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Sierra Nevada Bighorn
407 West Line St.
Bishop CA 93514
Sierra Nevada Bighorn Sheep Recovery Program
Video describing March 2013 reintroduction effort (click to open full size Youtube window)
Animated map showing Olancha animal movements from release site (2 months movements)
Helicopter ferrying in Sierra bighorn (photo courtesy Lucas Barth)
Sierra bighorn at processing site during translocation (photo courtesy Lucas Barth)
Released ewe heads off towards Olancha Peak (photo courtesy Lucas Barth)
Olancha Peak - in progress
March 25, 2013 marked the first translocation to create a new Sierra Nevada bighorn sheep herd since 1986 when the Mono Basin herds at Mt. Warren and Mt. Gibbs were first repopulated. Ten pregnant ewes and four rams were released on March 25-26. Each is fitted with a satellite GPS collar allowing daily monitoring of their movements and health for the first 30 months. Additional bighorn releases are planned for this population within two years to augment the original herd. During the first few months of observation, all animals seem to be adapting to their new home. Lambing season, May-July, has resulted in eight lambs seen so far. One ewe apparently lost her lamb shortly after birth and one ewe has not yet been observed. In May, one ram returned home about 25 miles north to the Mt. Langley herd unit, leaving three rams remaining.
Big Arroyo and Laurel Creek - within 5 years
Depending on the availability of source stock from existing herd units, we will begin repopulating this historic habitat in two to five years. This recovery unit, located in the Great Western Divide has not been occupied since early in the twentieth century. Since this area is geographically isolated from the main body of the Sierra Nevada, this herd will be an important reservoir of bighorn separate from the east side populations. Creating a herd in the Great Western Divide area has some additional logistical challenges not common to most other herd units. Monitoring of these populations will require significant effort in the form of than 25 miles of backcountry travel to get there.
Taboose Creek - pending colonization
This herd unit, adjacent to Sawmill Canyon and just south of Coyote Flat, is showing signs of incipient colonization. Our field crews have repeatedly observed rams within the herd unit boundaries. Hikers and climbers have provided photographs and sightings of ewes as well, but it is unclear whether a breeding population exists yet. Depending on how the potential colonization proceeds, bighorn may or may not need to be reintroduced through human assistance. As the other reintroductions proceed, we will continue to monitor and explore this herd will continue to be monitored and explored to determine the best course of action.
This herd was augmented with six preganant ewes moved to Lundy Canyon in 2009. Three ewes were moved from Wheeler Ridge and three ewes came from Mt. Langley. All six of the ewes survived at least two years and produced lambs. During the next three years, three perished. One died of unknown causes during a harsh winter, one fell down a small cliff and one was killed by a mountain lion. Two rams were moved to Mt. Warren in 2003. The following year one was hit by a car on Conway Summit and perished. The other survived for nine more years likely producing offspring with different genetic stock. This herd will be augmented again in the next one to two years to expand their geographic range south to include Mt. Scowden and Mt. Warren, while diversifying the base genetic stock.
This herd was augmented with three ewes, two of which were pregnant, from the Mt. Langley herd in 2013. Genetic analysis indicates low genetic diversity in this herd. The newly-arrived ewes were selected for high genetic diversity to help increase the genetic diversity of the herd in an attempt to raise the low reproductive rates observed in past. We expect to add additional ewes into this population in the next one to two years to continue this effort at managing genetic diversity while expanding the population size.
This herd was augmented with three pregnant ewes from the Mt. Langley herd in 2013. This very small population should benefit by increasing the number of ewes to complement and assist the natural colonization of this herd. The translocated ewes were selected for high genetic diversity to help ensure that the genetic stock remains diverse. Having collared animals in this newly colonized area will also help to define habitat usage patterns and assist in comprehensive population surveys.
Five pregnant ewes were moved to Mt. Baxter from the Wheeler herd in 2005. Later that year three of the translocated ewes moved north to Sawmill Canyon. One of the remaining ewes moved south to Mt. Williamson in 2007. All five ewes survived to lamb for at least two years. Four of the relocated ewes were killed by mountain lions between 2007 and 2009. The remaining ewe survived and reproduced at Mt. Baxter for many years. This herd is currently large enough to be a source for translocation stock rather than requiring additional augmentation.
Mt. Langley was augmented with a single ram from the Wheeler Ridge herd in 2001. He was released further north, in the Mt. Williamson area, but moved south over a period of several months and became a permanent resident of the Mt. Langley herd for at least six years. This herd is currently large enough to be a source for translocation stock rather than requiring additional augmentation.
“Many endangered species remain on the brink of extinction with poor prospects for recovery after they receive federal protection. Through our conservation efforts, we have a unique opportunity to reach recovery goals for an alpine specialist that is native only to California.”
------------------ Program Manager Tom Stephenson ------------------