[Federal Register Volume 64, Number 189 (Thursday, September 30, 1999)]
[Proposed Rules]
[Pages 52757-52758]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-25466]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AF59


Endangered and Threatened Wildlife and Plants; Reopening of the 
Comment Period on the Proposed Endangered Status of the Sierra Nevada 
Distinct Population Segment of the California Bighorn Sheep

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; notice of reopening of comment period.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), pursuant to 
the Endangered Species Act of 1973, as amended (Act), provide notice of 
the reopening of the comment period for the proposed endangered status 
for the Sierra Nevada distinct population segment of California bighorn 
sheep (Ovis canadensis californiana). The comment period has been 
reopened in response to a request from the Foundation for North 
American Wild Sheep and to conduct a peer review of the proposed rule.

DATES: Comments from all interested parties must be received by October 
15, 1999.

ADDRESSES: Written comments, materials, data, and reports concerning 
this proposal should be sent to the Supervisor, Ventura Fish and 
Wildlife Office, 2493 Portola Road, Suite B, Ventura, California 93003. 
Comments and materials received will be available for public 
inspection, by appointment, during normal business hours, at the above 
address.

FOR FURTHER INFORMATION CONTACT: Carl Benz, at the address listed above 
(telephone 805/644-1766; facsimile 805/644-3958).

SUPPLEMENTARY INFORMATION:

Background

    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

[[Page 52758]]

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 are 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 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 in males, and are smaller and not coiled in 
females (Jones 1950; Buechner 1960). As the animals age, their horns 
become rough and scarred with age, 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 a 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, Bureau of Land Management, and National Park Service. The 
Sierra Nevada is located along the eastern boundary of California, and 
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).
    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 show 
some predictable patterns that consists of feeding and resting periods 
(Jones 1950). Bighorn sheep are inherently 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.
    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 two 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.
    All five subpopulations of this species are threatened by mountain 
lion (Puma concolor) predation, disease, and random, naturally-
occurring events.
    We published an emergency rule to list the Sierra Nevada distinct 
population segment of California bighorn sheep as endangered on April 
20, 1999 (64 FR 19300), as well as a proposed rule to list the species 
as endangered on that same date (64 FR 19333). The original comment 
period closed on June 21, 1999. In a memo dated June 16, 1999, the 
Foundation for North American Wild Sheep requested that the comment 
period be extended to allow us to consider additional information 
regarding the Sierra Nevada bighorn sheep. In addition, we will also 
conduct a peer review of this proposal and solicit the opinions of 
three appropriate and independent specialists regarding the data, 
assumptions, and supportive information presented for the Sierra Nevada 
bighorn sheep, per our Interagency Cooperative Policy for Peer Review 
in Endangered Species Act Activities (59 FR 34270).

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 ADDRESSES section).

Author

    The primary author of this notice is Barbara Behan of the Regional 
Office, U.S. Fish and Wildlife Service, 911 N.E. 11th Avenue, Portland, 
Oregon 97232-4181 (telephone 503/231-6131).

Authority

    The authority of this action is the Endangered Species Act of 1973, 
as amended (16 U.S.C. 1531 et seq.).

    Dated: September 24, 1999.
Elizabeth H. Stevens,
Acting Manager, California/Nevada Operations Office, Fish and Wildlife 
Service.
[FR Doc. 99-25466 Filed 9-29-99; 8:45 am]
BILLING CODE 4310-55-P