Sierra Nevada Bighorn Sheep- Miles Loef

Sierra Nevada Bighorn Sheep

By: Miles Loef

Description and Ecology

The Sierra Nevada Bighorn Sheep, also known also as the Ovis canadensis sierrae,

is found in the Eastern region of the Sierra Nevada Mountain range located in California. The size of the animal varies between males (rams) and females (ewes), in which males weigh on average between 120-220 pounds and females between 100-150 pounds. Both males and females have permanent horns, but male’s horns are much larger and more curved than females. They have many similarities to other sheep that are typically associated with desert environments, but specifically they vary in fur color. Their fur ranges from dark brown to white with its legs and eyes having white hair only. The Sierra Nevada Bighorn Sheep’s survival in its environment requires them to be agile on rocky slopes, so they rely on sharp eyesight to avoid/detect predators and a stocky build with strong legs. They on average 2.5 to 3.25 feet tall.

Male (Ram) Sierra Nevada Bighorn Sheep

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Geographic and Population Changes

In 1995, the Sierra Nevada Bighorn Sheep had a population size of about 100 that was seen across 5 separate areas in the Sierra Nevada Mountain Range. There is currently about 16 herds spanning from the Olancha Peak in the south to the Sonora Pass in the north. In 1999, the population had only grown to about 125 individuals. But with favorable conditions for population growth, it was estimated in 2007 that there was between 325-350 total Sierra Nevada Bighorn Sheep, at the time of the recovery plan. Populations are still rising and have exceeded the 325-350 found in 2007 and the total current population is unknown.

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Bighorn Sheep Range Along the Eastern Sierra Nevadas

Type of Listing: Endangered

The Sierra Nevada Bighorn Sheep was listed as endangered on January 3, 2000 because of factors like predation and accidents. One of the main factors is when predators take out young animals when large rates of potential reproduction can still occur. The primary predator of Sierra Nevada Bighorn Sheep is the mountain lion that claimed 96% of all deaths from about 1995-2000. Unfortunately, freak accidents like avalanches and highway collisions also accounted for the second largest amount of deaths of this animal in that period, further putting them at risk of extinction.

Main Threats

The main threats that the Sierra Nevada Bighorn Sheep still faces today is disease, predation, and decreased genetic variation. The main disease that threatens their existence is contact with domestic sheep in which pneumonia and other respiratory infections are easily transferred with deadly effects. Many times, even small amounts of contact between domestic sheep and these animals can cause sickness and death. For predation, mountain lions continue to pose the biggest threat where they have been making the most damage in the Sierra Nevada Bighorn Sheep winter range. Since the population is low, there is a long-term threat to the species genetic variation and conservation.

Recovery Plan

This recovery plan was published on February 13, 2008. There are 8 main parts to the recovery plan for the Sierra Nevada Bighorn Sheep.

1.     Protect bighorn sheep habitat

2.     Decrease the chances of bighorn sheep contracting diseases causing mortality and morbidity.

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3.     Increase the total number of herds, and therefore increase the population of bighorn sheep

4.     Introduce a genetic management plan to sustain genetic diversity of Sierra Nevada bighorn sheep

5.     Oversee status and tendencies of bighorn sheep herds, their habitat, and threats to them.

6.     Begin or continue needed research

7.     Stress public outreach and sharing of information.

8.     Establish an advisory team for communication and coordination

The expected cost of this recovery project is estimated to be $21,730,000 million dollars over the course of twenty years. With steady population growth, there is expected to be a downlisting in this year 2017 and a full delisting in 2027.

What Can You Do?

1. Restrict Contact of domestic sheep and Sierra Nevada Bighorn Sheep
1. Make sure ranchers are doing their best to make sure that their fencing is secured and stable to prevent interaction

1. Be part of an information campaign of why these animals are such a benefit
2. Participate in a survey to increase your knowledge and others about the species

Other Resources

Here are some other links to resources so you can learn more and get involved in protecting the Sierra Nevada Bighorn Sheep!

1. http://sierrabighorn.org

                    Sierra Nevada Bighorn Sheep Foundation

1. http://www.dfg.ca.gov/snbs/SheepFacts.html

                    California Department of Fish and Wildlife

1. http://www.biologicaldiversity.org/species/mammals/Sierra_Nevada_bighorn_sheep/index.html

Center for Biological Diversity

Bibliography

California Department of Fish and Wildlife. “Recovery Program.” Sierra Nevada Bighorn Sheep

Facts - California Department of Fish and Wildlife, www.dfg.ca.gov/snbs/SheepFacts.html.

Cassel, Bonnie. “Sierra Nevada Bighorn Sheep Description and Biology.” National Parks Service,

U.S. Department of the Interior, www.nps.gov/yose/learn/nature/sheep-biology.htm.

Service, U.S. Fish and Wildlife. Species Profile for Sierra Nevada Bighorn Sheep (Ovis Canadensis

Ssp. Sierrae), ecos.fws.gov/ecp0/profile/speciesProfile?sId=3646#rangeInfo.