Bighorn sheep recovery plan released
Submitted by U.S. Fish & Wildlife Service
February 13, 2008, 10:23 AM
The U.S. Fish and Wildlife Service (Service) has completed a cooperative plan to recover the Sierra Nevada Bighorn Sheep to a sustainable level where it can be removed from the federally protected category.
“We strongly believe that a collaborative stewardship approach, involving government agencies and the private sector is critical to achieving the ultimate goal of recovery,” said Steve Thompson, manager of the Service’s California-Nevada Operations Office.
The notice of the availability of the final recovery plan was published in today’s Federal Register. A copy of the recovery plan and other information are available on the Internet at http://www.fws.gov/ventura/newsroom/ by a link within the body of the news release, or by contacting the Ventura Fish and Wildlife Office by telephone at 805/644-1766.
The Sierra Nevada bighorn sheep was listed as endangered on January 3, 2000
following emergency listing on April 20, 1999. As such, it is at risk of extinction throughout all or a significant portion of its range. In 1999, only about 125 bighorn sheep remained in the Sierra Nevada, living in five separate areas on mountainous, federally-owned land primarily in California’s Inyo and Mono counties. Their population has since increased to at least 400 individuals. Even though their habitat is primarily on federal land and is relatively undisturbed, their distribution has been
greatly reduced and fragmented over the past 150 years, which leaves the sheep more vulnerable to extinction.
Sierra Nevada bighorn sheep are large animals that inhabit the east side and crest of the southern and central Sierra Nevada. They are sure-footed and agile with specialized hooves that enable them to easily negotiate steep, rocky terrain. The sheep breed in the fall, and the ewes give birth to one lamb in the spring or early summer.
Diseases spread by domestic sheep beginning in the 1860s coupled with indiscriminate hunting during that time period and possible predation by mountain lions in recent decades are considered the primary reasons for the decline of the bighorn sheep. From February through April, the sheep may be more vulnerable to predators when they attempt to move to lower elevations to forage on new, nutritious plant growth and avoid harsh winter conditions at higher elevation before lambs are born. During the 1980s bighorn sheep began remaining at higher elevations throughout the winter. This behavior led to greater risk of mortality due to exposure, avalanches, and an inadequate food supply, and was followed by a steep population decline. Some believe that when the bighorn sheep herd size gets small, they will remain at higher elevations to avoid predation by mountain lions.
One of the recovery criteria outlined in the plan is to maintain specific population sizes for each recovery unit for seven consecutive years.
Another recovery criteria is to ensure that Sierra Nevada bighorn sheep of both sexes occupy at least two essential herd units in the Kern Recovery Unit, six in the Southern Recovery Unit, two in the Central Recovery Unit, and two in the Northern Recovery Unit. Currently, seven essential and one non-essential herd unit are occupied by Sierra Nevada bighorn sheep. The rest of the units are currently not occupied by the Sierra Nevada bighorn sheep.
One of the actions in the recovery plan for the Sierra Nevada bighorn sheep is protecting them from mountain lions until herd sizes increase sufficiently. The plan calls for removing lions that are a threat while ensuring the viability of the mountain lion population. This temporary measure may help herds obtain forage at lower elevations in late winter, resulting in a boost in the sheep population.
Another criteria is to eliminate contact between Sierra Nevada bighorn sheep and domestic sheep and goats. Domestic sheep and goats can carry pathogens that are linked to fatal pneumonia in bighorn sheep, and can quickly devastate a bighorn population.
Other actions to help sheep recover include translocating Sierra Nevada bighorn sheep from large wild herds to supplement depleted herds and reestablish extirpated herds. Captive breeding would only be used if recovery goals for wild herds cannot be reached through translocation of bighorn sheep. This method would help maintain the genetic diversity of this subspecies, increase population size, and reduce the level of population fragmentation.
“Years of hard work and planning have resulted in a plan that we believewill recover this magnificent keystone species of the high Sierra,” said Thompson.
The Sierra Nevada bighorn sheep population was thought to be part of a larger California bighorn sheep subspecies, but genetic and morphological research now indicates that Sierra Nevada bighorn sheep should be classified as a separate subspecies. The Sierra Nevada bighorn sheep is also listed by the state as endangered.
Recovery plans are blueprints for action by federal and state agencies, other organizations, and citizens, and do not obligate the expenditure of funds or require that actions be implemented.
The goal of recovery plans is to recover species to a level where protection under the act is no longer necessary.
The California State Department of Fish and Game (DFG) is the lead agency in this multi-agency effort to recover Sierra Nevada bighorn sheep. Immediately following listing, DFG established a recovery program based on the allocation of funds by the California legislature specifically for that purpose. The recovery program has focused on monitoring population trend, identifying limiting factors, and implementing recovery actions. Recovery actions that are currently being implemented include translocations to reestablish populations, use of prescribed fire to enhance habitat, grazing management to minimize disease risk, and predator management.
The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals and commitment to public service. For more information on our work and the people who make it happen, visit http://www.fws.gov.
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