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CHEYENNE, Wyo. (AP) — The U.S. Bureau of Land Management and U.S. Geological Survey are proposing a study in southwest Wyoming to evaluate any side effects of spaying wild horses as one of the longer-lasting options for controlling herd sizes.
The BLM is taking public comments on a proposal to put tracking devices on male and female wild horses during a population-control roundup next summer or fall.
After a year, between 30 and 50 mares would be rounded up again, spayed and re-released for additional study. Goals include learning more about out how spaying might affect horse survival rates and behavior, such as whether they continue to roam with their group.
Comments on the roundup and research study in the Little Colorado and White Mountain herd management areas northwest of Rock Springs are due by Jan. 14.
Wild horses have a history of overpopulating public rangelands in Wyoming and elsewhere. Over the years, the BLM has abandoned a variety of population-control techniques including intrauterine devices, hormone implants and vasectomies as impractical or ineffective.
The most commonly used contraceptive drug now in use, PZP, remains effective only for a year or two. Routinely giving PZP to thousands of wild horses is difficult, according to the BLM.
"The BLM has and continues to examine all available birth control methods that can potentially reduce the rapid growth rate of wild horses on public lands," BLM Wyoming State Office spokeswoman Kristen Lenhardt said by email Tuesday.
The spayed horses would come from the 268 or so horses in the White Mountain herd management area. Horses in the Little Colorado area would be studied as a control group after the roundup reduces their population from around 330 to no more than 100 or so.
Horses rounded up and removed from the range would be offered to the public for adoption or sent to long-term holding pastures.
Overpopulated horse herds are a contentious topic in Wyoming. The horses compete with cattle for prime grazing areas, pitting ranching groups and the state against the federal government and wild horse advocates in a series of legal battles.
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