California Department of Fish and Wildlife

Sierra Nevada Bighorn Sheep Progress Towards Recovery

Sierra Nevada bighorn sheep are an endangered species under Federal law and California law. There is a real opportunity to recover Sierra bighorn because the habitat is intact and there is broad public and agency support for the effort. Sierra bighorn are one of only two only federal endangered species in Yosemite National Park and Sequoia-Kings Canyon National Parks(along with the mountain yellow-legged frog ); these parks are excited to see this iconic mammal restored as part of the native fauna within their boundaries. Down-listing goals can be met in the next decade if recovery actions are implemented. Translocations to augment newly created herd units are still needed while the existing herds that serve as translocation stock must be protected.

Population Growth for Each Herd Unit (Ewes)

In bighorn sheep, the number of adult ewes determines how quickly a population can grow or recover from losses. Because of this, the health of a population is often gauged by the number of ewes present. This graph shows population trajectories for adult and yearling females from 1999-2015 based on a combination of population estimates (marked resight and minimum count) for 6 herds in the Sierra with annual population data.

SNBS Herd Unit Size Ewes

Numerical Recovery Goals

The population goal for downlisting to threatened status is 305 females (>1 year).

SNBS Recovery Units and Herd Units



The population must be distributed among 12 of 16 herd units within the 4 recovery units. For delisting the required number of bighorn sheep must persist for a minimum of 7 years without management intervention. Currently, all 12 of the 12 required units have bighorn sheep, as do 2 of the non-required herd units and over 300 females were observed in 2015 of the 305 required (85% of goal).

SNBS Recovery Units and Population Estimates



The numerical and herd unit / recovery unit occupation is tabularly summarized below. Achieving final recovery goals will require an additional number of translocations and augmentations, currently planned at 30-40 ewes. These ewes will likely be supplied by the Mt. Langley, Mt. Baxter, Sawmill Canyon and Wheeler Ridge herds. Therefore, surplus animals must be available for removal from these herds.(see map of herds)

Recovery Unit Herd Unit Recovery Plan
Downlisting / Delisting
Criteria
Recovery Unit #Ewes
Current Population
Recovery Unit
(2015)
Ewes > 1 yr
Current Population
Herd Unit
(2015)
Ewes > 1 yr
Plan to Achieve
Numerical Goals
Kern Laurel Creek* 50 16 7 Translocation
Big Arroyo* 9 Translocation
Southern Olancha Peak* 155 156 14 Natural growth
Mt. Langley* 40 Natural growth
Mt. Willamson* 12 Natural growth
Bubbs Creek** 12 Natural growth
Mt. Baxter* 40 Natural growth
Sawmill Canyon* 35 Natural growth
Taboose Creek* 3 Natural growth
Black Divide 0 Translocation
Coyote Ridge 0 Translocation
Central Wheeler Ridge* 50 65 52 Natural growth
Convict Creek* 13 Natural growth
Northern Mt.Gibbs* 50 38 17 Natural growth
Mt. Warren* 11 Natural growth
Green Creek 0  
Twin Lakes 0  
Cathedral Range** 10 Translocation
Key
  *         Required, currently occupied
  **       Not Required, currently occupied