[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
