Sierra Nevada Bighorn Sheep (Ovis canadensis sierrae) is a subspecies of Bighorn Sheep. The assignment of Bighorn Sheep populations to this subspecies is currently controversial. Early taxonomic schemes included herds from British Columbia to southern California in a broader subspecies Ovis canadensis californiana. More recent genetic testing has indicated that O. c. californiana consists of only a small population located in the southern and central Sierra Nevada, hence should be renamed Ovis canadensis sierrae.

The Sierra Nevada Bighorn Sheep listed as an endangered species on January 3, 2000, following emergency listing on April 20, 1999. In 1995, these genetically distinct Bighorn Sheep hit a population low of about 100 total individuals, distributed across 5 separate areas of the southern and central Sierra Nevada, and had increased to about 125 in 1999. Since then conditions have been particularly favorable for population growth, with the total number of individuals reaching about 250 as of 2002.. These desert bighorn sheep use habitats ranging from the highest elevations along the crest of the Sierra Nevada (4,000+ meters [13,120+ feet]) to winter ranges at the eastern base of the range as low as 1,450 meters (4,760 ft). Significant population declines beginning in the late 1980s were associated with these desert bighorn sheep avoiding low elevation winter ranges.

The Nevada Department of Wildlife estimates that there are 1500 California Bighorn Sheep located in northwestern Nevada as of 2004. However this population appears to be genetically distinct from the Sierra Nevada population, and may be more properly classified as Desert Bighorn Sheep (O. c. nelsoni).

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