Distinguishing
Features
As with the Rocky Mountain Bighorn,
the distinctive feature of California Bighorn Sheep is the massive
brown spiral horns which, in rams, curls back and down close to
the head with tips projecting forward and outward just below the
eyes. The curl is slightly more open than in R.M. Bighorns. The
ewe's horns are shorter and simply curl back laterally from the
crown. The coat is smooth and close to the body contours. The dorsal
colour is dark brown with darker chocolate brown on the chest, face
and legs. The lower belly, backs of the legs, muzzle and large rump
patch are ivory white. Males weigh 130 - 156 kg. Females are much
smaller than males (Banfield, 1974).
Distribution
Columbia Basin: Only found in the
extreme southwestern portion of the Columbia Basin near Grand Forks.
British Columbia: California Bighorn
Sheep have a discontinuous range throughout south central British
Columbia. There is a small, isolated population north of Anahim
Lake. From just north of Williams Lake south, populations inhabit
portions of the Chilcotin and other western tributaries of the Fraser
River. Others occur northwest and northeast of Kamloops, on both
sides of the Okanagan Valley, and in the Ashnola-Similkameen drainage.
There is also a small introduced population near Grand Forks.
Global: O. c. californiana
ranges from the south-central interior of British Columbia to California.
Habitat
California Bighorn Sheep are found
mainly in alpine-desert grasslands associated with mountains, cliffs,
foothills, and river canyons, which offer good escape terrain from
predators. This subspecies prefers areas with low precipitation
levels in winter, at 600 - 1800 m elevation, whereas summer habitat
is found at 2000 - 2500 m in the subalpine and alpine.
Threats
There are thought to be approximately
3700 individuals in British Columbia. Overharvesting has historically
been a threat, but provincial wildlife management and conservation
efforts have controlled this through limited entry hunting and restricted
seasons for full curl rams only. Livestock grazing, interruption
of migration corridors, residential and agricultural development
of winter habitat, and lack of grassland-maintaining fires all potentially
threaten California Bighorn Sheep. Smaller, more isolated populations
are more vulnerable than larger ones.
Biology
This herbivore will often eat grasses and sedges,
but the diet also includes significant amounts of shrubs and forbs.
For most of the year, except the rut, adult males live in groups
often separated from ewes and younger sheep. Mating takes place
between late October and November, followed by gestation of around
175 days. One and rarely two young born in April or May are usually
weaned in 4-6 months (Cannings et al. 1999).
