By Mead Gruver
The Associated Press
CHEYENNE — 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, 30 to 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 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 Office spokeswoman Kristen Lenhardt said by e-mail Tuesday.