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RENO FWO: Sierra Nevada Bighorn Sheep Reintroduced into Yosemite, Sequoia National Parks
California-Nevada Offices , May 18, 2015
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Sierra bighorn ewes being released into Yosemite National Park’s Cathedral Range.
Sierra bighorn ewes being released into Yosemite National Park’s Cathedral Range. - Photo Credit: Steve Bumgardner/Yosemite Conservancy for the USFWS
A Sierra bighorn ewe leaps from her transport box and into Yosemite National Park’s Cathedral Range.
A Sierra bighorn ewe leaps from her transport box and into Yosemite National Park’s Cathedral Range. - Photo Credit: Steve Bumgardner/Yosemite Conservancy for the USFWS
Sierra bighorn ewes start exploring their new home in Yosemite National Park’s Cathedral Range.
Sierra bighorn ewes start exploring their new home in Yosemite National Park’s Cathedral Range. - Photo Credit: Steve Bumgardner/Yosemite Conservancy for the USFWS

By Erin Nordin

Bighorn sheep capture-and-release events are always exciting no matter how many times you are lucky enough to participate.  Before the first bighorn sheep arrive at basecamp, almost everyone is quiet – listening for the noise of the helicopter.  The noise from the helicopter signals the arrival of bighorn sheep.  Once everyone sees the helicopter, its precious cargo dangling below it, everyone leaps into action.  

The endangered bighorn sheep that arrived at basecamp in March were a unique subspecies – the Sierra Nevada bighorn sheep or Sierra bighorn (Ovis canadensis sierrae) – which occur only in the Sierra Nevada.  A multiagency effort involving the Service; the California Department of Fish and Wildlife (CDFW); Yosemite, Sequoia, and Kings Canyon National Parks; and Inyo National Forest was reintroducing them to Yosemite and Sequoia National Parks.  This event marks an important milestone in the recovery of Sierra bighorn because the subspecies now occupies all recovery units and herd units considered essential for recovery.  Most importantly, Sierra bighorn occupy a historic portion of their range – in Yosemite National Park – for the first time in more than 100 years!

At one time, Sierra bighorn could be found along the crest of the Sierra Nevada from the Sonora Pass area south to Olancha Peak and even west of the Kern River.  The number of Sierra bighorn before settlement is unknown, but there were likely thousands of animals.  Following immigration of European settlers to the area, the population began to decline.  This decline has been attributed to unregulated hunting and disease spread by livestock, specifically domestic sheep.  

By the 1970s, the population of Sierra bighorn had dwindled to about 250 animals.  These animals made up three populations in just two areas located at the southern end of their range.  In an effort to increase the size and distribution of the population, CDFW began a translocation program in 1979 where Sierra bighorn from existing large populations were reintroduced to areas within its historic range. 

Despite these efforts, threats such as predation by mountain lions decreased the population to about 122 animals by 1999.  In 1999, the CDFW upgraded the status of Sierra bighorn to state endangered and the Service emergency listed it as endangered. 

In 2007, the Service and CDFW finalized the Recovery Plan for the Sierra Nevada Bighorn Sheep.  The ultimate goal of the Recovery Plan is to attain population sizes and geographic distribution that assures the long-term viability of the Sierra bighorn population.  The plan also identified the now-occupied four recovery units and 12 herd units, spanning the historic range of the subspecies, as essential for recovery.

Since listing, recovery efforts led by the California Department of Fish and Wildlife have increased the number of Sierra bighorn to more than 600 animals. 

The story of the Sierra bighorn highlights the success of the Endangered Species Act, but it also demonstrates how many years it can take to recover a listed species.  Even now, there are threats to the persistence of the Sierra bighorn population so it cannot be considered recovered.  However, the tireless work of dedicated state and federal employees, researchers, and nonprofit organizations ensures the path toward recovery. 

 

 -- FWS  --


Erin Nordin is a Service biologist assigned to the Reno Fish and Wildlife Office, working on the Sierra Nevada bighorn sheep project in Bishop, California.

 


Contact Info: Erin Nordin, (760) 872-5020, erin_nordin@fws.gov
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