The peninsular bighorn sheep (Ovis canadensis pop. 2) is restricted to east facing, lower elevation slopes (typically below 4,600 feet) of the Peninuslar Ranges along the northwest edge of the Sonoran Desert in southern California. Though populations occur in Mexico, the species is only listed as endangered from the San Jacinto Mountains south to the U.S.-Mexico border. It has declined due to its habitat being developed for housing and agriculture, car collisions, predation by mountain lions, diseases contracted from domestic sheep, disturbance by humans and dogs, fire suppression, and spread of exotic plants such as tamarisk .
The historic population size is unknown, but the species was considered "rare" in 1971 when it was estimated at 971 animals . The species highest recent population was 1,171 in 1974 and 1979. It plummeted to 276 in 1996 and increased to 705 in 2004 [1, 2]. A rash of deaths, apparently from disease, struck the species in 2005. As of September 2005, the magnitude of the impact is unknown.
Approximatley 100 peninsular bighorn are captive bred and used to augment the wild population .
 USFWS. 2000. Recovery Plan for bighorn sheep in the Peninsular Ranges, California. United States Fish and Wildlife Service, Portland, OR. 251 pp.
 Bighorn Institute. 2005. Endangered Peninsular Bighorn Sheep, website (www.bighorninstitute.org/endangered.htm) accessed September 30, 2005.