Bureau of Land Management issues Record of Decision on wild horse fertility control study


Bureau of Land Management

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Nevada State Office

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RENO, Nev. – On March 6, 2020, the Bureau of Land Management (BLM), Nevada State Office issued a Decision Record (DR) and Finding of No Significant Impact (FONSI) based on analysis provided in the Oocyte Growth Factor Vaccine Study Environmental Assessment (EA). The BLM developed the study in response to seeking a reliable, longer lasting fertility control method to maintain healthy, sustainable wild horse herds. The EA and DR/FONSI are available online at https://go.usa.gov/xpEvc.

Two government agencies are working together to reduce the overpopulation of wild horses on America’s public lands, by researching a single-dose contraceptive vaccine on previously removed excess wild horses. On December 5, 2019, the BLM, Nevada State Office in cooperation with U.S. Department of Agriculture, Animal and Plant Health Inspection Service’s National Wildlife Research Center announced the availability of a draft Environmental Assessment (EA) regarding the population growth suppression study that would test the contraceptive effects of an oocyte growth factor vaccine for use with wild horses.

The purpose of the decision is to determine whether the one-dose oocyte growth factor vaccine could be a reliable, long-lasting fertility control method for future BLM wild horse herd management actions that aim to achieve and maintain a thriving natural ecological balance. The purpose of the action is to test, in wild horses, the efficacy of a vaccine against two oocyte growth factors, where the vaccine has been formulated to cause long-lasting contraception from a single dose.

There are currently more than 88,000 wild horses and burros on the landscape – a level more than three times the appropriate management level that BLM has established for the healthy management of public lands and for the health of the herd. This population continues to expand by 15-20 percent every year. These populations are overgrazing and destroying native ecosystems that have evolved over thousands of years, threatening hundreds of native wildlife species and people and communities across the West dependent on public lands for their livelihoods. For this reason, the BLM is exploring contraceptive methods and strategies for wild horse and burro populations.

The BLM continues to invest in a diverse portfolio of research projects to develop new, modern technologies and methods for wild horse and burro management. The research is aimed at finding safe and effective ways to slow the population growth rate and reduce the need to remove animals from public lands. The studies are in response to a 2013 recommendation from the National Academy of Science to develop new or improve existing population growth suppression methods for wild horses and is in accordance with The Wild Free-Roaming Horses and Burros Act of 1971.



The BLM manages more than 245 million acres of public land located primarily in 12 western states, including Alaska, on behalf of the American people. The BLM also administers 700 million acres of sub-surface mineral estate throughout the nation. Our mission is to sustain the health, diversity, and productivity of America’s public lands for the use and enjoyment of present and future generations.