Surfeit Of Bighorn Sheep Surveyors

The California Department of Fish and Wildlife, U.S. Forest Service, and Society for the Conservation of Bighorn Sheep are now turning away voluntary census takers for the 2017 San Gabriel Mountains bighorn sheep survey.
The annual event, which has been held in late February and early March for over 30 years, has allowed biologists to track Southern California’s unique population of bighorn sheep for over 30 years. This year’s survey is scheduled to take place on February 26 across the expanse of the San Gabriel Mountains within Los Angeles and San Bernardino counties. Late last month, Fish and Wildlife, the Forest Service and the bighorn sheep protective group were seeking volunteers but the Society of the Conservation of Bighorn Sheep has now mounted on its website that “Sign-ups are now closed for this year’s survey! We’re sorry, but due to an overwhelming response of more than 200 people registering between February 1st and 5 p.m. February 2nd, we’re at capacity. Thank you for your interest!”
The California Department of Fish and Game organizes an event to count the population of bighorn sheep (Ovis candadensis nelsonii) in the San Gabriel Mountain Range. This survey is held with the support of the National Forest Service. A major portion of the survey takes place within San Bernardino County, as the sheep tend to gravitate toward the eastern end of the San Gabriels. The survey assists in assessing the overall health of the herd. This herd has been used in the past as a source population for translocation efforts to re-populate herds in the Mojave Desert that have been extirpated. Due to the low carrying capacity of the desert habitat and the attendant small herd groups, it is a natural occurrence that some bands of bighorn sheep will die, leaving the range vacant. It is also natural that the ranges with larger populations of bighorn would naturally re-colonize the vacant ranges. Biologists call a group of spatially separated populations of the same species which interact at some level a metapopulation.
Through the development and occupation of the desert by humans, much of the natural repopulation efforts are not successful because man-made structures like highways, renewable energy developments and aqueducts have restricted bighorn movement. Translocations are thus necessary to properly manage and conserve the bighorn sheep.
In 2013 biologists surveying the Mojave Desert’s mountains noted a significant decline in the bighorn sheep population in a substantial portion of the desert region. Utilizing helicopters to scour over 75,000 acres on and around Old Dad Mountain, the Marble Mountains, and the Kelso, Bristol, Clipper, Soda, Providence, Granite, Hackberry and Woods ranges during a two week period in late October and November of that year, scouts were able to spot fewer than half the number of bighorn they typically see during similar flyovers. Between May and August 2013 a pneumonia outbreak among what was considered one of the hardiest of the state’s herds killed as many as 45 bighorn sheep in the Mojave Desert.
Pneumonia can incubate in the animals for months with little or no outward indication for weeks and then strike the animals dead in a short time after the disease manifests. Sick animals are highly contagious and wildlife officials at that time were concerned that there might be a catastrophic die-off of the bighorn, which did not occur.
The San Gabriel Survey utilizes a simultaneous ground and aerial count. Several bighorn sheep in the region have been marked and collared in the past. With re-sighting of the marked sheep and the overlapping aerial and ground crews, a reliable estimate of the population can be derived through statistical methods based on the actual observations. The ground crews are manned by volunteers from the general public.
There are nine trails that volunteer groups cover on the ground, those being Lookout Mountain, Cattle Canyon, Day and Deer Canyons, Barrett-Cascade Canyon, South Fork of Lytle Creek, Middle Fork of Lytle Creek, Highway 39, Mt Baldy and the South Fork of Big Rock Creek.

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