Sierra Nevada bighorn are a genetically distinct subspecies of bighorn… (Andrew Hughan / California…)
The newly formed group of Sierra Nevada bighorn sheep barreled up rugged Olancha Peak last month, the 10 females and four males becoming the first new herd of the endangered animals reintroduced in California in 25 years.
Once abundant throughout the region's alpine areas, the state's population of Sierra Nevada bighorn had dwindled to two herds by the 1970s. Their numbers have been devastated by disease spread by contact with domestic sheep and goats and unregulated commercial hunting.
The new herd is a success story for the distinct population of Sierra Nevada sheep, which were listed as endangered in 2000. Since 2007, the California Department of Fish and Wildlife has been working to recover the animals by reestablishing herds in areas identified as containing suitable habitat — rugged, steep mountain slopes ranging from 5,000 feet to 14,000 feet in elevation.
The reintroduction program is designed to disperse the animals across a wide area to give them the best chance to thrive.
"When you recover an endangered species you want to restore as much of the historic range as you can," said Tom Stephenson, a fish and wildlife bighorn recovery program leader.
"You don't want small isolated populations prone to catastrophe. So our recovery goals are both numeric and geographic."
The animals' historic range is now largely protected within five national forests and five national parks, a factor that will provide a buffer and aid in the species' recovery, Stephenson said.
The new herd was released at the southern end of the Sierra range in Inyo County, officials said.
The animals had already been through a lot, having been captured from two of the largest wild herds in the Sierra Nevada and transported by truck to the release site.
There, they were blindfolded to keep them calm, given a medical check and fitted with a wide leather radio collar.
Once the door slid up on the wooden holding crates, the rams bolted away and the ewes waited a moment before bounding out and scooting up the hillside.
There are now 10 herds of Sierra bighorn between Owens Lake and Mono Lake. The state has plans to establish three additional herds to meet recovery goals for the bighorn, which number about 500, up from a low of about 100 animals.
Sierra Nevada bighorn are a genetically distinct subspecies of bighorn sheep, with the rams tending to grow flared, curling horns. The animals are herbivores and spend their days grazing. Bighorn summer in alpine regions and come down to lower elevations in the fall.
Stephenson said that ideally each pack would contain include 20 to 30 females, meaning that in coming years more animals will be released in the same area.
Also last month, six female sheep were moved to become part of two small northern herds in Convict Creek and Mount Gibbs, according to wildlife officials.