The Bureau of Land Management announced today that it will be conducting 11 gathers of wild horses in Fiscal Year 2011 for the primary purpose of applying a fertility-control vaccine to mares. During these gathers, known as “catch, treat, and release,” the BLM will apply the fertility-control vaccine known as PZP to approximately 890 mares, which will be treated and then released back to the specific Herd Management Areas from which they were gathered.
“These ‘catch, treat, and release’ gathers are an innovative way of working to control the population growth of wild horse herds,” said BLM Director Bob Abbey. “If these fertility-control treatments prove successful, we can lengthen the time between some gathers, saving taxpayer dollars by holding down gather and holding costs.”
Porcine Zona Pellucida, or PZP, which makes mares temporarily infertile, is not available for commercial use. The BLM uses the PZP vaccine in cooperation with the Humane Society of the United States under Food and Drug Administration rules that apply to research on new animal drugs. This vaccine was first tested on the wild horses of Assateague Island (off the coasts of Maryland and Virginia), where a reduction in mare pregnancy rates was observed.
The “catch, treat, and release” gathers scheduled for Fiscal Year 2011 (covering October 2010 through September 2011), some already completed, are as follows: Hard Trigger Herd Management Area (HMA), Idaho; 40 mares for “catch, treat, and release (CTR); Black Mountain HMA, Idaho, 24 mares CTR; Pine Nuts Mountain HMA, Nevada, 45 mares CTR; Pilot Mountain HMA, Nevada, 76 mares CTR; Sulphur HMA, Utah, 70 mares CTR; New Pass-Ravenwood HMA, Nevada, 152 mares CTR; Bald Mountain HMA, Nevada, 45 mares CTR; Callaghan HMA, Nevada, 80 mares CTR; Rocky Hills HMA, Nevada, 50 mares CTR; Augusta Mountain HMA, Nevada, 77 mares CTR; and Clan Alpine HMA, Nevada, 232 mares CTR.
Under the Wild Free-Roaming Horses and Burros Act of 1971, the BLM protects, manages, and controls these animals to ensure healthy herd populations at levels consistent with the land’s capacity to support them. The BLM manages more than 38,000 wild horses and burros that roam public rangelands in 10 Western states.
Wild horses and burros have virtually no natural predators and their herd sizes can double about every four years. As a result, the BLM must remove thousands of animals from the range each year to control herd sizes. The estimated current free-roaming population exceeds by nearly 12,000 the number that the Bureau has determined can exist in balance with other public rangeland resources and uses. The appropriate management level is approximately 26,600.
Off the range, there are 37,800 other wild horses and burros that are fed and cared for at short-term corrals and long-term pastures. (As of October 2010, there were approximately 11,400 in corrals and 26,400 in Midwestern pastures.) All wild horses and burros in holding, like those roaming the public rangelands, are protected by the BLM under the 1971 law.