Courtesy Larisa Bogardus. BLM
Courtesy Larisa Bogardus. BLM
An animal rights group has filed a lawsuit seeking to stop the federal government from administering birth control to wild horses in the West.
Friends of Animals, a nonprofit, claims the U.S. Environmental Protection Agency approved the birth control agent — porcine zona pellucida or PZP — without properly researching its impact on wild horses.
In its complaint, the group has asked a federal judge to order EPA to suspend registration of PZP until it conducts a special review of the substance, which would effectively halt birth control treatments for wild horses.
Western rangelands are inhabited by roughly 60,000 wild horses, which are protected by federal law and managed by the U.S. Bureau of Land Management in cases of overpopulation.
The BLM occasionally rounds up wild horses, removing some from the rangeland while treating mares with PZP.
According to Friends of Animals, the EPA waived requirements that PZP be analyzed for toxicity, ecological effects and environmental fate when the substance was registered in 2012.
Since then, new information has come to light showing that treating mares repeatedly with PZP can impair their ovarian function and potentially cause infertility, the plaintiff claims.
Even after its effects have worn off, PZP disrupts a mare’s reproductive cycle, making it more likely she will give birth during a seasonally inopportune time, the lawsuit said.
Foals born in wintertime are more likely to die from low temperatures and lack of food than those born during the spring and summer.
Friends of Animals petitioned the EPA to consider these and other impacts as part of a special review of PZP, but the agency decided it wasn’t warranted and referred the matter to BLM.
The plaintiff argues this decision was made “arbitrarily and capriciously” in violation of federal pesticide law.
Any action that would boost wild horse populations in the West — such as a suspension of birth control — is of concern to ranchers whose cattle compete for grazing resources.
“The problem with feral horses out on the range is they double in population every four years if left unchecked,” said Tom Sharp, a rancher near Burns, Ore., and chair of the Oregon Cattlemen’s Association’s endangered species committee.
Treating the horses with birth control is more humane than allowing their populations to become excessive, he said.
“We know the feral horses are suffering on the range,” Sharp said. “They don’t have enough food or water and a lot of them just die.”
When horses consume too much grass, it leads the BLM to reduce the number of cattle in the area, he said.
“As you have less food and forage available, something has to give,” Sharp said.
Horses are also more adept than livestock at jumping over fences that are intended to protect riparian areas from trampling, which can harm sensitive fish species, he said.
“The government is in desperate need to have some tool to manage the wild horse and burro program,” Sharp said.