CHEYENNE, Wyo. — The federal government is preparing to launch a new round of studies into ways to prevent wild horses and burros from overpopulating Western rangelands, including making contraceptive drugs last longer.
Right now, the longest-lasting contraceptives the U.S. Bureau of Land Management uses on female wild horses, a drug called PZP, lasts no more than a year or two. The BLM darts mares with the drug in liquid form or injects it in pellet form in mares that have been rounded up.
One new study will attempt to develop a permanent contraceptive. Another will try to devise a new way to deliver PZP to make it last longer.
“It’s all about creating that broad suite of tools, because not every herd is the same,” BLM spokesman Jason Lutterman said Friday.
The BLM plans 21 research projects that will cost $11 million over five years. Several will involve universities and the U.S. Geological Survey, and four involving the survey already are underway.
Other upcoming research projects will include seeking an incision-free, minimally invasive method of surgical sterilization for mares and testing the efficacy of contraceptives on female burros.
The West is home to some 58,000 wild horses and burros. The animals’ numbers have grown by about 18 percent in just the past year, according to the BLM.
Yet fewer people these days are adopting rounded-up wild horses: About 2,500 a year, down from around 8,000 a year in the early 2000s. Thousands of un-adopted horses are sent to off-range pastures and corrals, where the cost of keeping each for the remainder of its life averages nearly $50,000.
Wild horses are a contentious topic in the West, where ranchers say they damage the rangeland and eat forage that otherwise would be available for cattle. Horse advocates say the BLM’s roundups are cruel and the government falls short in ensuring the herds’ long-term viability.
Both sides have sued the BLM over wild horses with varying success. In April, a federal judge in Cheyenne dismissed a lawsuit filed by Wyoming that sought to force the BLM to immediately round up overpopulated herds.
Last week, the U.S. Fish and Wildlife Service denied a petition filed by Friends of Animals and The Cloud Foundation seeking Endangered Species Act protection for wild horses. Fish and Wildlife found that wild horses aren’t significantly different from domestic horses.
Wild horse advocates disagree on the use of contraceptives.
One group, the American Wild Horse Preservation Campaign, recently supported contraceptives as preferable to roundups for a Utah herd. The group opposes the new research, however, saying it will subject wild horses to “highly invasive” surgery.
Development of a permanent contraceptive drug for mares shouldn’t be considered because it would diminish wild horses’ genetic diversity, the group said in a release.