[Federal Register: January 3, 2000 (Volume 65, Number 1)]
[Rules and Regulations]               
[Page 20-30]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]



Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AF59

Endangered and Threatened Wildlife and Plants; Final Rule To List 
the Sierra Nevada Distinct Population Segment of the California Bighorn 
Sheep as Endangered

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.


SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine 
endangered status pursuant to the Endangered Species Act of 1973, as 
amended (Act) for the Sierra Nevada distinct population segment of 
California bighorn sheep (Ovis canadensis californiana). This species 
occupies the Sierra Nevada of California, where it is known from five 
disjunct subpopulations along the eastern escarpment of the Sierra 
Nevada, and thought to total no more than 125 animals. All five 
subpopulations are estimated to be very small and are threatened by 
mountain lion (Felis concolor) predation, disease, naturally occurring 
environmental events, and genetic problems associated with small 
population size. We emergency listed this population segment of 
California bighorn sheep on April 20, 1999. The emergency listing was 
effective for 240 days. Immediately upon publication, this action 
continues the protection provided by the temporary emergency listing.

DATES: This final rule is effective on January 3, 2000.

Wildlife Service, Ventura Fish and Wildlife Office, 2493 Portola Rd. 
Suite B, Ventura, California 93003, (telephone 805/644-1766; facsimile 



    The bighorn sheep (Ovis canadensis) is a large mammal (family 
Bovidae) originally described by Shaw in 1804 (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 
these early works, 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, recent genetic studies question the validity 
of some of these subspecies and suggest a need to re-evaluate overall 
bighorn sheep taxonomy. For example, Sierra Nevada bighorn sheep appear 
to be more closely related to desert bighorn sheep than the O. c. 
californiana found in British Columbia (Ramey 1991, 1993). Regardless, 
the Sierra Nevada bighorn sheep meets our criteria for consideration as 
a distinct vertebrate population segment (as discussed below) and is 
treated as such in this final rule.
    The historical range of the Sierra Nevada bighorn sheep (Ovis 
canadensis californiana) includes the eastern slope of the Sierra 
Nevada, and, for at least one subpopulation, a portion of the western 
slope, from Sonora Pass in Mono County south to Walker Pass in Kern 
County, a total distance of about 346 kilometers (km) (215 miles (mi)) 
(Jones 1950; Wehauser 1979, 1980). By the turn of the century, about 10 
out of 20 subpopulations survived. The number dropped to five 
subpopulations at mid-century, and down to two subpopulations in the 
1970s, near Mount Baxter and Mount Williamson in Inyo County (Wehauser 
1979). Currently, five subpopulations of Sierra Nevada bighorn sheep 
occur, respectively, at Lee Vining Canyon, Wheeler Crest, Mount Baxter, 
Mount Williamson, and Mount Langley in Mono and Inyo Counties, three of 
which have been reintroduced using sheep obtained from the Mount Baxter 
subpopulation from 1979 to 1986 (Wehausen et al. 1987).
    The Sierra Nevada bighorn sheep is similar in appearance to other 
desert associated bighorn sheep. The species' pelage shows a great deal 
of color variation, ranging from almost white to fairly dark brown, 
with a white rump. Males and females have permanent horns; the horns 
are massive and coiled

[[Page 21]]

in males, and are smaller and not coiled in females (Jones 1950; 
Buechner 1960). As the animals age, their horns become rough and 
scarred, and will vary in color from yellowish-brown to dark brown. In 
comparison to many other desert bighorn sheep, the horns of the Sierra 
Nevada bighorn sheep are generally more divergent as they coil out from 
the base (Wehausen 1983). Adult male sheep stand up to 1 meter (m) (3 
feet (ft)) tall at the shoulder; males weigh up to 99 kilograms (kg) 
(220 pounds (lbs)) and females 63 kg (140 lbs) (Buechner 1960).
    The current and historical habitat of the Sierra Nevada bighorn 
sheep is almost entirely on public land managed by the U.S. Forest 
Service (FS), Bureau of Land Management (BLM), and National Park 
Service (NPS). The Sierra Nevada mountain range is located along the 
eastern boundary of California. Peaks vary in elevation from 1825 to 
2425 m (6000 to 8000 ft) in the north, to over 4300 m (14,000 ft) in 
the south adjacent to Owens Valley, and then drop rapidly in elevation 
in the southern extreme end of the range (Wehausen 1980). Most 
precipitation, in the form of snow, occurs from October through April 
(Wehausen 1980).
    Sierra Nevada bighorn sheep inhabit the alpine and subalpine zones 
during the summer, using open slopes where the land is rough, rocky, 
sparsely vegetated and characterized by steep slopes and canyons 
(Wehausen 1980; Sierra Nevada Bighorn Sheep Interagency Advisory Group 
(Advisory Group) 1997). Most of these sheep live between 3,050 and 
4,270 m (10,000 and 14,000 ft) in elevation in summer (John Wehausen, 
University of California, White Mountain Research Station, pers. comm. 
1999). In winter, they occupy high, windswept ridges, or migrate to the 
lower elevation sagebrush-steppe habitat as low as 1,460 m (4,800 ft) 
to escape deep winter snows and find more nutritious forage. Bighorn 
sheep tend to exhibit a preference for south-facing slopes in the 
winter (Wehausen 1980). Lambing areas are on safe precipitous rocky 
slopes. They prefer open terrain where they are better able to see 
predators. For these reasons, forests and thick brush usually are 
avoided if possible (J. Wehausen, pers. comm. 1999).
    Bighorn sheep are primarily diurnal, and their daily activity shows 
some predictable patterns that consists of feeding and resting periods 
(Jones 1950). Bighorn sheep are primarily grazers; however, they may 
browse woody vegetation when it is growing and very nutritious. They 
are opportunistic feeders selecting the most nutritious diet from what 
is available. Plants consumed include varying mixtures of grasses, 
browse (shoots, twigs, and leaves of trees and shrubs), and herbaceous 
plants, depending on season and location (Wehausen 1980). In a study of 
the Mount Baxter and Mount Williamson subpopulations, Wehausen (1980) 
found that grass, mainly Stipa speciosa (perennial needlegrass), is the 
primary diet item in winter. As spring green-up progresses, the bighorn 
sheep shift from grass to a more varied browse diet, which includes 
Ephedra viridis (Mormon tea), Eriogonum fasciculatum (California 
buckwheat), and Purshia species (bitterbrush).
    Sierra Nevada bighorn sheep are gregarious, with group size and 
composition varying with gender and from season to season. Spatial 
segregation of males and females occurs outside the mating season, with 
males more than 2 years old living apart from females and younger males 
for most of the year (Jones 1950; Cowan and Geist 1971; Wehausen 1980). 
Ewes generally remain in the same band into which they were born (Cowan 
and Geist 1971). During the winter, Sierra Nevada bighorn sheep 
concentrate in those areas suitable for wintering, preferably Great 
Basin habitat (sagebrush-steppe) at the very base of the eastern 
escarpment. Subpopulation size can number more than 100 sheep, 
including rams (this was observed at a time when the population size 
was larger than it is currently) (J. Wehausen, pers. comm. 1999). 
Breeding takes place in the fall, generally in November (Cowan and 
Geist 1971). Single births are the norm for North American wild sheep, 
but twinning is known to occur (Wehausen 1980). Gestation is about 6 
months (Cowan and Geist 1971).
    Lambing occurs between late April to early July, with most lambs 
born in May or June (Wehausen 1980, 1996). Ewes with newborn lambs live 
solitarily for a short period before joining nursery groups that 
average about six sheep. Ewes and lambs frequently occupy steep terrain 
that provides a diversity of slopes and exposures for escape cover. 
Lambs are precocious, and within a day or so, climb almost as well as 
the ewes. Lambs are able to eat vegetation within 2 weeks of their 
birth and are weaned between 1 and 7 months of age. By their second 
spring, they are independent of their mothers. Female lambs stay with 
ewes indefinitely and may attain sexual maturity during the second year 
of life. Male lambs, depending upon physical condition, may also attain 
sexual maturity during the second year of life (Cowan and Geist 1971). 
Average lifespan is 9 to 11 years in both sexes, though some rams are 
known to have lived to 12 to 14 years old (Cowan and Geist 1971; 
Wehausen 1980).

Distinct Vertebrate Population Segment

    Recent analyses of bighorn sheep genetics and morphometrics (e.g., 
size and shape of body parts) suggest reevaluation of the taxonomy of 
Sierra Nevada bighorn sheep (Ovis canadensis californiana) is necessary 
(Ramey 1991, 1993, 1995; Wehausen and Ramey 1993; Wehausen and Ramey 
2000 (in review)). A recent analysis of the taxonomy of bighorn sheep 
using morphometrics and genetics failed to support the current taxonomy 
(Ramey 1993, 1995; Wehausen and Ramey 1993; Wehausen and Ramey 2000 (in 
review)). This and other research (Ramey 1993) supports taxonomic 
distinction of the Sierra Nevada bighorn sheep relative to other nearby 
    The biological evidence supports recognition of Sierra Nevada 
bighorn sheep as a distinct vertebrate population segment for purposes 
of listing, as defined in our 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 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 (DPS) of bighorn sheep in the 
Sierra Nevada is discrete in relation to the remainder of the species 
as a whole. This DPS is geographically isolated and separate from other 
California bighorn sheep populations. There is no mixing of Sierra 
Nevada bighorn sheep with other bighorn sheep subspecies. This is 
supported by an evaluation of the population's genetic variability and 
morphometric analysis of skull and horn variation (Ramey 1993, 1995; 
Wehausen and Ramey 1993, 1994; Wehausen and Ramey 2000 (in review)). 
Sierra Nevada bighorn sheep males have particularly wide skulls but 
small horns, compared to other subspecies of bighorn sheep (Wehausen 
and Ramey 2000 (in review)). Also, Sierra Nevada bighorn

[[Page 22]]

sheep have a unique mitochondrial DNA pattern, different from other 
bighorn sheep populations (Ramey 1993, 1995). Mitochondrial DNA are 
genes that are inherited maternally in animals, and so are useful as 
genetic markers when researching population genetic questions (Ramey 
1993). Researchers suggest that all other populations of Ovis 
canadensis californiana be reassigned to other subspecies, leaving O. 
c. californiana (i.e., the subspecies found within the DPS that is the 
subject of this rule) only in the central and southern Sierra Nevada 
(Ramey 1993, 1995; Wehausen and Ramey 1993, 1994; Wehausen and Ramey 
2000 (in review)).
    The Sierra Nevada bighorn sheep DPS is biologically and 
ecologically significant to the species in that it constitutes the only 
population of California bighorn sheep inhabiting the Sierra Nevada. 
This DPS extends from Sonora Pass to Walker Pass, spanning 
approximately 346 km (215 mi) of contiguous suitable habitat in the 
United States. It is likely that there was gene flow in the past 
between bighorn sheep populations in the Sierra Nevada Mountains (Ovis 
canadensis californiana) and the White-Inyo Mountains (O. c. nelsoni), 
which are separated by Owens Valley (Ramey 1993, 1995). Genetic 
research indicates, however, that there are differences between the 
bighorn sheep populations in the Sierra Nevada and those in the White-
Inyo Mountains (Ramey 1991, 1993, 1995). Any dispersal that occurred 
between the two mountain ranges was likely by males since female 
bighorn sheep have a much lower rate of dispersal, probably due to the 
females not wanting to expose themselves or their lambs to predation by 
crossing the open terrain of Owens Valley (Ramey 1995). Movement 
between the populations apparently no longer occurs due to artificial 
barriers such as canals, highways, and fences (Jones 1950; Ramey 1993, 
1995). Sierra Nevada bighorn sheep also have different morphological 
features, and they are genetically different from other bighorn 
populations (Ramey 1991, 1993, 1995; Wehausen and Ramey 1993, 1994; 
Wehausen and Ramey 2000 (in review)). The loss of Sierra Nevada bighorn 
sheep would result in the total extirpation of bighorn sheep from the 
Sierra Nevada in California. The loss of Sierra Nevada bighorn sheep in 
the Sierra Nevada mountain range would also create a significant gap in 
bighorn sheep population distribution. The Sierra Nevada bighorn sheep 
are the most northern population of bighorn in California, with the 
closest population to the north being at Hart Mountain in Oregon 
(Jinelle, O'Connor, Lassen National Forest, pers. comm. 1999), and the 
closest population to the south and east being the White-Inyo Mountain 
bighorn populations. The loss of the Sierra Nevada bighorn sheep would 
further isolate bighorn sheep populations in Oregon from those in 
southern California.

Status and Distribution

    Historically, Sierra Nevada bighorn sheep populations occurred 
along and east of the Sierra Nevada crest from Sonora Pass (Mono 
County) south to Walker Pass (Olancha Peak) (Kern County) (Jones 1950; 
Wehausen 1979). Sheep apparently occurred wherever appropriate rocky 
terrain and winter range existed. With some exceptions, most of the 
populations wintered on the east side of the Sierra Nevada and spent 
summers near the crest (Wehausen 1979).
    Subpopulations of Sierra Nevada bighorn sheep probably began 
declining with the influx of gold miners to the Sierra Nevada in the 
mid-1880s, and those losses have continued through the 1900s (Wehausen 
1988). By the 1970s, only two subpopulations of Sierra Nevada bighorn 
sheep, those near Mount Baxter and Mount Williamson in Inyo County, are 
known to have survived (Wehausen 1979). Specific causes for the 
declines are unknown. Market hunting may have been a contributing 
factor as evidenced by menus from historic mining towns such as Bodie, 
which included bighorn sheep (Advisory Group 1997). However, with the 
introduction of domestic sheep in the 1860s and 1870s, wild sheep are 
known to have died in large numbers in several areas from disease 
contracted from domestic livestock (Jones 1950; Buechner 1960). Large 
numbers of domestic sheep were grazed seasonally in the Owens Valley 
and Sierra Nevada prior to the turn of the century (Wehausen 1988), and 
disease is believed to be the factor most responsible for the 
disappearance of bighorn subpopulations in the Sierra Nevada. Jones 
(1950) suggested that scabies were responsible for a die-off in the 
1870s on the Great Western Divide. Experiments have confirmed that 
bacterial pneumonia (teurellaecies), carried normally by domestic 
sheep, can be fatal to bighorn sheep (Foreyt and Jessup 1982).
    In 1971, the Sierra Nevada bighorn sheep was listed as threatened 
under the 1970 California Endangered Species Act (California Department 
of Fish and Game 1974, as cited by Advisory Group 1997; California 
Department of Fish and Game 1999). This classification led to the 
development and implementation of a State recovery plan, which has two 
main goals: (1) create at least two additional populations numbering at 
least 100 sheep that could serve as reintroduction stock in the event 
of a catastrophic decline in the Mount Baxter subpopulation, and (2) 
re-establish the sheep throughout historic ranges in the Sierra Nevada 
where biologically and politically feasible (Advisory Group 1997). 
Intensive field studies began in 1975 which provided accurate census 
data for the two surviving subpopulations. In 1979, re-introductions of 
sheep into historical habitat (also known as the restoration program) 
began and was conducted by several Federal and State agencies from 1979 
to 1988 (Advisory Group 1997). By 1979, only 220 sheep were known to 
exist in the Mount Baxter subpopulation, and 30 in the Mount Williamson 
subpopulation (Wehausen 1979). Sheep were obtained from the Mount 
Baxter subpopulation and transplanted to three historic locations, 
which were Lee Vining Canyon, Wheeler Crest, and Mount Langley 
(Wehausen 1996; Advisory Group 1997). Consequently, Sierra Nevada 
bighorn sheep now occur in five subpopulations in Mono and Inyo 
Counties : Lee Vining Canyon, Wheeler Crest, Mount Baxter, Mount 
Williamson, and Mount Langley. The Sierra Nevada bighorn sheep 
population reached a high of about 310 in 1985-86, but subsequent 
population surveys have documented a declining trend (J. Wehausen, 
pers. comm. 1999). Currently, it is estimated that the total Sierra 
Nevada bighorn sheep population is 125 animals (J. Wehausen, pers. 
comm. 1999).
    The following table best represents the total Sierra Nevada bighorn 
sheep population over various time periods. These totals represent the 
numbers of sheep emerging from winter in each of these years, and best 
documents the status of the population by incorporating winter 
mortality, especially of lambs born the previous year. These totals are 
not absolute values; numbers have been rounded to the nearest five (J. 
Wehausen, pers. comm. 1999). The continuing decline of the Sierra 
Nevada bighorn sheep has been attributed to a combination of the direct 
and indirect effects of predation (Wehausen 1996).

[[Page 23]]

  Table 1.--Sierra Nevada Bighorn Sheep Population Numbers, by Year (J.
                       Wehausen, Pers. Comm. 1999)
                                                 Number of
                     Year                       populations  Total sheep
1978..........................................            2          250
1985..........................................            4          310
1995..........................................            5          100
1996..........................................            5          110
1997..........................................            5          130
1998..........................................            5          100
1999..........................................            5        *125
*Note that the difference in population size between 1998 and 1999 is
  based on (1) a small band of bighorn sheep were located in Sand
  Mountain (Mount Baxter subpopulation), and (2) approximately 15 lambs
  were born to the Wheeler Crest subpopulation in 1999.

Previous Federal Action

    In our September 18, 1985, Notice of Review, we designated the 
Sierra Nevada bighorn sheep as a category 2 candidate and solicited 
status information (50 FR 37958). Category 2 candidate species included 
taxa for which we 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. Category 1 candidates 
were those species for which we had sufficient information on file to 
support issuance of proposed listing rules. In our January 6, 1989 (54 
FR 554), and November 21, 1991 (56 FR 58804), Notices of Review, we 
retained the Sierra Nevada bighorn sheep in category 2. Beginning with 
our February 28, 1996, Notice of Review (61 FR 235), we discontinued 
the designation of multiple categories of candidates, and we now 
consider only species that meet the definition of former category 1 as 
candidates for listing. At that point, the Sierra Nevada bighorn sheep 
was not identified as a candidate.
    On February 12, 1999, we received a petition dated February 9, 
1999, from the Friends of the Inyo, National Parks and Conservation 
Association, Natural Resources Defense Council, Sierra Nevada Bighorn 
Sheep Foundation, and The Wilderness Society, to list the Sierra Nevada 
bighorn sheep as endangered throughout its range, with a special 
request for an emergency listing under the Act. The petition provided 
information on the species' classification and biology, past and 
present conservation efforts, historic and current distribution, 
population trends, and threats facing this species, including small 
population effects, disease, predation and habitat curtailment, fire, 
and inadequacy of existing regulations.
    On April 20, 1999, we published an emergency rule to list the 
Sierra Nevada distinct population segment of California bighorn sheep 
as endangered (64 FR 19300), as well as a proposed rule (64 FR 19333) 
to list the species as endangered on that same date.
    The processing of this final rule conforms with our listing 
priority guidance published in the Federal Register on October 22, 1999 
(64 FR 57114). Highest priority is processing emergency listing rules 
for any species determined to face a significant and imminent risk to 
its well being (Priority 1). Second priority (Priority 2) is processing 
final determinations on proposed additions to the Federal lists of 
endangered and threatened wildlife and plants. Third priority is 
processing new proposals to add species to the lists. The processing of 
administrative petition findings (petitions filed under section 4 of 
the Act) is fourth priority. The processing of critical habitat 
determinations (prudency and determinability decisions) and proposed 
and final designations of critical habitat will no longer be subject to 
prioritization under the listing priority guidance. This final rule is 
a Priority 2 action and is being completed in accordance with the 
current listing priority guidance. We have updated this rule to reflect 
any changes in information concerning distribution, status, and threats 
since publication of the proposed rule.

Summary of Comments and Recommendations

    In the April 20, 1999, proposed rule (64 FR 19333), we requested 
all interested parties to submit factual reports or information that 
might contribute to development of a final rule. A 60-day comment 
period closed on June 21, 1999. We contacted appropriate Federal 
agencies, State agencies, county and city governments, scientific 
organizations, and other interested parties and requested comments. We 
published public notices of the proposed rule in the Inyo Register in 
Inyo County and Fresno Bee in Fresno County on May 8, 1999, and in the 
Mammoth Times in Mono County on May 13, 1999, which invited general 
public comment. We did not receive any requests for a public hearing. 
We re-opened the comment period on September 30, 1999, at the request 
of the Foundation for North American Wild Sheep and to solicit a peer 
review of the proposed rule. The comment period ended on October 15, 
    During the public comment period, we received written comments from 
39 individuals or organizations, with one commenter submitting comments 
during both comment periods. All but two commenters supported the 
listing of the Sierra Nevada bighorn sheep. One commenter sent a letter 
refuting some information presented to us by another commenter. Issues, 
and our response to each, are summarized below.
    Issue 1: One commenter requested that we recognize a long-term 
ecosystem approach for recovery that includes healthy predator/prey 
    Our Response: We agree that recovery should be based on restoring, 
to the greatest extent possible, the ecosystem such that the natural 
dynamics of predator/prey relationships function with minimal or no 
human intervention. We recognize this in the rule, and the actual goals 
and tasks necessary to achieve recovery of the species will be 
discussed in detail in the Sierra Nevada bighorn sheep recovery plan.
    Issue 2: Two commenters asked that we designate critical habitat 
for the Sierra Nevada bighorn sheep.
    Our Response: In the emergency rule, we indicated that designation 
of critical habitat was not determinable for the Sierra Nevada bighorn 
sheep due to a lack of information sufficient to perform the required 
analysis of impacts of the designation. As discussed below in the 
critical habitat section, we have re-examined the question of whether 
critical habitat is not determinable and have determined that there is 
sufficient information to do the required analysis and that designation 
of critical habitat for the species is prudent.
    As explained in detail in the Final Listing Priority Guidance for 
FY 2000 (64 FR 57114), our listing budget is currently insufficient to 
allow us to immediately complete all of the listing actions required by 
the Act. We will defer critical habitat designation for the Sierra 
Nevada bighorn sheep in order to allow us to concentrate our limited 
resources on higher priority critical habitat (including court-ordered 
designations) and other listing actions, while allowing us to put in 
place protections needed for the conservation of the Sierra Nevada 
bighorn sheep without further delay.
    We plan to employ a priority system for deciding which outstanding 
critical habitat designations should be addressed first. We will focus 
our efforts on those designations that will provide the most 
conservation benefit, taking into consideration the efficacy of 
critical habitat designation in addressing the threats to the species, 
and the magnitude and immediacy of those

[[Page 24]]

threats. We will develop a proposal to designate critical habitat for 
the Sierra Nevada bighorn sheep as soon as feasible, considering our 
workload priorities.
    Issue 3: Several commenters stated that we should require other 
Federal agencies to utilize their authorities to eliminate grazing 
permits on Federal land, and initiate formal consultation under section 
7 of the Act.
    Our Response: Upon emergency listing of the Sierra Nevada bighorn 
sheep, we notified all Federal agencies of this listing and their 
responsibilities under section 7 of the Act to consult with us on 
actions that may affect the Sierra Nevada bighorn sheep. During the 
emergency listing period, the FS consulted on their actions for 
permitting domestic sheep grazing, conducting prescribed burns to 
enhance bighorn sheep winter habitat, as well as removing wreckage from 
a crashed airplane in bighorn sheep habitat. With the final listing of 
this species, we will continue to expect Federal agencies to comply 
with section 7 of the Act and consult with us, and we will work with 
these Federal agencies, as well as State agencies, to reduce threats to 
the species.
    Issue 4: One commenter requested that we clarify our policies and 
procedures on deterrence and removal of Sierra Nevada bighorn sheep 
predators, and that the final rule should include clear guidelines for 
how we will manage predators.
    Our Response: In accordance with our Interagency Cooperative Policy 
on Recovery Plan Participation and Implementation Under the Endangered 
Species Act (July 1, 1994; 59 FR 34272), and our recovery guidelines, 
we will develop a recovery plan that is ecosystem-based, and clearly 
identify quantifiable recovery criteria and goals, and we will clearly 
identify those management actions necessary to achieve recovery of the 
    Issue 5: One commenter stated that we should conduct studies to 
examine biological effects of differential removal of mountain lions on 
the Sierra Nevada bighorn sheep.
    Our Response: We agree that this should be an important goal of 
recovery efforts. In addition to specific management actions, specific 
research aimed at better understanding the species and ecosystem (e.g., 
predator/prey relationships, population demography) will be identified 
in the recovery plan.
    Issue 6: One commenter stated that Federal listing is no longer 
warranted because: 1) Assembly Bill (A. B.) 560 was recently signed 
into State law providing the California Department of Fish and Game 
(CDFG) to remove or take mountain lions that are perceived to be a 
threat to the sheep; (2) CDFG was appropriated State funds for the 
recovery of the Sierra Nevada bighorn sheep; and (3) Federal agencies 
and the Los Angeles Department of Water and Power have demonstrated 
good faith efforts at reducing the likelihood of contact between 
domestic sheep and the Sierra Nevada bighorn sheep.
    Our Response: We disagree. In evaluating the need for listing, we 
must look at a variety of factors affecting the species. This DPS of 
California bighorn sheep meets the definition of an endangered species 
based on several factors, only one of which is mountain lion predation. 
We agree that the passage and signing into law of A. B. 560 provides an 
additional ability to protect the Sierra Nevada bighorn sheep from 
mountain lions, as well as funds for recovery efforts. However, while 
this law will reduce the threat from mountain lion predation, it will 
not completely eliminate it. In addition, this legislation was enacted 
very recently, in September of 1999, and little time has passed to 
allow an evaluation of its effectiveness. We also agree that the CDFG 
was appropriated funds for the recovery of the species, however, these 
funds do not mean that all of the threats to the species have been 
removed such that listing is unnecessary. We also agree that the 
Federal agencies and Los Angeles Department of Water and Power have 
demonstrated good faith efforts at reducing the likelihood of contact 
between domestic and wild sheep. However, these efforts have come about 
due to the emergency listing and the subsequent requirement that 
Federal agencies must consult with us to ensure that their actions do 
not jeopardize the continued existence of the species.

Peer Review

    In accordance with our July 1, 1994, Interagency Cooperative Policy 
for Peer Review in Endangered Species Act Activities (59 FR 34270), we 
solicited the expert opinions of three independent specialists 
regarding pertinent scientific or commercial data and assumptions 
relating to bighorn sheep ecology, predator/prey relationships, and 
disease considered in the proposed rule (64 FR 19333). The purpose of 
such a review is to ensure that listing decisions are based on 
scientifically sound data, assumptions, and analyses, including input 
from appropriate experts. All three reviewers sent us a letter during 
the public comment period supporting the listing of the Sierra Nevada 
bighorn sheep. One of the three provided additional documentation on 
disease threats to bighorn sheep from domestic sheep; another provided 
conservation and recovery recommendations. Information and suggestions 
provided by the reviewers were considered in developing this final 
rule, and incorporated where applicable.

Summary of Factors Affecting the Species

    After a thorough review and consideration of all information 
available, we have determined that the Sierra Nevada bighorn sheep DPS 
warrants classification as an endangered species. We followed 
procedures found at section 4 of the Act and regulations (50 CFR part 
424) issued to implement the listing provisions of the Act. We 
determine a species 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 Sierra Nevada bighorn sheep DPS (Ovis 
canadensis californiana), are as follows:

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    Habitat throughout the historic range of Sierra Nevada bighorn 
sheep remains essentially intact; the habitat is neither fragmented nor 
degraded. However, by 1900, about half of the Sierra Nevada bighorn 
sheep populations were lost, most likely because of the introduction of 
diseases by domestic livestock, and illegal hunting (Advisory Group 
1997). Beginning in 1979, animals from the Mount Baxter subpopulation 
were translocated to reestablish subpopulations in Lee Vining Canyon, 
Wheeler Crest, and Mount Langley in Mono and Inyo Counties in order to 
re-establish the species in historical habitat (Advisory Group 1997). 
Currently, Sierra Nevada bighorn sheep are limited to five 
subpopulations. Almost all of the historical and current habitat is 
administered by either the FS, BLM, or NPS, though there are some small 
parcels of inholdings within the species' range which are owned by the 
Los Angeles Department of Water and Power. Also, there are some 
patented mining claims in bighorn sheep habitat, but the total acreage 
is small.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    During the period of the California gold rush (starting about 
1849), hunting to supply food for mining towns may have played a role 
in the decline of the population (Wehausen 1988). Besides

[[Page 25]]

being sought as food, Sierra Nevada bighorn sheep were also killed by 
sheepmen who considered the species competition for forage with 
domestic sheep. The decimation of several wildlife species in the late 
1800s prompted California to pass legislation providing protection to 
several species including bighorn sheep (Jones 1950; Wehausen 1979).
    Commercial and recreational hunting of Sierra Nevada bighorn sheep 
is not permitted under State law. There is no evidence that other 
commercial, recreational, scientific, or educational activities are 
currently a threat. Poaching does not appear to be a problem at this 

C. Disease or Predation

    Disease is believed to have been the major contributing factor 
responsible for the precipitous decline of Sierra Nevada bighorn sheep 
starting in the late 1800s (Foreyt and Jessup 1982).
    Bighorn sheep are host to a number of internal and external 
parasites, including ticks, lice, mites, tapeworms, roundworms, and 
lungworms. Most of the time, parasites are present in relatively low 
numbers and have little effect on individual sheep and populations 
(Cowan and Geist 1971).
    Cattle were first introduced into the Sierra Nevada in 1860s but 
were replaced with domestic sheep that could graze more extensively 
over the rugged terrain (Wehausen et al. 1987; Wehausen 1988). Large 
numbers of domestic sheep were grazed seasonally in the Sierra Nevada 
prior to the turn of the century, and the domestic sheep would use the 
same ranges as the wild sheep, occasionally coming into direct contact 
with them. Both domestic sheep and cattle can act as disease 
reservoirs. Scabies, most likely contracted from domestic sheep, caused 
a major decline of bighorn sheep in California in the 1870s to the 
1890s, and caused catastrophic die-offs in other parts of their range 
(Buechner 1960). A die-off of bighorn sheep in the 1870s on the Great 
Western Divide (Mineral King area of Sequoia National Park) was 
attributed to scabies, presumably contracted from domestic sheep (Jones 
    Die-offs from pneumonia contracted from domestic sheep is another 
important cause of losses. In 1988, a strain of pneumonia, apparently 
contracted from domestic sheep, wiped out the reintroduced South Warner 
Mountains herd of bighorn sheep (David A. Jessup, CDFG, in litt. 1999). 
These bighorn sheep, which included Sierra Nevada bighorn sheep, died 
of fibrinopurulent bronchopneumonia, caused by a virulent strain of 
Pasteurella species bacteria. Domestic sheep had been observed running 
with the bighorn prior to this outbreak (D. Jessup, in litt. 1999). 
Native bighorn sheep cannot tolerate strains of respiratory bacteria 
such as Pasteurella species, carried normally by domestic sheep, and 
close contact with domestic animals results in transmission of disease 
and subsequent deaths of the exposed animals (Foreyt and Jessup 1982). 
Similar die-offs of bighorn sheep populations have occurred elsewhere, 
such as in Lava Beds National Monument, California, and in Gerlach, 
Nevada, where it was documented that domestic sheep came into contact 
with wild sheep (Foreyt and Jessup 1982; D.A. Jessup, in litt. 1999).
    Bighorn sheep can also develop pneumonia independent of contact 
with domestic sheep. Lungworms of the genus Protostrongylus are often 
an important contributor to the pneumonia disease process in some 
situations (J. Wehausen, pers. comm. 1999). Lungworms are carried by an 
intermediate host snail, which is ingested by a sheep as it is grazing. 
Lungworm often exists in a population without causing a problem. 
However, if the sheep are stressed in some way, they may develop 
bacterial pneumonia, which is complicated by lungworm infestation. 
Bacterial pneumonia is usually a sign of weakness caused by some other 
agent such as a virus, parasite, poor nutrition, predation, human 
disturbance, or environmental or behavioral stress that lowers the 
animal's resistence to disease (Wehausen 1979; Foreyt and Jessup 1982). 
Bighorn sheep in the Sierra Nevada carry Protostrongylus species 
(lungworms), but the parasite loads have been low, and there has been 
no evidence of any clinical signs of disease or disease transmission 
(Wehausen 1979; Richard Perloff, Inyo National Forest, pers. comm. 
    Currently, domestic sheep grazing allotments are permitted by the 
FS in areas adjacent to Sierra Nevada bighorn sheep subpopulations. 
Domestic sheep occasionally escape the allotments and wander into 
bighorn sheep areas, sometimes coming into direct contact with bighorn 
sheep (Advisory Group 1997). For example, in 1995, 22 domestic sheep 
that were permitted on FS land wandered away from the main band and 
were later found in Yosemite National Park, after crossing through 
occupied bighorn sheep habitat (Advisory Group 1997; Bonny Pritchard, 
Inyo National Forest, pers. comm. 1999; R. Perloff, pers. comm. 1999). 
Other stray domestic sheep, in smaller numbers, have been known to 
wander up the road in Lee Vining Canyon into bighorn sheep habitat (B. 
Pritchard, pers. comm. 1999). 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 Sierra Nevada bighorn sheep until the potential for contact 
with domestic sheep is eliminated.
    Predators such as coyote (Canis latrans), bobcat (Lynx rufus), 
mountain lion, gray fox (Urocyon cinereoargenteus), golden eagle 
(Aquila chrysaetos), and free-roaming domestic dogs prey upon bighorn 
sheep (Jones 1950; Cowan and Geist 1971). Predation generally has an 
insignificant effect except on small populations such as the Sierra 
Nevada bighorn sheep. Coyotes are the most abundant large predator 
sympatric (occurring in the same area) with bighorn sheep populations 
(Bleich 1999), and are known to have killed young Sierra Nevada bighorn 
sheep (Vernon Bleich, CDFG, pers. comm. 1999). In the late 1980s, 
mountain lion predation of Sierra Nevada bighorn sheep increased 
throughout their range (Wehausen 1996). This trend has continued into 
the 1990s, as evidenced by Table 1.
    Predation by mountain lions probably was a natural occurrence and 
part of the natural balance of this ecosystem. From 1907 to 1963, the 
State provided a bounty on mountain lions; the State also hired 
professional lion hunters for many years. The bounty most likely kept 
the mountain lion population reduced such that bighorn sheep predation 
was rare and insignificant. Between 1963 and 1968, mountain lions were 
managed as a nongame and nonprotected mammal, and take was not 
regulated. From 1969 to 1972, lions were re-classified as game animals. 
A moratorium on mountain lion hunting began in 1972 and lion numbers 
likely increased. In 1986, the species was again classified as a game 
animal, but CDFG hunting recommendations were challenged in court in 
1987 and 1988 (Tories et al. 1996). In 1990, a State-wide ballot 
initiative (Proposition 117) passed into law prohibiting the killing of 
mountain lions except if humans, or their pets or livestock are 
threatened. Another ballot measure, Proposition 197, which would have 
modified current law regarding mountain lion management failed to pass 
in 1996, largely because of the public's concern that the change may 
allow mountain lion hunting (Tories et al. 1996). With the removal of 
the ability to control the mountain lion population, lion predation 
became a significant

[[Page 26]]

limiting factor on Sierra Nevada bighorn sheep.
    The increased presence of mountain lions appears to have changed 
Sierra Nevada bighorn sheep winter habitat use patterns. Wehausen 
(1996) looked at mountain lion predation in two bighorn sheep 
subpopulations, one in the Granite Mountains of the eastern Mojave 
Desert, and the other in the Mount Baxter subpopulation in the Sierra 
Nevada. He found that the lions reduced the subpopulation in the 
Granite Mountains to eight ewes between 1989 and 1991, and held it at 
that level for 3 years, after which lion predation decreased and the 
bighorn sheep subpopulation increased at 15 percent per year for 3 
years. All the mortality in that subpopulation was attributed to 
mountain lion predation. The Mount Baxter bighorn sheep subpopulation 
abandoned its winter ranges, presumably due to mountain lion predation. 
Forty-nine sheep were killed by lions on their winter range between 
1976 and 1988 out of an average subpopulation size of 127 sheep. These 
mortalities from mountain lion predation represented 80 percent of all 
mortality on the winter range, and 71 percent for all ranges used. 
Evidence also indicates that many of the bighorn sheep killed were 
prime-aged animals (J. Wehausen, pers. comm. 1999).
    The bighorn sheep on Mount Baxter may have moved to higher 
elevations to evade lions. By avoiding the lower terrain and 
consequently the higher quality forage present during the spring, sheep 
emerged from the winter months in poorer condition. Consequences from 
the change in habitat use resulted in a decline in the Baxter 
subpopulation due to decreased lamb survival, because lambs were born 
later and died in higher elevations during the winter. This may have 
also been the case with the Lee Vining subpopulation decline; bighorn 
sheep may have run out of fat reserves at a time when they should have 
been replenishing their reserves with highly nutritious forage from low 
elevation winter ranges. We believe that because of the winter habitat 
shift by the bighorn sheep, the Mount Baxter subpopulation has declined 
significantly. With the large decline of bighorn sheep on Mount Baxter, 
the total population of Sierra Nevada bighorn sheep has now dropped 
below what existed during implementation of the restoration program 
between 1979 and 1988 (Wehausen 1996; Advisory Group 1997), which 
transplanted sheep back into historical habitat. In a 1996 survey on 
Mount Williamson, there was no evidence of groups of sheep, and this 
subpopulation was the last one found using its low-elevation winter 
range in 1986. Mountain lion predation may have led to the extirpation 
of this subpopulation, one of the last two native subpopulations of 
Sierra Nevada bighorn sheep (Wehausen 1996; J. Wehausen, pers. comm. 
    In 1998 and 1999, few mountain lions were documented using the 
Wheeler Crest subpopulation winter habitat. As a result, this 
subpopulation returned to its winter range, and 15 lambs were born to 
the subpopulation in 1998 and again in 1999. The Langley subpopulation 
continues to avoid its winter habitat, presumably due to the presence 
of mountain lions there. As a result, the ewes were in very poor 
condition in the spring and had not recovered to good condition by 
August 1999. One sheep was documented to have been killed by a mountain 
lion in 1999 (J. Wehausen, pers. comm. 1999).
    On September 16, 1999, California enacted legislation (Assembly 
Bill 560) amending Proposition 117 allowing the CDFG to remove or take 
mountain lions that are perceived to be a threat to the survival of any 
threatened, endangered or fully protected sheep species (Diana Craig, 
FS, in litt. 1999; Office of the Governor 1999). Passage of this bill 
will help manage mountain lion predation on Sierra Nevada bighorn 
sheep, but likely will not eliminate this threat. The authority of the 
State to manage mountain lion predation under this law is limited and 
has not yet been fully tested. For example, the law allows the State to 
take mountain lions perceived to be an immediate threat to protected 
bighorn sheep. However, it is not clear that this authority extends to 
removing lions whose presence at lower elevation, winter sheep habitat 
precludes normal, seasonal, bighorn sheep migration patterns. The 
ability to migrate to these lower elevation areas for winter use is 
considered crucial to improving the productivity rate of bighorn sheep 
    The Sierra Nevada bighorn sheep restoration program, implemented 
between 1979 to 1988 to reintroduce the sheep into historical habitat, 
used the Mount Baxter subpopulation as the source of reintroduction 
stock. The three reintroduced subpopulations at Lee Vining Canyon, 
Wheeler Crest, and Mount Langley all suffered from mountain lion 
predation shortly after translocation of sheep (Wehausen 1996). The Lee 
Vining Canyon subpopulation lost a number of sheep to mountain lion 
predation, threatening the success of the reintroduction effort (Chow 
1991, cited by Wehausen (1996)). The subpopulation was supplemented 
with additional sheep, and the State removed one mountain lion each 
year for 3 years, which helped reverse the decline of this 
subpopulation (Bleich et al. 1991 and Chow 1991, cited by Wehausen 
(1996)). Also, because domestic sheep are preyed upon by mountain 
lions, livestock operators who have a Federal permit to graze their 
sheep on FS land can get a depredation permit from the State, and have 
the U.S. Department of Agriculture, Wildlife Services, remove the 
mountain lion. The Lee Vining Canyon subpopulation occurs in the 
general area where domestic sheep are permitted, and has benefitted 
from the removal of mountain lions that were preying on domestic sheep 
(B. Pritchard, pers. comm. 1999). However, this subpopulation has 
continued to decline, and in 1999, only one reproductive ewe remains 
(J. Wehausen, pers. comm. 1999).

D. The Inadequacy of Existing Regulatory Mechanisms

    In response to a very rapid decline in population numbers, in 1876 
the State legislature amended an 1872 law that provided seasonal 
protection for elk, deer and pronghorn to include all bighorn sheep. 
Two years later, this law was amended, establishing a 4-year moratorium 
on the taking of any pronghorn, elk, mountain sheep or female deer. In 
1882, this moratorium was extended indefinitely for bighorn sheep 
(Wehausen et al. 1987). In 1971, California listed the California 
bighorn sheep as ``rare.'' The designation was changed to 
``threatened'' in 1984 to standardize the terminology of the amended 
California Endangered Species Act (CESA) (Advisory Group 1997). The 
California Fish and Game Commission upgraded the species' status to 
``endangered'' in 1999 (Mammoth Times 1999; San Francisco Chronicle 
1999; CDFG 1999). 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, and to allow take incident to 
otherwise lawful activities.
    The policy of the State of California is to protect and preserve 
all native species and their habitat, such as the Sierra Nevada bighorn 
sheep, that are threatened by extinction or are experiencing a 
significant decline that, if not halted, would lead to a threatened or 
endangered designation (California Fish and Game Commission 1999). 
However, the Sierra Nevada bighorn sheep occurs mainly on Federal lands 
administered by the BLM and the FS.

[[Page 27]]

These Federal agencies are responsible for regulating activities on 
Federal lands that may adversely affect bighorn sheep. For example, the 
State alone cannot effectively address disease transmission from 
domestic sheep to Sierra Nevada bighorn sheep because the State does 
not regulate grazing on Federal lands.
    Since the Sierra Nevada bighorn sheep was listed by the State of 
California in 1971, the CDFG has undertaken numerous efforts for the 
conservation of the sheep, including but not limited to--(1) intensive 
field studies; (2) reestablishment of three additional subpopulations 
in historical habitat; (3) creation, in 1981, of the Sierra Nevada 
Bighorn Sheep Interagency Advisory Group, including representatives 
from Federal, State, and local resource management agencies, which has 
produced the Sierra Nevada Bighorn Sheep Recovery and Conservation Plan 
(1984) and a Conservation Strategy for Sierra Nevada Bighorn Sheep 
(1997); and (4) culling four mountain lions that were taking Sierra 
Nevada bighorn sheep, which played a significant role in the efforts to 
reestablish one subpopulation (Chow 1991, cited by Wehausen (1996)).
    Mountain lion hunting has not occurred in California since 1972 
(Tories et al. 1996). As a result of passage of Proposition 117 in 1990 
prohibiting the hunting or control of mountain lions, the CDFG lost the 
authority to remove mountain lions to protect the Sierra Nevada bighorn 
sheep and secure their survival. However, in September of 1999, 
California passed legislation (A. B. 560) allowing the CDFG to take or 
remove mountain lions that are a threat to the Sierra Nevada bighorn 
sheep populations (D. Craig, in litt. 1999; Office of the Governor 
1999). We believe that this law will help eliminate the threat due to 
mountain lion predation, but will likely not completely eliminate it. 
In addition, this legislation was enacted so recently that little time 
has passed to allow us to evaluate its effectiveness as a regulatory 
    Federal agencies have authority to manage the land and activities 
under their administration to conserve the bighorn sheep. Federal 
agencies are taking steps to enhance habitat through prescribed burning 
to improve forage and maintain open habitat, and to retire domestic 
sheep allotments that run adjacent to bighorn sheep habitat. For 
example, the FS burned 263 hectares (ha) (650 acres (ac)) in 1997 in 
Lee Vining Canyon to reduce mountain lion hiding cover, and there are 
plans to do more burns in other areas on FS land (R. Perloff, pers. 
comm. 1999). However, in some cases, because of conflicting management 
concerns, conservation efforts are not proceeding as quickly as 
necessary. Although efforts have been underway for many years, the FS 
has been unable to eliminate the known threat of contact between 
domestic sheep and the Sierra Nevada bighorn sheep by either 
eliminating adjacent grazing allotments, or modifying allotments such 
that a sufficient buffer zone exists that would prevent contact between 
wild and domestic sheep.
    In 1971, the State, in cooperation with the FS, established a 
sanctuary for the Mount Baxter and Mount Williamson subpopulation of 
Sierra Nevada bighorn sheep and called it the California Bighorn Sheep 
Zoological Area (Zoological Area) (Wehausen 1979; Inyo National Forest 
Land Management Plan (LMP) 1988). The FS set aside about 16,564 ha 
(41,000 ac) of FS land for these two subpopulations. At the time, many 
felt that the species' decline was related to human disturbance. The 
sanctuary was designed to regulate human use in some areas (Hicks and 
Elder 1979), and reduce domestic sheep/wild sheep interaction by 
constructing a fence below the winter range of the Mount Baxter 
subpopulation along the FS and BLM boundary (Wehausen 1979). Adjacent 
summer range on NPS land was also given a restrictive designation to 
reduce human disturbance (Wehausen 1979). The FS continues to manage 
the Zoological Area; it encompasses land designated as wilderness and 
mountain sheep habitat (LMP 1988; R. Perloff, pers. comm. 1999).
    Despite the establishment of the sanctuary, the sheep population 
has continued to decline. This decline is most likely due to mountain 
lion predation and the abandonment of low elevation winter range 
(Wehausen 1996). Also, the sanctuary fence was constructed only at the 
mouth of the canyon where the Mount Baxter herd winters, adjacent to a 
stock driveway used to drive domestic sheep towards their summer 
grazing allotments on Federal land further north (B. Pritchard, pers. 
comm. 1999). The fence does not prevent domestic sheep from leaving 
their bands while on the grazing allotments and moving into habitat 
used by Sierra Nevada bighorn sheep.

E. Other Natural or Manmade Factors Affecting its Continued Existence

    The Sierra Nevada bighorn sheep population is critically small with 
a total of only 125 sheep known from 5 subpopulations. There is no 
known interaction between the separate subpopulations. The Sierra 
Nevada bighorn sheep currently is highly vulnerable to extinction from 
threats associated with small population size and naturally occuring 
    Although inbreeding depression has not been demonstrated in the 
Sierra Nevada bighorn sheep, the number of sheep occupying all areas is 
critically low. The minimum size at which an isolated group of this 
species 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). Small populations are extremely 
susceptible to chance variation in age and sex ratios or other 
population parameters (demographic stochasticity) and genetic problems 
(Caughley and Gunn 1996). Small populations suffer higher extinction 
probabilities from chance events such as skewed sex ratio of offspring, 
(e.g., fewer females being born than males). For example, the Mount 
Langley subpopulation has been declining. In 1996-97, out of a 
subpopulation of 4 ewes and 10 rams, 5 lambs were born, of which 4 were 
female. Although a positive event for this subpopulation, it could have 
been devastating if the female:male ratio had been reversed (J. 
Wehausen, pers. comm. 1999).
    The five subpopulations include a total of nine female demes (i.e., 
local populations). These demes are defined by separate geographic home 
range patterns of the females. Three of these demes appear not to use 
low elevation winter ranges at all, and they will probably go extinct 
as a result (J. Wehausen, pers. comm. 1999). For example, the Black 
Mountain deme, consisting of five ewes, was previously part of the Sand 
Mountain deme, which also has five ewes and is part of the Mount Baxter 
subpopulation. The Black Mountain deme became a separate deme after 
winter range abandonment in the late 1980s, and does not appear to know 
of the Sand Mountain winter range, which lies considerably north of 
their home range. This deme has shown a steady decline in size (J. 
Wehausen, pers. comm. 1999).
    There are six female demes that may persist, but all are still very 
vulnerable to extinction due to small size. With the likely extinction 
of some of the existing demes, the remaining demes become all the more 
important to the persistence of this distinct population segment, and 
each remaining female is critically important to her deme. Individual 
mountain lions can do enormous

[[Page 28]]

damage to any of these small demes, as can catastrophic events such as 
snow avalanches.
    We also do not know the current distribution of genetic variation 
among all of these subpopulations. Each subpopulation likely has lost 
some genetic variability, thereby reducing its ability for long-term 
adaptation. The ultimate goal of conserving this DPS must be to 
preserve as much of its genetic variation a possible. It is likely that 
all or some of the existing demes now contain some variation not 
represented in others. Until some measure of the distribution of 
genetic variation exists, every deme should be considered a significant 
portion of the overall population. Maintenance of genetic variability 
requires the preservation of rams in addition to ewes.
    Small, isolated groups are also subject to extirpation by naturally 
occurring random environmental events (e.g., prolonged or particularly 
heavy winters and avalanches). In 1995, for example, a dozen sheep died 
in a single avalanche at Wheeler Crest (J. Wehauser, pers. comm. 1999). 
Such threats are highly significant because the subpopulations are 
small and it is also common in bighorn sheep for all members of one sex 
to occur in a single group. During the very heavy winters in the late 
1970s and early 1980s, there was no notable mortality in the 
subpopulations because they were using low elevation winter ranges (J. 
Wehausen, pers. comm. 1999).
    Competition for critical winter range resources can occur between 
bighorn sheep and elk and/or deer (Cowan and Geist 1971). However, 
competition between these species does not appear significant since 
deer and bighorn sheep readily mix on winter range, and the habitat 
overlap between elk and bighorn sheep is slight (Wehausen 1979).
    In addition to disease, mountain lion predation, and naturally 
occurring events, other factors may contribute to bighorn sheep 
mortality. For example, two subpopulations (Wheeler Crest and Lee 
Vining) have ranges adjacent to paved roadways, exposing individuals 
from those subpopulations to potential hazards. Bighorn sheep have been 
killed by vehicles in Lee Vining Canyon on several occasions (V. 
Bleich, pers. comm. 1999).
    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
faced by this species in developing this final rule. All five 
subpopulations of the Sierra Nevada distinct population of California 
bighorn sheep are imperiled by disease, predation, naturally occurring 
environmental events, and the continual loss of genetic variation if 
the subpopulations remain small. The Sierra Nevada bighorn sheep 
population reached a high of about 310 in 1985-86, but subsequent 
population surveys have documented a declining trend. Currently, only 
about 125 animals exist. The potential for contact with domestic sheep 
and the transmission of disease could, by itself, eliminate an entire 
deme. Domestic sheep continue to stray into Sierra Nevada bighorn sheep 
habitat and come into close proximity to the resident bighorn sheep on 
numerous occasions. However, domestic sheep have not come into contact 
with bighorn sheep during these events. Vulnerability to demographic 
problems must be viewed as a combination of immediate threats of 
predation, changed habitat use due to the presence of mountain lions, 
the resultant decline of ewe nutrition and lamb survivorship, exposure 
to environmental catastrophes, and the transmission of disease from 
domestic sheep. Because of the high potential for these threats to 
result in the extinction of this bighorn sheep distinct population 
segment, it warrants listing as endangered. Immediately upon 
publication, this final rule will continue the protection for this DPS 
of California bighorn sheep, which began when we emergency listed this 
DPS on April 20, 1999.

Critical Habitat

    In the emergency rule, we indicated that designation of critical 
habitat was not determinable for the Sierra Nevada bighorn sheep due to 
a lack of information sufficient to perform the required analysis of 
impacts of the designation. We have re-examined the question of whether 
critical habitat is not determinable, and have determined that there is 
sufficient information to do the required analysis.
    In the absence of a finding that critical habitat would increase 
threats to a species, if there are any benefits to critical habitat 
designation, then a prudent finding is warranted. In the case of this 
species, there may be some benefits to designation of critical habitat. 
The primary regulatory effect of critical habitat is the section 7 
requirement that Federal agencies refrain from taking any action that 
destroys or adversely modifies critical habitat (see Available 
Conservation Measures section) . While a critical habitat designation 
for habitat currently occupied by this species would not likely change 
the section 7 consultation outcome, because an action that destroys or 
adversely modifies such critical habitat would also be likely to result 
in jeopardy to the species, there may be instances where section 7 
consultation would be triggered only if critical habitat is designated. 
Examples could include unoccupied habitat or occupied habitat that may 
become unoccupied in the future. There may also be some educational or 
information benefits to designating critical habitat. We find that 
critical habitat is prudent for the Sierra Nevada bighorn sheep.
    Our Final Listing Priority Guidance for FY 2000 (64 FR 57114) 
states that the processing of critical habitat determinations (prudency 
and determinability decisions) and proposed or final designations of 
critical habitat will no longer be subject to prioritization under the 
Listing Priority Guidance. Critical habitat determinations, which were 
previously included in final listing rules published in the Federal 
Register, may now be processed separately, in which case stand-alone 
critical habitat determinations will be published as notices in the 
Federal Register. We will undertake critical habitat determinations and 
designations during FY 2000 as allowed by our funding allocation for 
that year.'' As explained in detail in the Listing Priority guidance, 
our listing budget is currently insufficient to allow us to immediately 
complete all of the listing actions required by the Act. Deferral of 
the critical habitat designation for the Sierra Nevada bighorn sheep 
will allow us to concentrate our limited resources on higher priority 
critical habitat and other listing actions, while allowing us to put in 
place protections needed for the conservation of the Sierra Nevada 
bighorn sheep without further delay. However, because we have 
successfully reduced, although not eliminated, the backlog of other 
listing actions, we anticipate in FY 2000 and beyond giving higher 
priority to critical habitat designation, including designations 
deferred pursuant to the Listing Priority Guidance, such as the 
designation for this species, than we have in recent fiscal years.
    We plan to employ a priority system for deciding which outstanding 
critical habitat designations should be addressed first. We will focus 
our efforts on those designations that will provide the most 
conservation benefit, taking into consideration the efficacy of 
critical habitat designation in addressing the threats to the species, 
and the magnitude and immediacy of those threats. We will develop a 
proposal to designate critical habitat for the Sierra Nevada bighorn 
sheep as soon as feasible, considering our workload

[[Page 29]]

priorities. For the immediate future, most of Region 1's listing budget 
must be directed to complying with numerous court orders and settlement 
agreements, as well as due and overdue final listing determinations.

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, 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 Act are codified at 50 CFR part 402. If a 
species is 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 designated critical habitat. If a Federal agency 
action may affect a listed species or its critical habitat, the 
responsible Federal agency must enter into formal consultation with us. 
Federal agency actions that may require conference and/or consultation 
include those within the jurisdiction of the FS, BLM, and NPS.
    We believe that protection of the Sierra Nevada bighorn sheep 
requires reduction of the threat of mountain lion predation, 
particularly during the months of April and May when bighorn sheep 
attempt to use low elevation winter ranges to obtain necessary 
nutrition after lambing, and ewes and lambs are most vulnerable to 
predation. California's recently enacted legislation (A. B. 560) 
allowing removal of mountain lions that threaten Sierra Nevada bighorn 
sheep will reduce this threat. Removal of mountain lions may not 
necessarily involve lethal techniques.
    We believe that protection of the Sierra Nevada bighorn sheep also 
requires reduction of the threat of disease transmission from domestic 
sheep by preventing domestic sheep from coming into contact with 
bighorn sheep. We will work with the FS to reduce the threat of disease 
transmission by domestic sheep. Reduction of this threat may involve 
elimination of grazing allotments adjacent to bighorn sheep habitat, or 
modifying allotments to create a sufficient buffer zone that would 
prevent contact between domestic sheep and bighorn sheep.
    Listing this species would provide for the development of a 
recovery plan. Such a plan would bring together both State and Federal 
efforts for the conservation of the species. The plan would establish a 
framework for agencies to coordinate activities and cooperate with each 
other in conservation efforts. The plan would set recovery priorities 
and estimate costs of various tasks necessary to accomplish them. It 
also would describe site-specific management actions necessary to 
achieve conservation and survival of the Sierra Nevada bighorn sheep. 
Additionally, pursuant to section 6 of the Act, we would be able to 
grant funds to affected states for management actions promoting the 
protection and recovery of this species.
    The Act and implementing regulations found at 50 CFR 17.21 set 
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 endangered animal 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 our agents 
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. 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 our policy, published in the Federal Register on July 1, 1994 
(59 FR 34272), to identify to the maximum extent practicable at the 
time a species is listed those activities that likely 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 we 
believe will likely result in a violation of section 9 include, but are 
not limited to:
    (1) Unauthorized trapping, capturing, handling or collecting of 
Sierra Nevada bighorn sheep. Research activities involving trapping or 
capturing of Sierra Nevada bighorn sheep will require a permit under 
section 10(a)(1)(A) of the Act.
    (2) Failure to confine livestock to authorized grazing allotments 
resulting in transmission of disease or habitat destruction.
    Activities we believe will not likely 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 Sierra Nevada bighorn 
sheep that were collected prior to April 20, 1999, the date of 
publication of the emergency listing rule in the Federal Register;
    (2) Normal, legal recreational activities in designated campsites 
or recreational use areas, and on authorized trails.
    Direct your questions regarding any specific activities to our 
Ventura Fish and Wildlife 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 (telephone 503/231-2063; 
facsimile 503/231-6243).

National Environmental Policy Act

    We have determined that an environmental assessment or 
environmental impact statement, as defined under the National 
Environmental Policy Act of 1969, need not be prepared in connection 
with regulations adopted pursuant to section 4(a) of the Act. We 
published a notice outlining our reasons for this determination in the 
Federal Register on October 25, 1983 (48 FR 49244).

Paperwork Reduction Act

    This rule does not contain any information collection requirements 
for which Office of Management and Budget (OMB) approval under the 
Paperwork Reduction Act, 44 U.S.C. 3501 et seq. is required. An 
information collection related to the rule pertaining to permits for 
endangered and

[[Page 30]]

threatened species has OMB approval and is assigned clearance number 
1018-0094. An agency may not conduct or sponsor, and a person is not 
required to respond to, a collection of information unless it displays 
a currently valid control number. This rule does not alter that 
information collection requirement. For additional information 
concerning permits and associated requirements for endangered wildlife, 
see 50 CFR 17.22.

References Cited

    A complete list of references cited in this rule is available upon 
request from the Ventura Fish and Wildlife Office of the U.S. Fish and 
Wildlife Service (see FOR FURTHER INFORMATION CONTACT section).
    Authors. The primary authors of this final rule are Carl Benz, 
Ventura Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT 
section), and Barbara Behan, Regional Office, 911 N.E. 11th Avenue, 
Portland, Oregon 97232 (telephone 503/231-6131).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Regulation Promulgation

    Accordingly, we amend part 17, subchapter B of chapter I, title 50 
of the Code of Federal Regulations, as follows:


    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) * * *

                        Species                                                    Vertebrate
--------------------------------------------------------                        population where                                  Critical     Special
                                                            Historic range       endangered or         Status      When listed    habitat       rules
           Common name                Scientific Name                              threatened

                   *                  *                  *                  *                  *                  *                  *

                   *                  *                  *                  *                  *                  *                  *
Sheep, Sierra Nevada bighorn.....  Ovis canadensis       U.S.A. (western      U.S.A., CA-Sierra    E                      660E           NA           NA
                                    californiana.         conterminous         Nevada.                                     675
                                                          states), Canada
                                                          Mexico (north).

                   *                  *                  *                  *                  *                  *                  *

    Dated: December 22, 1999.
Jamie Rappaport Clark,
Director, Fish and Wildlife Service.
[FR Doc. 99-34056 Filed 12-30-99; 8:45 am]