stated that 
this use was not statistically valid or indicative of long-term trends 
and argued that high adult survivorship combined with pulses of good 
recruitment can counter a year of poor recruitment and allow the 
bighorn sheep to thrive. The commenter further suggested that data from 
Anza Borrego Desert State Park did not suggest clear and consistent 
declines in recruitment.
    Service Response: The Service concurs with the general concerns of 
the commenter regarding the use of single year data versus long-term 
data in determining population trends. Single-year data were used as an 
example, in the proposed rule, of the potential effects of introduced 
disease on Peninsular bighorn sheep. Moreover, the example of low 
recruitment was also used for purposes of clarification. There is 
substantial information to support the conclusion that poor recruitment 
has been one of several factors contributing to the species' decline 
since at least 1977 (DeForge and Scott 1982, DeForge et al. 1982, 
Wehausen et al. 1987, Weaver 1989, Elliott et al. 1994, DeForge et al. 
1995). As for the status of the Peninsular bighorn sheep, the 
population in the United States has declined from an estimated 1,171 
individuals in 1971 to approximately 280 in 1997 (CDFG 1991, E. Rubin 
and W. Boyce, in litt. 1996; W. Boyce and E. Rubin, in litt. 1997). The 
overall precipitous decline is evident from years of data from 
representative portions of the range of the Peninsular bighorn sheep, 
(Wehausen et al. 1987, Sanchez et al. 1988, Weaver 1989, CDFG 1991, 
DeForge et al. 1995, Rubin et al. 1997).
    Issue 8: One commenter questioned the validity of portions of the 
Service's analysis under Factor E (natural or manmade threats) in the 
proposed rule. The commenter additionally stated that the relative 
importance of population size, recruitment, and inbreeding in 
influencing the species' status was diminished because the Service did 
not take the metapopulation structure of the population into 
consideration. The commenter went on to contend the factors acting on 
small populations that Berger (1990) investigated were not necessarily 
limiting the Peninsular bighorn sheep and that his conclusions were 
speculative in nature. Another commenter questioned the scientific 
validity of Berger's study, because of issues of scale, and submitted a 
draft copy of a paper in support of their position.
    Service Response: Although the metapopulation structure of the 
Peninsular bighorn sheep was not specifically mentioned in the proposed 
rule, the importance of maintaining connectivity within the range was 
stressed. In this regard, the potential impacts of isolation (e.g., 
inbreeding) were discussed.
    The Service agrees that the factors affecting the populations 
Berger (1990) studied are not necessarily the same factors affecting 
the Peninsular bighorn sheep. However, the Service did not state the 
factors were the same in the proposed rule, but, referenced the 
conclusion of Berger (1990) that populations containing less than 50 
bighorn sheep became extinct within 50 years. Again, the discussion on 
this issue in the proposed rule focused on the potential problems of 
isolation. Regardless of the metapopulation structure of Peninsular 
bighorn sheep, isolation compromises long-term viability. The Service 
finds no basis to support the statement that Berger's (1990) results 
were speculative. Berger's (1990) results appear to have been based on 
observed (reported) population numbers of several populations of 
bighorn sheep over an extended period of time. The Service concurs that 
the scale of a study can affect the results and ensuing 
interpretations. However, the issues facing the Peninsular bighorn 
sheep include fragmentation of habitat and the isolation of ewe groups. 
It is well known that small isolated groups are subject to a variety of 
genetic problems (Lacy 1997).
    Issue 9: One commenter recommended the Service address the 
introduction and spread of disease due to equestrian use in Peninsular 
bighorn sheep habitat.
    Service Response: The Service is unaware of any data that support 
the notion that disease transmission occurs between horses and bighorn 
sheep. If such information becomes available, this issue will be taken 
into consideration during the development and implementation of a 
recovery plan.
    Issue 10: A commenter indicated the Service generally described the 
habitat of the Peninsular bighorn sheep in the proposed rule but did 
not specifically mention the habitat conditions that exist in the Santa 
Rosa Mountains or any other Peninsular Range. Furthermore, without this 
information, no specific management strategies can be formulated to 
protect the species.
    Service Response: The Service agrees that specific management 
strategies will have to be based on more detailed ecological data. The 
CDFG has been sponsoring studies that will generate data needed to 
determine conservation requirements for the survival and recovery of 
the Peninsular bighorn sheep. The draft Peninsular Ranges Coordinated 
Bighorn Sheep Metapopulation Management Plan (BLM et al. 1993) 
describes the Peninsular Ranges' ecosystems and delineates Peninsular 
bighorn sheep historic, core, lambing, and movement habitat. These data 
will be used to develop conservation and recovery strategies.
    Issue 11: One commenter pointed out that neither burros nor 
javelina (collared peccary) occur in the California Peninsular Ranges. 
Therefore, these species could not compete with the Peninsular bighorn 
sheep for food.
    Service Response: The Service concurs. Javelina (collared peccary) 
and burros were mentioned in the proposed rule in an opening background 
paragraph describing potential competitors of bighorn sheep. The 
Service did not intend to suggest that javelina specifically competed 
with Peninsular bighorn sheep. Although not an issue for Peninsular 
bighorn sheep in the United States, burros have been documented in 
bighorn sheep habitat in Baja California, Mexico (DeForge et al., 
1993).
    Issue 12: One commenter stated that the depleted status of 
Peninsular bighorn sheep was due more to mountain lion predation, 
conflicts with autos, and low population numbers than from impacts 
related to the construction and operation of golf courses.
    Service Response: The decline of the Peninsular bighorn sheep is 
attributable to a number of factors that, in combination, are 
threatening the survival of this distinct population

[[Page 13140]]

segment. See the Summary of Factors Affecting the Species section for 
further discussion.
    Issue 13: Several commenters observed that many of the conclusions 
presented in the proposed rule appear to be based on information 
provided by the Bighorn Institute.
    Service Response: In accordance with the Act and its implementing 
regulations, the Service has used the best scientific and commercial 
data available in assessing the status of the Peninsular bighorn sheep 
and making the final listing determination. The Service obtained 
information from various sources including the CDFG, CDPR, the Desert 
Bighorn Council, published articles from scientific journals, and the 
Bighorn Institute.
    Issue 14: One commenter disagreed with the suggestion in the 
proposed rule that depressed recruitment was probably linked to disease 
throughout most of the Peninsular bighorn sheep's range. The commenter 
went on to state that exposure to disease did not demonstrate a 
population was declining because bighorn sheep populations commonly are 
exposed to disease organisms. The commenter also recommended that 
listing be delayed until further research could determine the different 
factors affecting the Peninsular bighorn sheep and its decline.
    Service Response: The proposed rule indicated that depressed 
recruitment probably was linked to a disease epizootic. This was the 
most reasonable conclusion at that time based on available information 
regarding the effects of disease in the Santa Rosa Mountains and the 
general decline in the number of Peninsular bighorn sheep. The presence 
of recurrent disease remains a likely cause for the overall continuing 
decline of Peninsular bighorn sheep numbers. However, disease is not 
the only factor negatively affecting this species. The Peninsular 
bighorn sheep in the United States has declined by at least 76 percent 
since 1971. Another factor, in addition to disease, that has 
contributed to low recruitment is an increase in predation rates (W. 
Boyce and E. Rubin, in litt. 1997). The final rule indicates that 
exposure to diseases such as blue tongue occurs in a significant 
portion of the Peninsular bighorn sheep's range. Any delay in listing 
this distinct population segment to await the results of research on 
the interaction of the various threats could result in postponement of 
implementation of conservation and recovery measures, thus, 
contributing further to the Peninsular bighorn sheep's decline. See 
Factor C in the Summary of Factors Affecting the Species Section for a 
discussion of this topic.
    Issue 15: One commenter stated that the effects of cattle grazing 
on wild sheep needed to be re-examined because the pathogen Pasteurella 
is not transmitted by cattle, but by domestic sheep. Another commenter 
stated that Pasteurella had not been a problem for the Peninsular 
bighorn sheep and was, therefore, not relevant to the listing.
    Service Response: The Service's concerns about cattle grazing 
relative to the conservation of Peninsular bighorn sheep is prompted by 
the potential of cattle to harbor pathogens such as PI-3 and blue 
tongue. Both of these viruses have likely contributed to Peninsular 
bighorn sheep mortality. In addition, Pasteurella sp. also infect mule 
deer and there is overlap in the range of mule deer, domestic sheep, 
and Peninsular bighorn sheep. Although the Service is unaware of 
Pasteurella sp. infections in Peninsular bighorn sheep, domestic sheep 
use areas adjacent to San Jacinto Mountain and could be a source for 
this infection.
    Issue 16: One commenter stated that data are inadequate to 
demonstrate an increase in predation, and the potential effect of this 
threat on Peninsular bighorn sheep had not been assessed in the defined 
range.
    Service Response: The Service concurs that predation and its effect 
on Peninsular bighorn sheep has not been conclusively assessed. 
However, an increase in predation in the northern Santa Rosa Mountains 
had been noted. Since publication of the proposed rule, further 
indication of an increase in predation due to mountain lions has been 
documented (W. Boyce and E. Rubin, in litt. 1997)
    Issue 17: Several commenters expressed concern about the use of 
current information and recommended the Service use information that is 
unbiased and peer-reviewed. One commenter questioned how a listing 
decision could be rendered when information is unavailable for review 
or has not undergone the scrutiny of impartial analysis. This commenter 
made specific reference to work being conducted by Oliver Ryder, Ph.D. 
of CRES, on Weems bighorn sheep.
    Service Response: As required, the Service used the best available 
scientific and commercial information for the final listing decision 
and all such information was accessible for public review and analysis. 
However, only information related to Peninsular bighorn sheep ecology 
or otherwise relevant to determining whether listing this distinct 
population segment was warranted was the subject of this review. 
Moreover, peer review of the listing proposal by three appropriate and 
independent specialists was solicited to ensure the best biological and 
commercial information was used.
    Issue 18: Several commenters suggested that development within and 
adjacent to Peninsular bighorn sheep habitat was not detrimental and 
that the Service should focus on other causes of the decline, such as 
grazing of cattle in bighorn sheep habitat. One of the commenters 
stated that current mitigation measures needed to be compiled and 
analyzed to determine if listing of the Peninsular bighorn sheep was 
warranted.
    Service Response: Populations of Peninsular bighorn sheep located 
adjacent to urban development, such as golf courses and suburban 
housing areas, are known to modify their behavior in non-adaptive ways. 
For example, abnormally high concentrations of ewes, rams, and lambs 
regularly forage and water at such developments in the Rancho Mirage 
area of California throughout all months of the year (DeForge and 
Osterman, pers. comm., 1997).
    This altered behavior has exposed the northern Santa Rosa Mountains 
ewe group to several unnatural conditions leading to relatively high 
levels of mortality (DeForge 1997): excessive exposure to high levels 
of fecal material increasing the chance for the spread of disease; 
excessive use of an unnaturally moist environment suitable for 
harboring infectious disease and parasites; unusually high levels of 
adult mortality associated with predation; exposure to non-native and 
potentially toxic plants; short-term lamb abandonment leading to 
increased risk of lamb predation; and loss of ewe group ``memory'' of 
other available water and forage areas in their historic home range 
(Rubin, Ostermann, and DeForge, pers. comm., 1997). See Factors C and E 
for further discussion of these issues.
    Issue 19: One commenter stated that the Service had not monitored 
or considered the population numbers of bighorn sheep in some mountain 
ranges, such as the Little San Bernardino and Chocolate mountains.
    Service Response: The bighorn sheep occurring in the Little San 
Bernardino and Chocolate mountains are not a component of the distinct 
vertebrate population segment under consideration in this final listing 
rule. Besides the geographic separation, recent genetic research (Boyce 
et al. 1997) concluded the Peninsular bighorn sheep population ``formed 
a discrete group

[[Page 13141]]

with relatively high gene flow,'' whereas, the genetic distance between 
three nearby Mojave populations of desert sheep including the bighorn 
sheep occurring in the Little San Bernardino and Chocolate mountains 
was more than three times greater. That is, the genetic distance 
between the Peninsular bighorn sheep and their nearest neighbors 
supports the conclusion that the Peninsular group is discrete and meets 
the definition of a distinct vertebrate population segment.
    Issue 20: One commenter stated there is no evidence to support the 
conclusion that hikers are contributing to the decline of Peninsular 
bighorn sheep.
    Service Response: Peninsular bighorn sheep are sensitive to human 
disturbance during critical periods, such as lambing. For example, 
hikers detrimentally affect survival and recovery of this species when 
this activity is in proximity to lambing areas and bighorn sheep 
abandon these areas. Additional impacts occur when human activity 
hinders the access of Peninsular bighorn sheep to water during times of 
stress. MacArthur et al. (1979) documented a 20 percent rise in mean 
heart rate when bighorn sheep were continuously exposed to people. 
Another study found that areas experiencing more than 500 visitor-days 
of use per year resulted in a decline of use by bighorn sheep (Graham 
1971 in Purdy and Shaw 1980).
    Issue 21: Several commenters stated that the bighorn sheep decline 
could have been avoided. The Service should have been proactive and 
worked with local land use planning agencies by providing guidance 
concerning potential project-related impacts on Peninsular bighorn 
sheep. In addition, one of the commenters recommended that 
communication between land-use planning agencies and the Service 
commence immediately and that private, State, and Federal parties be 
treated equitably in the conservation process.
    Service Response: The Service has long been involved with local 
planning agencies within the range of the Peninsular bighorn sheep as a 
technical adviser. Recommendations of the Service have not always been 
incorporated into project design and location resulting in 
irretrievable impacts (see Response to Issue 18). The Service concurs 
that all involved parties should be treated equitably during future 
efforts to conserve and recover the species.
    Issue 22: One commenter stated that the grazing of cattle on 
Federal lands should be terminated where the activity may impact 
Peninsular bighorn sheep. The commenter also stated that movement 
corridors should be conserved.
    Service Response: The Service contends that activities impacting 
Peninsular bighorn sheep should be avoided to the extent possible and 
endorses the conservation of movement corridors. Upon the listing of 
the Peninsular bighorn sheep, the issue of cattle grazing and movement 
corridors will be evaluated, and appropriate actions to be taken will 
be identified as part of the species conservation and recovery process.
    Issue 23: One commenter stated that the Peninsular bighorn sheep 
would benefit from the addition of golf courses.
    Service Response: The Service is unaware of scientific information 
demonstrating that golf courses are beneficial to the long-term 
survival and recovery of Peninsular bighorn sheep. There is evidence 
that golf courses negatively impact Peninsular bighorn sheep through 
the spread of parasites (e.g., hookworms) and availability of toxic 
plants such as oleander. Furthermore, golf courses do not provide ideal 
forage for this species and the associated human activity disrupts the 
normal behavioral patterns of bighorn sheep (see Response to Issue 18).
    Issue 24: One commenter recommended that the Peninsular bighorn 
sheep be relocated where interaction with people would be less likely 
to occur.
    Service Response: The Peninsular bighorn sheep have specific 
habitat requirements within the Peninsular Mountain Ranges of southern 
California. The removal of an animal from its native habitat to another 
location provides no assurance of survival. For listed species, such 
removal and relocation would have to meet recovery and conservation 
objectives to be consistent with purposes of the Act.
    Issue 25: Several commenters suggested it was unlikely that Federal 
listing of this population would result in protection beyond that 
already provided by the California Environmental Quality Act (CEQA) and 
CESA. In addition, the commenters predicted that Federal listing may be 
detrimental by making the approval process for bighorn sheep 
reintroductions or management actions more complex.
    Service Response: Federal listing of the Peninsular bighorn sheep 
will complement the protection options available under State law 
through measures discussed below in the ``Available Conservation 
Measures'' section. The Service will use established procedures to 
evaluate management actions necessary to achieve recovery of the 
species and thereby avoid any undue implementation delays. In addition, 
Federal listing would provide additional resources for the conservation 
of the species through sections 6 and 8 of the Act.
    Issue 26: Several commenters stated that listing of the Peninsular 
bighorn sheep was unnecessary because effective voluntary efforts exist 
for safeguarding this species at no public cost. Furthermore, the 
existing population occurs almost exclusively on lands administered by 
State or Federal agencies on which private actions will not occur.
    Service Response: Voluntary efforts are important to conservation 
of Peninsular bighorn sheep, but, to date, these efforts have not 
stabilized or reversed the numerical decline. The effects of urban and 
commercial development, disease, and predation continue to represent 
foreseeable threats to this distinct population segment. The inadequacy 
of existing regulatory mechanisms to stabilize or reverse the decline 
is discussed in Factor D.
    Issue 27: Several commenters stated that the Service has ignored 
existing efforts to conserve the Peninsular bighorn sheep. In addition, 
one of these commenters recommends the Service consider the 
metapopulation approach to the management of wild sheep in California. 
This same commenter explained that the Peninsular Ranges population of 
bighorn sheep probably represents one of the most intact 
metapopulations of this species from the standpoint of demography and 
corridors connecting demes.
    Service Response: Several State and Federal management plans have 
been prepared for bighorn sheep. However, these plans have not 
effectively reversed the decline of the Peninsular bighorn sheep 
population. Federal listing will complement and add to these 
conservation efforts. Existing management plans and the population 
ecology of the Peninsular bighorn sheep will be important components in 
the development of a recovery plan.
    Issue 28: One commenter discussed the history of bighorn sheep 
management in Mexico and indicated that it had been ineffective in the 
past. The commenter also stated that the current program has inadequate 
resources for addressing threats on bighorn sheep such as poaching, 
disease exposure, and habitat loss from feral livestock. The commenter 
concluded that listing of the Peninsular bighorn sheep may 
substantially contribute to

[[Page 13142]]

the conservation and recovery of these animals.
    Service Response: Based on information received during the last 
comment period extension, the Mexican Government established a new 
conservation program in April 1997 for bighorn sheep in Baja 
California, Mexico. Given that there are significantly more bighorn 
sheep in Baja California, Mexico, as compared to southern California, 
there is more time to ascertain the effectiveness of the conservation 
program and the status of Peninsular bighorn sheep in this area. If the 
population of Peninsular bighorn sheep decline under the Mexican 
Government's conservation program, future listing of the animals may be 
appropriate.
    Issue 29: One commenter stated that Mexican authorities had not 
been properly consulted and these authorities did not support listing.
    Service Response: As required, the Service corresponded on February 
21, 1992, and June 8, 1992, with the Mexican government when the 
Peninsular bighorn sheep was proposed for listing. Moreover, the 
Service reopened the public comment period on October 27, 1997, for an 
additional 15 days to acquire additional information on the status, 
distribution, and management of bighorn sheep in Baja California, 
Mexico. Comments were received from the Mexican government during this 
third, and last, comment period extension and were considered in making 
the final listing determination.
    Issue 30: One commenter stated the Service that the purpose of the 
Act was to conserve wild species. The commenter stated that the 
proximity of the Bighorn Institute to private development was, 
therefore, not a legitimate justification for proposing the species as 
endangered.
    Service Response: The Service concurs with the commenter about 
conservation of species in the wild (i.e., ``conserve wild species''). 
The Bighorn Institute and Living Desert Museum maintain captive 
populations of Peninsular bighorn sheep for scientific and educational 
purposes. This use is thought to have no negative impact on free-
ranging bighorn. However, the fact that the Bighorn Institute is 
located close to residential/commercial development was mentioned in 
the proposed rule as an indirect factor affecting Peninsular bighorn 
sheep.
    Issue 31: Several commenters criticized the Service for not 
addressing the economic impacts of listing the Peninsular bighorn sheep 
population as endangered. One of these commenters stated that the 
Peninsular bighorn sheep should not be listed if it would stifle 
economic development.
    Service Response: In accordance with 16 U.S.C. Sec. 1533(b)(1)(A) 
and 50 CFR 424.11(b), listing decisions are made solely on the basis of 
the best scientific and commercial data available. In adding the word 
``solely'' to the statutory criteria for listing a species, Congress 
specifically addressed this issue in the 1982 amendments to the Act. 
The legislative history of the 1982 amendments states: ``The addition 
of the word ``solely'' is intended to remove from the process of the 
listing or delisting of species any factor not related to the 
biological status of the species. The Committee strongly believes that 
economic considerations have no relevance to determinations regarding 
the status of species and intends that the economic considerations have 
no relevance to determinations regarding the species' status.
    Issue 32: One commenter indicated that a 30 day comment period for 
the listing proposal was inadequate and the continued processing of the 
proposed rule was prohibited by the Act.
    Service Response: The Service has provided ample opportunity for 
public comment during this rule making process. The initial comment 
period for the proposed rule was open for 6 months. The Service 
reopened the comment period for an additional 30 days on April 7, 1997 
(62 FR 16518), for an additional 15 days on June 17, 1997 (62 FR 
32733), and then again for an additional 15 days on October 27, 1997 
(62 FR 55564). See discussion under Previous Federal Action for added 
details.
    Issue 33: One commenter stated that the Peninsular bighorn sheep 
should not be listed because once listed it becomes impossible to 
remove species from the list, and expressed concern regarding the 
closure of mountain areas to recreationists.
    Service Response: A principal goal of the Service for listed 
species is to recover species to a point at which protection under the 
Act is no longer required. When the recovery goals for a species have 
been met, the Service may prepare a proposal to delist or reclassify 
the species based on the best available scientific and commercial 
information. The process for delisting or reclassifying a species, per 
section 4(b)(3)(A) of the Act, is similar to that used for listing. 
Regarding closure of mountain areas to recreationists, certain 
locations of special sensitivity, such as lambing areas, may be closed 
to prevent disturbance and promote the recovery of the Peninsular 
bighorn sheep. Most other recreational use restrictions would be 
unchanged.
    Issue 34: One commenter recommended that the Service designate 
critical habitat concurrently with the listing of the Peninsular 
bighorn sheep. A second commenter disagreed with the Service's 
rationale for not proposing critical habitat but made no recommendation 
concerning the designation of critical habitat. Another commenter 
indicated that designation of critical habitat would not lead to 
increased poaching of the Peninsular bighorn sheep because of State 
listing and protection regulations. Commenters also stated that the 
discussions under the Critical Habitat and Available Conservation 
Measures sections in the proposed rule were contradictory.
    Service Response: The Service has determined that designation of 
critical habitat would increase the threat of human activities to 
Peninsular bighorn sheep and that such a designation would not be 
beneficial to the species. The identification of such areas on critical 
habitat maps would likely call attention to the locations of bighorn 
sheep (especially lambing areas) and increase the degree of threat from 
human intrusion. Moreover, protection of habitat and other conservation 
actions are better addressed through recovery planning and section 7 
consultation processes.
    The discussions under Critical Habitat and Available Conservation 
Measures are not contradictory with respect to section 7. The Available 
Conservation Measures section addresses the conservation actions that 
result from listing. With or without critical habitat, Federal agencies 
are required to consult with the Service if an action may affect a 
listed species. Critical habitat is mentioned under Available 
Conservation Measures because regulations pertaining to section 7(a), 
7(a)(2) and 7(a)(4) are reiterated. The responsibility of Federal 
agencies is discussed in general, and not in terms specifically related 
to the Peninsular bighorn sheep. For further discussion of this issue 
see the Critical Habitat section.

Summary of Factors Affecting the Species

    After a thorough review and consideration of all information 
available, the Service has determined that the Peninsular bighorn sheep 
should be classified as an endangered distinct population segment. 
Procedures found at section 4 of the Act and regulations (50 CFR part 
424) promulgated to implement the listing

[[Page 13143]]

provisions of the Act set forth the procedures for adding species to 
the Federal Lists. A species may be determined to be endangered or 
threatened due to one or more of the five factors described in section 
4(a)(1). These factors and their application to the Peninsular bighorn 
sheep distinct population segment (Ovis canadensis) are as follows:
    A. The present or threatened destruction, modification, or 
curtailment of its habitat or range. Peninsular bighorn sheep have been 
extirpated from several historic locations, including the Fish Creek 
Mountains (Imperial County) and the Sawtooth Range (San Diego County) 
(DeForge et al., 1993). In the United States, the number of Peninsular 
bighorn sheep has declined from an estimated 1,171 individuals in 1971 
to about 280 individuals in 1997 (DeForge et al. 1995; J. DeForge, in 
litt. 1997; E. Rubin and W. Boyce, in litt. 1996; W. Boyce and E. 
Rubin, in litt, 1997). Habitat loss (especially canyon bottoms), 
degradation, and fragmentation associated with the proliferation of 
residential and commercial development, roads and highways, water 
projects, and vehicular and pedestrian recreational uses are threats 
contributing to the decline of Peninsular bighorn sheep throughout its 
range.
    Peninsular bighorn sheep are susceptible to fragmentation due to 
the distribution of habitat (narrow band at low elevation), use of 
habitat (e.g., occupying low elevations), and population structure. 
Restricted to elevations below the distribution of chaparral habitat 
(typically about 1,050 m (3,500 ft)), encroaching urban development and 
human related disturbance have the dual effect of restricting remaining 
animals to a smaller area and severing connections between ewe groups. 
The Peninsular bighorn sheep distinct population segment, like other 
bighorn sheep populations, is composed of ewe groups that inhabit 
traditional areas (cluster of canyons) and rams that move among these 
groups exchanging genetic material. Maintenance of genetic diversity 
allows small ewe groups to persist. The inability of rams and 
occasional ewes to move between groups erodes the genetic fitness of 
isolated groups. Urban and commercial development may ultimately 
fragment the metapopulation into isolated groups too small to maintain 
long-term viability, as apparently was the case in the extirpation of 
one ewe group in the United States in the recent past.
    Urban development and associated increases in human activities in 
bighorn sheep habitat were reported to be the leading cause of 
extinction of an entire bighorn sheep population (ewes, rams, and 
lambs) in Tucson, Arizona (Krausman, pers. comm. 1997). In the River 
Mountains, Nevada, 9 of 17 marked desert bighorn sheep ewes altered 
their normal watering patterns; seven of these ewes abandoned the site 
(Leslie and Douglas 1980). Leslie and Douglas (1980) noted that, 
because ewes are more restricted in their movements and display a 
relatively high degree of fidelity to water sources, such abrupt 
changes in watering patterns are probably the result of extrinsic 
disturbances. Development has resulted in habitat abandonment in other 
bighorn sheep populations (Ferrier 1974). Other researchers have 
maintained that recreational encroachment can be most damaging during 
critical periods of the year for bighorn sheep, such as lambing (Geist 
1971, Light 1973, Cowan 1974).
    Abandonment of preferred habitat is anticipated to be detrimental 
to the long-term survival of Peninsular bighorn sheep. Abandonment of a 
lambing area in the Peninsular Ranges has been reported, and it has 
been attributed to human activities. The construction of a flood 
control project took place in Magnesia Canyon within the City of Rancho 
Mirage in 1982. This construction took place below a lambing area that 
was occupied by the northern Santa Rosa Mountains (SRM) ewe group. 
During the construction of the flood control project, the northern SRM 
ewe group relocated their lambing area from Bradly Peak (above Magnesia 
Canyon, and in direct line of site to the flood control project area) 
to Ramon Peak (DeForge, pers. comm., 1997). The distance between these 
two lambing areas is estimated at about 2.4 km (1.5 mi). Ramon Peak is 
situated away from areas occupied by humans, and human activities were 
correspondingly absent compared to Magnesia Canyon during construction. 
This relocation corresponded to the shift in habitat use and 
abandonment of some areas affected by the noise and view of humans 
during construction observed by DeForge and Scott (1982). DeForge and 
Scott (1982) also observed a marked difference in behavior when ewes 
with lambs used a watering area located 200 to 500 m (660 to 1650 ft) 
from the construction area. As further evidence that the abandonment of 
the lambing area was attributable to human activities, DeForge (pers. 
comm., 1997) also indicated that the ewe group re-occupied the Bradly 
Peak lambing area the following year after construction and human 
activities subsided. Approved and future projects such as Shadowrock 
Golf Course and Mountain Falls Golf Course, respectively, may result in 
the abandonment of the main remaining lambing area in the San Jacinto 
Mountains.
    The Coachella Valley Association of Governments anticipates that by 
the year 2010 the human population there will increase from 227,000 to 
over 497,000, not including 165,000 to 200,000 seasonal residents. In 
1989, the population of Imperial County was 116,000. The cities of El 
Centro, Imperial, and Calexico grew by about one-third between 1980 and 
1989 (Bureau of Reclamation 1991). Increased human populations and 
associated commercial and residential development will likely continue 
to increase destruction of habitat and disrupt sheep behavioral 
patterns.
    B. Overutilization for commercial, recreational, scientific, or 
educational purposes. There is no open hunting season for Peninsular 
bighorn sheep in the United States. Although the limited opportunities 
for desert bighorn hunting in California create a temptation for taking 
without a license, poaching does not appear to be a problem at this 
time.
    The Bighorn Institute and Living Desert Museum maintain captive 
populations of Peninsular bighorn sheep for scientific and educational 
purposes. This use is thought to have no negative impact on free-
ranging bighorn.
    C. Disease or predation. Disease is a major factor responsible for 
the precipitous decline of Peninsular bighorn sheep in the northern 
Santa Rosa Mountains and appears to significantly contribute to 
population declines elsewhere throughout its range. Elliott et al. 
(1994) found a higher level of exposure to viral and bacterial 
pathogens in the Peninsular bighorn sheep population than in other 
California bighorn sheep populations. Past higher exposure to pathogens 
suggests that disease may have been a major contributing factor in this 
distinct population segment's decline.
    Bighorn sheep are susceptible to a variety of bacterial, fungal, 
and viral infections (DeForge et al. 1982, Turner and Payson 1982, 
Clark et al. 1985). Lambs and older sheep may be most susceptible to 
disease. Numerous endoparasites and ectoparasites are known to occur in 
this species (Russi and Monroe 1976, Lopez-Fonseca 1979). The 
relationship between disease, its transmission, and factors such as 
stress, density, competition, water availability, and disturbance are 
not well understood. Disease manifestation

[[Page 13144]]

probably occurs during stressful periods such as high or low population 
levels, reproductive activity, low nutrient availability, and climatic 
extremes (Taylor 1976, Turner and Payson 1982).
    Disease is responsible for high lamb mortality rates in Peninsular 
bighorn sheep (Sanchez et al. 1988). In the northern Santa Rosa 
Mountains, excessive lamb mortality has occurred since 1977 (DeForge et 
al. 1995). DeForge et al. (1982) reported evidence that bighorn sheep 
lamb mortality in the Santa Rosa Mountains was due to pneumonia. 
Bacterial pneumonia is usually a sign of weakness caused by another 
agent such as a virus, parasite, or environmental stress that lowers an 
animal's resistance to disease. DeForge and Scott (1982) reported 
serological evidence that a combination of parainfluenza-3 (PI-3), blue 
tongue (BT), epizootic hemorrhagic disease (EHD), and contagious 
ecthyma (CE) viruses may be contributing initiating factors for the 
development of pneumonia in the Santa Rosa Mountains ewe group. In 
addition to exposure to the above mentioned diseases, antibody titers 
to respiratory syncytial virus (RSV) have been found in Peninsular 
bighorn sheep (Clark et al. 1985). Poor nutrition, predation, climatic 
changes, and human related impacts may contribute to high lamb 
mortality. Vaccination experiments have been conducted for BT and PI-3. 
Vaccines for PI-3 have been used with limited success in captive and 
wild sheep (Jessup et al. 1990).
    Domestic and feral cattle can act as disease reservoirs. Several 
viruses discovered in sick bighorn sheep lambs were non-native and 
thought to be introduced by domestic livestock (DeForge, in litt. 
1988). However, the potential role of livestock in disease transmission 
is not well understood. Staff of the Anza-Borrego Desert State Park 
(Park) completed a project to remove 119 feral cattle from the Park in 
1990. Six types of viruses were detected in these cattle. Blood samples 
taken from cattle grazing in allotments adjacent to Peninsular bighorn 
sheep habitat within the Park have contained several viruses. 
Peninsular bighorn sheep in Mexico have also tested positive to 
exposure to viral and bacterial diseases (J. DeForge, pers. comm., 
1997).
    Other livestock may transmit diseases as well. Domestic sheep 
harbor bacteria (Pasteurella sp.) and viruses such as BT that can kill 
bighorn sheep, and close contact results in transmission to and the 
subsequent death of most or all of the exposed animals (Foreyt and 
Jessup 1982). Although no grazing allotments for domestic sheep have 
been issued by BLM or USFS in the Peninsular Ranges, the potential for 
their presence exists. Domestic sheep associated with commercial 
operations have been observed in the San Jacinto River along the 
northern edge of the San Jacinto Mountains. In addition, small numbers 
of domestic sheep are raised by private individuals living along the 
northern edge of the San Jacinto Mountains (A. Davenport, Fish and 
Wildlife Service, pers. obs. 1993).
    Cattle or domestic sheep do not have to occupy Peninsular bighorn 
sheep habitat for disease transmission to occur. For example, Jessup et 
al. (1985) has found antibodies for this pathogen in mule deer. Blue 
tongue, a disease transmitted by a biting midge (Culicoides sp.), 
occurs in animals such as cattle, sheep, goats, mule deer, and bighorn 
sheep. Cattle appear to be capable of harboring the virus (Wallmo 1981, 
Jessup 1985, Jessup et al. 1990). Overlap in habitat use by Peninsular 
bighorn sheep, southern mule deer, and the biting midge may provide a 
pathway for disease transmission from deer populations associated with 
livestock to bighorn sheep. This pathway may involve either movement of 
an infected individual or the progression of an epizootic through the 
general deer population to Peninsular bighorn sheep where the two 
species overlap.
    Based on available information, and given the susceptibility of 
bighorn sheep to introduced pathogens, disease will continue to pose a 
significant and underlying threat to the survival of Peninsular bighorn 
sheep. This situation is exacerbated by the presence of cattle and 
other livestock in and adjacent to areas occupied by Peninsular bighorn 
sheep.
    Urban developments such as golf courses and associated housing 
areas also influence the effect of disease and predation on the 
Peninsular bighorn sheep. For example, high concentrations of ewes, 
rams, and lambs regularly forage and water at such developments in the 
Rancho Mirage area of California throughout all months of the year 
(DeForge and Osterman, pers. comm., 1997).
    This behavior has exposed the northern Santa Rosa Mountains ewe 
group to several unnatural conditions leading to relatively high levels 
of mortality (DeForge 1997): excessive exposure to high levels of fecal 
material increasing the chance for the spread of disease; excessive use 
of an unnaturally moist environment suitable for harboring infectious 
disease and parasites; unusually high levels of adult mortality 
associated with predation; exposure to non-native and potentially toxic 
plants; short-term lamb abandonment leading to increased risk of lamb 
predation; and loss of ewe group ``memory'' of other available water 
and forage areas in their historic home range (Rubin, Osterman, and 
DeForge, pers. comm., 1997).
    DeForge and Ostermann (in prep.) reported that urbanization was the 
leading known cause of death to Peninsular bighorn sheep occupying the 
northern Santa Rosa Mountains. During their investigation in the 
northern Santa Rosa Mountains, urbanization accounted for 34.2 percent 
of all recorded adult mortalities. Mortalities directly caused by 
urbanization were associated with ingestion of toxic, non-native 
plants, automobile collisions, and fences. Indirect causes of death 
associated with urbanization included parasite infestations and altered 
habitat use.
    Exposure to high concentrations of feces can lead to unnaturally 
high levels of exposure to disease and parasites (Georgi 1969), and may 
contribute to Peninsular bighorn sheep population declines. Development 
in and adjacent to the Santa Rosa Mountains has established irrigated 
grass lawns, golf courses, and ponded waters providing environmentally 
suitable conditions for the strongyle parasite to successfully complete 
its life cycle, and increase its presence in a naturally arid 
environment. Sheep can be exposed to the strongyle parasite from the 
feces of an infected individual (Georgi 1969). Strongyle parasites have 
been reported in the northern Santa Rosa Mountains ewe group (DeForge 
and Osterman 1997). Animals exhibiting symptoms from the infection of a 
strongyle parasite are less active, forage less, tend to stay unusually 
close to water sources, become weak, are extremely emaciated, and 
exhibit anemia (Georgi 1969). Mortality from infection of the strongyle 
parasite may be experienced in sheep, particularly under situations 
that create additional stress (Georgi 1969).
    Strongyle parasites are common in domestic ruminant, horse, and pig 
hosts, and require moist environments for the survival of its larval 
stages outside of the host. The strongyle parasite life cycle cannot be 
completed in arid environments, and strongyle infestations are 
generally rare in desert regions (Georgi 1969). However, between 1991 
and 1996, more than 85 percent of the Peninsular bighorn sheep sampled 
in the Santa Rosa Mountains ewe group were infected with the strongyle 
parasite (DeForge and Osterman, unpubl. data). Ewes, rams, and lambs 
are susceptible to infection

[[Page 13145]]

with the strongyle parasite. Clinical signs of strongyle parasites in 
the Peninsular bighorn sheep have been reported only from the Santa 
Rosa Mountains ewe groups. Strongyle parasites have not been detected 
in the San Jacinto Mountains (SJM) ewe groups, and are considered rare 
or absent in other ewe groups.
    Peninsular bighorn sheep exhibiting physiological stress related to 
an infestation of the strongyle parasite are at greater risk of 
predation, and less likely to successfully reproduce. Presently, there 
is no local or regional program to inoculate Peninsular bighorn sheep 
against non-native, introduced diseases, viruses, and parasites.
    The reduction of disease outbreaks centers, in large part, on 
reducing factors that stress Peninsular bighorn sheep. Stress 
predisposes animals to disease (DeForge 1976). One of the major factors 
that stress bighorn sheep is human encroachment into their habitat. The 
decline of the Peninsular bighorn sheep is markedly steeper where the 
population borders the developing areas of the Coachella Valley. The 
decline in the population adjacent to urban areas in the Coachella 
Valley has been 35 percent greater than that occurring in Anza Borrego 
Desert State Park. Disease has been documented as an important factor 
in the decline of the population in the northern Santa Rosa Mountains 
(DeForge and Scott 1982, DeForge et al. 1982). Although the pathogens 
responsible for the diseases in the Santa Rosa Mountains have also been 
detected in Anza Borrego Desert State Park (Elliott et al. 1994), the 
population in Anza Borrego Desert State Park has declined at a slower 
rate (57 percent versus 92 percent).
    Increased risk of predation has also been attributed to unnatural 
environments found at the urban interface. DeForge (pers. comm., 1997) 
has observed higher numbers of adult Peninsular bighorn sheep 
mortalities caused by mountain lions (Felis concolor) closer to the 
urban environment as compared to wild lands. Domestic dogs often occur 
along the urban-wild lands interface, and are also capable of injuring 
and killing lambs, ewes, and young or unhealthy rams. Encroaching 
development not only increases the abundance of domestic dogs along the 
urban-wild lands interface, but also creates unnatural landscape 
characteristics such as hedge rows, dense patches of tall vegetation, 
and other unnatural cover suitable for predators to hide and ambush 
potential prey. The Service has received complaints from residents of 
Thunderbird Cove that the presence of Peninsular bighorn sheep feeding 
on lawns attracts mountain lions, which some of the residents have 
observed.
    Natural predation is not known to be a limiting factor in free-
roaming desert bighorn sheep populations having adequate escape cover 
(Blaisdell 1961, Elliot 1961, and Weaver 1961). According to Wilson 
(1980), predation, as a mortality factor, decreases in significance as 
the size of a population increases. In addition, major predation 
problems have occurred with populations occupying restricted home 
ranges or fenced areas (Cooper 1974, Kilpatrick 1975). Compared to the 
northern Santa Rosa Mountains ewe group, ewe groups to the south, the 
majority of which do not occupy restricted home ranges, have 
experienced high rates of natural predation compared to urban-related 
mortalities (Boyce 1995). Ewe group sizes in these areas are larger 
than the northern Santa Rosa Mountains and San Jacinto Mountains ewe 
groups, and can likely tolerate such predation levels.
    Coyote (Canis latrans), bobcat (Lynx rufus), mountain lion, gray 
fox (Urocyon cinereoargenteus), golden eagle (Aquila chryseatos), and 
free-roaming domestic dogs prey upon bighorn sheep. Predation generally 
has an insignificant effect except on small populations. In recent 
years, mountain lion predation of Peninsular bighorn sheep appears to 
have increased in the northern Santa Rosa Mountains (J. DeForge, pers. 
comm., 1991, W. Boyce and E. Rubin, in litt. 1997) and sheep encounters 
with domestic dogs are likely to increase with more urban development. 
The deaths of several radio-collared Peninsular bighorn sheep in Anza 
Borrego State Park have been attributed to mountain lions (W. Boyce and 
E. Rubin, in litt. 1997).
    D. The inadequacy of existing regulatory mechanisms. The Peninsular 
bighorn sheep has been listed as threatened by the State of California 
since 1971 (CDFG 1991). Pursuant to the California Fish and Game Code 
and the CESA, it is unlawful to import or export, take, possess, 
purchase, or sell any species or part or product of any species listed 
as endangered or threatened. Permits may be authorized for certain 
scientific, educational, or management purposes. The CESA requires that 
State agencies consult with the CDFG to ensure that actions carried out 
are not likely to jeopardize the continued existence of listed species. 
However, most of the activities occurring within the range of the 
Peninsular bighorn sheep are not State authorized, funded, or 
permitted, resulting in few consultations under the CESA.
    Shadowrock Golf Course and Altamira represent examples of locally 
approved projects that could have significant adverse effects on the 
Peninsular bighorn sheep. The City of Palm Springs approved the 
Shadowrock project which would eliminate important canyon bottom 
habitat and compromise or curtail sheep movement corridors. In 
addition, a settlement agreement between the developer of Shadowrock 
and the CDFG allows the project to proceed with only minor changes from 
the original design. Similarly, the City of Palm Springs has processed 
the Andreas Cove project proposal under a Negative Declaration, rather 
than the more rigorous Environmental Impact Report analysis. Moreover, 
the General Plans for most of the cities in the Coachella Valley 
inadequately address potentially significant development threats to the 
long-term conservation of Peninsular bighorn sheep. The Service is 
aware of approximately 15 additional project proposals that have the 
potential to adversely effect this species.
    Regional conservation planning efforts are underway within the 
range of the Peninsular bighorn sheep, but these efforts are either 
incomplete, awaiting funding and implementation, or unproven for this 
distinct population segment. Given the development pressures and 
history of project approval in the Coachella Valley, the Service is 
concerned for the remaining Peninsular bighorn sheep in this area.
    The Peninsular bighorn sheep receives some benefit from the 
presence of least Bell's vireo (Vireo bellii pusillus) and southwestern 
willow flycatcher (Empidonax traillii extimus) in its range; both are 
federally listed species. However, this benefit is limited due to the 
specialized habitats (riparian woodland) utilized by these birds. 
Similarly, section 404 of the Clean Water Act provides limited 
protection to small portions of the Peninsular bighorn sheep's range 
through the U.S. Army Corps of Engineers' (Corps) regulation of the 
discharge of dredged and fill material into certain waters and wetlands 
of the United States.
    The California Fish and Game Code provides for management and 
maintenance of bighorn sheep. The policy of the State is to encourage 
the preservation, restoration, utilization, and management of 
California's bighorn sheep. The CDFG supports the concept of separating 
livestock from bighorn sheep (to create buffers to decrease the 
potential for disease transmission) through purchase and elimination of

[[Page 13146]]

livestock allotments. However, it has not been a policy of the CDFG to 
revoke current State livestock permits (State of California 1988), nor 
does the State have authority to regulate grazing practices on Federal 
lands. Accordingly, State listing has not prompted the BLM or USFS to 
effectively address disease transmission associated with Federal 
livestock grazing programs.
    Since the Peninsular bighorn sheep was listed by the State of 
California in 1971, the CDFG has: (1) prepared management plans for the 
Santa Rosa Mountains and for the McCain Valley area of eastern San 
Diego County; (2) acquired 30,000 acres of land in the Santa Rosa 
Mountains; (3) initiated demographic, distributional, and disease 
research; and (4) established three ecological reserves that protect 
important watering sites. These actions are important to Peninsular 
bighorn sheep conservation, but, are not sufficient to stem the long-
term population decline.
    The BLM and the USFS manage lands that contain habitat for 
Peninsular bighorn sheep. The BLM has management plans that include 
management activities for the Peninsular bighorn sheep. The San 
Bernardino National Forest Plan also addresses the Peninsular bighorn 
sheep. Both agencies administer grazing allotments on portions of their 
land. The Bureau of Indian Affairs, Bureau of Reclamation, and the 
Department of Defense also conduct activities within or adjacent to the 
range of this distinct population segment. The BLM, CDFG, CDPR, USFS 
Service, and Service are jointly developing the Peninsular Ranges 
Coordinated Bighorn Sheep Metapopulation Management Plan (BLM et al. 
1993). The completion of this plan is pending. Current Federal 
management plans have not stopped the decline in numbers of Peninsular 
bighorn sheep on Federal lands.
    E. Other natural or manmade factors affecting its continued 
existence. Recurrent drought, disturbance at watering sites, urban and 
agricultural water withdrawals, and domestic livestock use decrease the 
amount of water available for Peninsular bighorn sheep. In particular, 
small ewe groups are affected. Peninsular bighorn sheep, similar to 
other bighorn sheep, exhibit a seasonal pattern of distribution based 
on forage and water availability. Water is available via tenajas 
(natural catchment basins adjacent to streams), springs, and guzzlers. 
During late summer and early winter (July to November), when water 
requirements and breeding activities are at a peak, the sheep tend to 
concentrate near water sources, particularly as tenajas and springs dry 
up. During this time, the sheep depend on reliable water and food 
sources. Bighorn sheep require a quantity of water approximately equal 
to 4 percent of their body weight (1 gallon) per day during the summer 
months and a dependable water supply is needed at about 2-mile 
intervals (Blong and Pollard 1968). When water is not available in 
sufficient quantities (especially during hot, dry weather) the 
mortality rate for older sheep, lambs, and sick or injured animals is 
likely to increase.
    Several studies have shown that bighorn sheep respond to human 
presence (as well as roads and housing developments) by altering 
behavior patterns to avoid contact. This behavioral response may 
preclude or disrupt sheep use of essential water sources, mineral 
licks, feeding areas, or breeding sites (Hicks and Elder 1979, Hamilton 
et al. 1982, MacArthur et al. 1982, Miller and Smith 1985, Krausman and 
Leopold 1986, Sanchez et al. 1988). Proposed country club/residential 
developments that have been approved or proposed within or immediately 
adjacent to Peninsular bighorn sheep habitat will substantially 
increase human activity. Unrestricted use of hiking and mountain bike 
trails in sensitive areas could further disrupt bighorn behavior and 
negatively affect this species. A reversal in behavior has been noted 
by the immediate return of Peninsular bighorn sheep to areas that were 
recently closed off to hikers in the Santa Rosa Mountains (e.g., 
Magnesia Falls Canyon) (Ken Corey, U.S. Fish and Wildlife Service, 
pers. com., 1997)
    Some species of ornamental plants, associated with urban 
developments, have been attributed to causes of mortality in bighorn 
sheep (Wilson et al. 1980, DeForge 1997). Between 1991 and 1996, five 
Peninsular bighorn sheep in the northern Santa Rosa Mountains ewe group 
died from ingesting ornamental, toxic plants such as oleander (Nerium 
oleander) and laurel cherry (Prunus sp.) (DeForge and Ostermann 1997). 
A toxic, ornamental nightshade plant may have caused the death of a 
young ram (a necropsy revealed an unknown species of nightshade) in 
Palm Springs in 1970 (Weaver and Mensch 1970). Due to the absence of 
comprehensive studies of the toxicity of ornamental plants to bighorn 
sheep, only the two plant species mentioned above are known to be 
poisonous to the Peninsular bighorn sheep. It is expected that more 
species of ornamental plants are toxic to this species (DeForge, pers. 
comm. 1997).
    Collisions with vehicles also are a source of Peninsular bighorn 
sheep mortality. Turner (1976) reported Peninsular bighorn sheep being 
killed as a result of automobile collisions on Highway 74 in areas 
where blind curves exist in known sheep movement areas. The Thunderbird 
Estates and golf course is located across Highway 111 (on the east 
side) from Peninsular bighorn sheep habitat in Rancho Mirage. 
Individuals from the northern Santa Rosa Mountains ewe group cross over 
Highway 111, or use a flood control channel that is under Highway 111, 
to access forage and water at this golf course (DeForge, pers. comm 
1997). Dominant ewes will lead five to seven other ewes and rams to the 
golf course across Highway 111 which has led to collisions with 
automobiles (DeForge, pers. comm. 1997). DeForge and Ostermann (1997) 
also reported that nine Peninsular bighorn sheep in the Santa Rosa 
Mountains were hit and killed by automobiles between 1991 and 1996, and 
in combination with other urban-related factors, accounted for the 
majority of mortalities.
    The Peninsular bighorn sheep apparently is currently functioning as 
a metapopulation (BLM et al. 1993, Boyce et al. 1997); there is 
interaction between separate groups. However, the potential loss of 
dispersal corridors and habitat fragmentation by residential and 
commercial development and roads and highways may isolate certain 
groups. Isolation increases the chances for inbreeding depression by 
preventing rams from moving among ewe groups and eliminating 
exploratory and colonizing movements by ewe groups into new or former 
habitat. Inbreeding and the resultant loss of genetic variability can 
result in reduced adaptiveness, viability, and fecundity, and may 
result in local extirpations. Small, isolated groups are also subject 
to extirpation by naturally occurring events such as fire. Although 
inbreeding has not been demonstrated in the Peninsular bighorn sheep, 
the number of sheep occupying many areas is critically low. The minimum 
size at which an isolated group can be expected to maintain itself 
without the deleterious effects of inbreeding is not known. Researchers 
have suggested that a minimum effective population size of 50 is 
necessary to avoid short-term inbreeding depression, and 500 to 
maintain genetic variability for long-term adaptation (Franklin 1980). 
Berger (1990) studied bighorn sheep populations in the southwestern 
United States and found that all populations with less than 50 
individuals became extinct within 50 years. Berger (1990) concluded 
that extinction in

[[Page 13147]]

populations of this size cannot be overcome without intensive 
management, because 50 individuals, even in the short-term, do not 
constitute a viable population size. This issue is complicated because 
of the structure and function of bighorn sheep populations. Because 
they appear to be functioning as a type of metapopulation, the 
effective size of a population is actually larger. That is, adjacent 
groups must be taken into consideration in determining the long-term 
viability of a group or an assemblage of groups. For example, connected 
groups (ewe herds) can be isolated from the other groups through the 
loss of intervening groups. The loss of an intervening group is 
detrimental to the long-term viability of the overall population due to 
the loss itself, and through the potential genetic and demographic 
isolation of the remaining groups. Other causes of mortality such as 
road kills may significantly affect the continued survival of small 
groups that are experiencing depressed recruitment.
    The Service has carefully assessed the best scientific and 
commercial information available regarding the past, present, and 
future threats faced by this distinct vertebrate population segment in 
determining to make this rule final. Based on this evaluation, the 
Service finds that the Peninsular bighorn sheep is in danger of 
extinction throughout a significant portion of its range due to: (1) 
disease; (2) insufficient lamb recruitment; (3) habitat loss, 
degradation, and fragmentation by urban and commercial development; and 
(4) predation coinciding with low population numbers. Because of the 
threats and the decline of the species, the preferred action is to list 
the Peninsular bighorn sheep as endangered. Threatened status would not 
accurately reflect the rapid, ongoing decline of, and imminent threats 
to, the Peninsular bighorn sheep.

Status of Peninsular Bighorn Sheep Currently Held in Captivity

    Under section 9(b)(1) of the Act, certain prohibitions applicable 
to listed species would not apply to Peninsular bighorn sheep held in 
captivity or in a controlled environment on the date of publication of 
any final rule, provided that such holding and subsequent holding or 
use of these sheep was not in the course of a commercial activity. In 
addition, certain prohibitions applicable to listed species would not 
apply to Peninsular bighorn sheep taken by hunters prior to publication 
of this final rule.

Critical Habitat

    Critical habitat is defined in section 3 of the Act as: (i) the 
specific areas within the geographical area occupied by a species, at 
the time it is listed in accordance with the Act, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographical area occupied by a species at the time it was listed, upon 
a determination that such areas are essential for the conservation of 
the species. ``Conservation'' means the use of all methods and 
procedures needed to bring the species to the point at which listing 
under the act is no longer required.
    Section 4(a)(3) of the Act, as amended, and its implementing 
regulations (50 CFR 424.12) require that, to the maximum extent prudent 
and determinable, the Secretary designate critical habitat at the time 
a species is determined to be endangered or threatened. The Service 
finds that designation of critical habitat is not prudent for the 
Peninsular bighorn sheep distinct population segment. Service 
regulations (50 CFR 424.12(a)(1)) state that designation of critical 
habitat is not prudent when one or both of the following situations 
exist: (1) the identification of critical habitat can be expected to 
increase the degree of threat to the species, or (2) such designation 
of critical habitat would not be beneficial to the species.
    The Service concludes that critical habitat designation for the 
Peninsular bighorn sheep is not prudent because both of the described 
situations exist. Bighorn sheep life history research and population 
status surveys have been conducted for over 40 years (DeForge et al. 
1995) and much of this work is ongoing. As a consequence, the 
distribution and location of Peninsular bighorn sheep in the United 
States are well known within the scientific community. The Peninsular 
bighorn sheep is a majestic and popular animal in the eyes of the 
general public. Attractive areas for recreational hiking and possible 
observation points for Peninsular bighorn sheep have been identified in 
commercially available information sources (Palm Springs Desert Access 
Guide (BLM 1978); Santa Rosa Mountains National Scenic Area Trails Map 
(Coachella Valley Trails Council 1995); Palm Canyon Trail Map 1995). 
The cumulative pressure of human attraction to the scenic canyons and 
mountains occupied by bighorn sheep has led to the proliferation of 
new, unauthorized trails that are becoming an increasing concern of 
land management agencies and scientific organizations. Annual aerial 
censuses by the Bighorn Institute and CDFG recently identified several 
new trails through important habitat areas in the vicinity of La Quinta 
(J. DeForge, pers. comm., 1998). Similarly, BLM recently discovered a 
newly constructed trail on its lands in the hills above Cathedral City 
and Rancho Mirage, through a lambing area. BLM and others are 
attempting to rehabilitate the trail (J. Dugan, pers. comm. 1997).
    The majority of sheep range is owned by State and Federal agencies 
and managed for multiple human uses, especially recreational pursuits. 
Four of eight ewe groups in the U.S. largely occur in the Anza Borrego 
State Park, renowned as a premier hiking and camping destination. The 
remaining four ewe groups largely occur within BLM's Santa Rosa 
Mountains National Scenic Area, which is intended to expand 
recreational opportunities through acquiring private lands for public 
use and enjoyment. Coachella Valley commercial interests are 
aggressively promoting and developing outdoor recreational industries 
that capitalize on the scenic beauty of the Santa Rosa and San Jacinto 
mountains. These industries and activities include jeep nature tours, 
mountain biking, hiking, horseback riding, dog walking, camping, sight-
seeing, and other ecotourist forms of recreation in bighorn sheep 
habitat that often use bighorn sheep images as advertising themes, 
corporate and civic logos, etc. During the more temperate months of 
October through April, the Coachella Valley attracts millions of 
tourists and seasonal residents from across the Country and around the 
world. The timing of maximum human use levels corresponds with 
particularly sensitive periods in bighorn sheep life history, including 
the lambing season, rut, and the late summer water stress period.
    Publication of detailed critical habitat maps and descriptions, as 
required with critical habitat designation, would make the location of 
bighorn sheep more readily available to the general public and serve as 
further advertisement for human uses in sensitive areas. Human activity 
in bighorn sheep habitat has been identified as a threat (see Factor E 
of ``Summary of Factors Affecting the Species''). An increase in human 
activity, even when harm is not intended, would disrupt bighorn sheep 
behavior and could cause abandonment of essential environments (e.g., 
lambing areas or watering holes) (Cowan and Geist 1971, Hicks and Elder 
1979,

[[Page 13148]]

MacArthur et al. 1982, Hamilton et al. 1982, Sanchez et al. 1988). 
Desert-dwelling bighorn sheep are inherently slow to recolonize vacant 
habitat (Bleich et al. 1990). Thus, critical habitat designation would 
increase the degree of threat to the Peninsular bighorn sheep and 
result in harm to this distinct population segment rather than aid in 
its conservation.
    In addition, designation of critical habitat likely would not 
benefit the conservation of this distinct population segment. Section 
7(a)(2) of the Act requires Federal agencies, in consultation with the 
Service, to ensure that any action authorized, funded or carried out by 
such agency, does not jeopardize the continued existence of a federally 
listed species or result in the destruction or adverse modification of 
designated critical habitat. This latter requirement is the only 
mandatory legal consequence of a critical habitat designation. Critical 
habitat designation provides protection only on Federal lands or on 
private or State lands when there is Federal involvement through 
authorization or funding of, or participation in, a project or 
activity. Almost half the habitat land area occupied by the Peninsular 
bighorn sheep in the United States is owned and managed by the State of 
California. The remainder is almost evenly divided between private and 
Federal ownership (see BACKGROUND section). The protection afforded 
under section 7 seldom extends onto State lands. Therefore, any 
potential designation of critical habitat on State lands (which account 
for about half of the U.S. range) would not be expected to benefit the 
bighorn sheep. Similarly, a section 7 nexus would seldom occur on 
private lands occupied by bighorn sheep because arid, upland habitats 
typically do not support jurisdictional waters or wetlands regulated 
under section 404 of the Clean Water Act.
    Section 7 consultation is most likely to occur with the BLM 
concerning minerals rights for mining, granting of rights-of-way, 
recreational use permits, and management of grazing allotments. In 
addition, consultation with the Corps through permit application review 
under section 404 of the Clean Water Act may occur.
    With about 75 percent of the U.S. range occurring on State and 
private lands with a limited section 7 nexus, potential benefits 
largely would be restricted to the remaining 25 percent of habitat that 
occurs on Federal lands. However, designation of those areas necessary 
for conservation (i.e., recovery) of the species cannot be accomplished 
primarily on Federal lands. In addition, for recovery planning under 
section 4 of the Act, designating critical habitat would not aid in 
creating a Peninsular bighorn sheep management plan, addressing 
transmission of diseases and establishing numerical population goals 
for long-term survival of the species, nor directly affect areas not 
designated as critical habitat. These types of issues will be addressed 
through the recovery planning process, wherein the Service establishes 
a framework for cooperation among key stakeholders and interest groups 
to prepare and implement a recovery plan based on private and public 
sector collaboration in defining and achieving recovery.
    The Service acknowledges that critical habitat designation may 
provide some benefits to a species by identifying areas important to a 
species' conservation and calling attention to those areas in special 
need of protection. A critical habitat designation contributes to 
species conservation primarily by highlighting important habitat areas 
and by describing the features within those areas that are essential to 
the species. However, the Service is pursing alternative means to 
achieve the objective of disseminating information on important habitat 
areas by working directly with Federal and State land agencies and 
private landowners to develop a coordinated management plan for the 
Peninsular bighorn sheep.
    In summary, there would be substantial risks to this bighorn sheep 
distinct population segment by publicizing maps of areas of occupancy 
and locations of habitats. Weighed against the fact that there would be 
little or no additional benefit to the species, the Service finds that 
designation of critical habitat for the Peninsular bighorn sheep is not 
prudent.
    The Service will continue in its efforts to obtain more information 
on Peninsular bighorn sheep biology and ecology, including essential 
habitat characteristics, current and historic distribution, disease 
control, and other factors that would contribute to the conservation of 
the species. The information resulting from these efforts will be used 
to identify measures needed to achieve conservation of the species, as 
defined under the Act. Such measures could include, but are not limited 
to, development of a recovery plan, agency management plans, and 
conservation agreements with the State, other Federal agencies, local 
governments, and private landowners and organizations.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition, recovery actions, 
requirements for Federal protection, and prohibitions against certain 
activities. Recognition through listing encourages and results in 
conservation actions by Federal, State, and private agencies, groups 
and individuals. The Act provides for possible land acquisition and 
cooperation with the States and requires that recovery actions be 
carried out for all listed species. The protection required of Federal 
agencies and the prohibitions against taking and harm are discussed, in 
part, below.
    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened and with respect to its critical 
habitat, if any is being designated. Regulations implementing this 
interagency cooperation provision of the Endangered Species Act are 
codified at 50 CFR part 402. Section 7(a)(4) of the Act requires 
Federal agencies to confer informally with the Service on any action 
that is likely to jeopardize the continued existence of a proposed 
species or result in destruction or adverse modification of proposed 
critical habitat. If a species is subsequently listed, section 7(a)(2) 
requires Federal agencies to ensure that activities they authorize, 
fund, or carry out are not likely to jeopardize the continued existence 
of such a species or to destroy or adversely modify its critical 
habitat. If a Federal agency action may affect a listed species or its 
critical habitat, the responsible Federal agency must enter into 
consultation with the Service.
    Federal agency actions that may require conference and/or 
consultation as described in the preceding paragraph include those 
within the jurisdiction of the Bureau of Indian Affairs, BLM, USFS, 
Corps, and Department of Defense. The Peninsular bighorn sheep occurs 
on private and State-owned land as well. Where the Peninsular bighorn 
sheep occurs on private lands there is little or no Federal involvement 
except where access is provided over Federal lands or permits are 
required from the Corps under the Clean Water Act. The BLM and COE are 
currently conferencing with the Service under section 7 of the Act to 
address the impacts associated with granting rights-of-way for several 
activities (e.g., recreational access).
    The Act and implementing regulations found at 50 CFR 17.21 set

[[Page 13149]]

forth a series of general prohibitions and exceptions that apply to all 
endangered wildlife. The prohibitions, as codified at 50 CFR 17.21, in 
part, make it illegal for any person subject to the jurisdiction of the 
United States to take (including harass, harm, pursue, hunt, shoot, 
wound, kill, trap, capture, collect, or attempt any such conduct), 
import or export, transport in interstate or foreign commerce in the 
course of commercial activity, or sell or offer for sale in interstate 
or foreign commerce any listed species. It is also illegal to possess, 
sell, deliver, carry, transport, or ship any such wildlife that has 
been taken illegally. Certain exceptions apply to agents of the Service 
and State conservation agencies.
    Permits may be issued to carry out otherwise prohibited activities 
involving endangered wildlife species under certain circumstances. 
Regulations governing permits are at 50 CFR 17.22, 17.23, and 17.32. 
For endangered species, such permits are available for scientific 
purposes, to enhance the propagation or survival of the species, or for 
incidental take in connection with otherwise lawful activities.
    It is the policy of the Service, published in the Federal Register 
on July 1, 1994 (59 FR 34272), to identify to the maximum extent 
practical at the time a species is listed those activities that would 
or would not constitute a violation of section 9 of the Act. The intent 
of this policy is to increase public awareness of the effect of a 
listing on proposed and ongoing activities within a species' range. 
Activities that the Service believes could potentially harm the 
Peninsular bighorn sheep and result in take include, but are not 
limited to:
    (1) Unauthorized trapping, capturing, handling or collecting of 
Peninsular bighorn sheep. Research activities, where sheep are trapped 
or captured, will require a permit under section 10(a)(1)(A) of the 
Endangered Species Act.
    (2) Unauthorized destruction or degradation of habitat through, but 
not limited to, clearing vegetation, bulldozing terrain, and disturbing 
natural drainage systems;
    (3) Unauthorized destruction of habitat that will likely lead to 
habitat fragmentation and isolation of ewe herds.
    (4) Unauthorized livestock grazing that could result in 
transmission of disease or habitat destruction.
    Activities that the Service believes are unlikely to result in a 
violation of section 9 are:
    (1) Possession, delivery, or movement, including interstate 
transport and import into or export from the United States, involving 
no commercial activity, of dead specimens of this distinct population 
segment that were collected prior to the date of publication in the 
Federal Register of the final regulation adding this distinct 
population segment to the list of endangered species;
    (2) Accidental roadkills or injuries by vehicles conducted in 
compliance with applicable laws, on designated public roads as 
constructed upon the date of publication in the Federal Register of the 
final regulation adding this distinct population segment to the list of 
endangered species;
    (3) Normal, authorized recreational activities in designated 
campsites and on authorized trails.
    (4) Lawful residential lawn maintenance activities including the 
clearing of vegetation as a fire break around one's personal residence.
    Questions regarding any specific activities should be directed to 
the Service's Carlsbad Field Office (see ADDRESSES section). Requests 
for copies of the regulations regarding listed wildlife and about 
prohibitions and permits may be addressed to the U.S. Fish and Wildlife 
Service, Ecological Services, Endangered Species Permits, 911 Northeast 
11th Avenue, Portland, Oregon 97232-4181 (503/231-6241; FAX 503/231-
6243)

Reasons for Effective Date

    The Service is concerned that the issuance of the final rule for 
the Peninsular bighorn sheep may result in the destruction of habitat 
essential for maintaining the San Jacinto and Santa Rosa Mountain 
herds. In addition, any delay in the effective date of this rule 
provides an opportunity for habitat destruction in other portions of 
its range in the United States. Habitat has been destroyed outside the 
regulatory process at the Traditions Project in La Quinta. There is an 
existing golf course development proposal to grade essential habitat in 
the Palm Springs area. Because of the immediate threat posed by these 
activities, the Service finds that good cause exists for this rule to 
take effect immediately upon publication in accordance with 5 U.S.C. 
Sec. 553(d)(3).

National Environmental Policy Act

    The Fish and Wildlife Service has determined that an Environmental 
Assessment, as defined under the authority of the National 
Environmental Policy Act of 1969, need not be prepared in connection 
with regulations adopted pursuant to section 4(a) of the Endangered 
Species Act of 1973, as amended. A notice outlining the Service's 
reasons for this determination was published in the Federal Register on 
October 25, 1983 (48 FR 49244).

Required Determinations

    This rule does not contain collections of information that require 
approval by the Office of Management and Budget under 44 U.S.C. 3501 et 
seq.

References Cited

    A complete list of references cited in this rule is available upon 
request from the Carlsbad Field Office of the U.S. Fish and Wildlife 
Service (see ADDRESSES section).
    Author: The primary author of this final rule is Arthur Davenport 
of the Carlsbad Field Office (see ADDRESSES section).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
record-keeping requirements, Transportation.

Regulation Promulgation

    Accordingly, the Service amends Part 17, Subchapter B of the 
Chapter I, Title 50 of the Code of Federal Regulations, as set forth 
below:

PART 17--[AMENDED]

    1. The authority citation for part 17 continues to read as follows:

    Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat 3500; unless otherwise noted.

    2. Amend Sec. 17.11(h) by adding the following, in alphabetical 
order under MAMMALS, to the List of Endangered and Threatened Wildlife:


Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

[[Page 13150]]


--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Species                                                    Vertebrate                                                           
--------------------------------------------------------                        population where                                  Critical     Special  
                                                            Historic range       endangered or         Status      When listed    habitat       rules   
           Common name                Scientific name                              threatened                                                           
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mammals:                                                                                                                                                
                                                                                                                                                        
                   *                  *                  *                  *                  *                  *                  *                  
Bighorn sheep, (Peninsular Ranges  Ovis canadensis.....  U.S.A. (western      U.S.A., Peninsular   E                       634           NA           NA
 population).                                             conterminous         Ranges of CA.                                                            
                                                          states), Canada                                                                               
                                                          (southwest),                                                                                  
                                                          Mexico (north).                                                                               
                                                                                                                                                        
                   *                  *                  *                  *                  *                  *                  *                  
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Dated: March 6, 1998.
Jamie Rappaport Clark,
Director, Fish and Wildlife Service.
[FR Doc. 98-6998 Filed 3-17-98; 8:45 am]
BILLING CODE 4310-55-P