Sierra Nevada Bighorn Sheep

SCIENTIFIC NAME: Ovis canadensis californiana

STATUS: Endangered

HABITAT: Steep, rocky alpine slopes

LIFE HISTORY: Migrates from elevations of approximately 5,000 feet in winter to 11,000 feet or higher in summer. Unable to outrun most predators; stocky build and short legs allow for great agility, which permits escape.

THREATS: Disease from domestic livestock; excessive predation

FORMER RANGE: Central and southern Sierra Nevada

CURRENT POPULATION: 350 to 400 individuals

Naturalist John Muir called this stocky sheep "the bravest of all the Sierra mountaineers." The Sierra Nevada Bighorn uses its extraordinary agility to escape predators, scampering up impossibly steep, rocky slopes and bounding from crag to crag.

The bighorn's agility does not, however, help it escape a fatal pneumonia that it can contract from domestic sheep. When settlers started grazing domestic sheep in the Sierras in the mid-19th century, bighorns fell into a steep decline. And more recently, their numbers were further threatened by a surging population of mountain lions, which are protected under California state law. In 1998, only about 100 adults remained in the Sierra Nevada.

NRDC filed the petition that resulted in the sheep's emergency listing as an endangered species in 1999, and its formal listing in 2000. Under Endangered Species Act protections, bighorns have mounted a comeback. The state of California now employs trackers to warn mountain lions away from bighorn herds, and NRDC is working to close domestic sheep grazing allotments that are key to the survival of wild sheep in Sierra national forests. The bighorn population is still precarious, and NRDC continues to monitor threats to the wild sheep's survival and push the Fish and Wildlife Service to designate all of the critical habitat essential to the bighorn's needs.

Photos: Muir Woods © National Park Service; coastal California gnatcatcher © Arnold Small, USFWS; Sierra Nevada bighorn © CA Dept. Fish & Game; California condor © Scott Frier/Nikon, USFWS; southern sea otter © NOAA/Dept. of Commerce