Family Planning for America’s Wild Horses

Scientists propose a new way to rescue our out-of-control wild horse population.
America has a lot of wild horses to rescue, and there are a lot of ideas about how to do it. (Photo: John B. Mueller/Getty)
Aug 22, 2013· 2 MIN READ
Richard Conniff is the author of House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth and other books.

It might have made sense in the beginning: Forty years ago, responding to ardent public campaigning by horse enthusiasts, Congress ordered federal agencies to protect and manage wild horses as a native species. The horses were in fact domesticated. They had been introduced by early settlers and then gone feral.

But horses had once been native to the American West, until they went extinct roughly 12,000 years ago. So at least in theory, it was a restoration—minus the saber-tooth tigers and other Pleistocene predators that had kept the original horse population in check.

The Bureau of Land Management (BLM), which administers 264 million acres of federal land, got the job of figuring out how many horses the habitat could support. (Each horse requires five gallons of water and 18 pounds of forage daily.) Congress also assigned BLM the chore of rounding up and removing horses when they threatened to exceed that amount.

But from that arguably logical start, what has resulted looks a lot like wildlife management as practiced by circus clowns, with Congress sending down a welter of confusing and even self-contradictory mandates. There are now an estimated 33,000 free-roaming horses in the American West, mainly in the Great Basin country of Nevada, Oregon, Utah, and Wyoming. That’s 10,000 more than the number the BLM figured, and the population could grow to 100,000 over the next six or eight years, meaning widespread habitat degradation and, the prospect, in an era of increasing droughts in the American West, that tens of thousands of horses will die of starvation or thirst.

It doesn’t necessarily meant that BLM has fallen down on the job, according to Robert A. Garrott, a Montana State University ecologist and the lead author of a paper about the wild horse problem published today in Science. The agency has routinely removed 6,000 to 9,000 horses per year from public lands. But only about 2,000 of them get adopted, and, responding once again to public campaigning, Congress has refused to allow the excess horses to be euthanized or slaughtered for meat.

That means the federal government currently pays to maintain 42,835 horses in holding facilities at a cost of $46 million annually—and rising far too fast to be sustainable. Because of pressure on the federal budget, Congress has also recently refused to allocate further funds for the removal and maintenance of excess horses. That’s a mandate for even more horses on the land. But when a drought occurs, as is happening this summer, Congress also bows to public pressure by paying to haul water out to horses in the wild.

Isn’t there a better way? Horse advocates argue that if the federal government simply left horse populations alone in the wild, they would self-regulate. “But they have such a passion for horses that they’re blind to the biological facts,” says Garrott. “If they self-regulate, they die of starvation and lack of water.”

The article in Science proposes instead that the federal government should begin a campaign to limit horse numbers with contraceptives. The Environmental Protection Agency has recently authorized use of two contraceptive vaccines for mares, including one that’s effective for up to three years. Chemical sterilization of males by injection is also available, but because it’s permanent, it’s also more controversial.

The contraceptives generally need to be administered by hand, rather than by dart, says Garrott, meaning that such a program would continue to require rounding up horses for treatment. Moreover, it would merely cut the rate of population growth in half, not stop it completely. But that’s enough to make a major difference. It means BLM would need to remove only 2,000 to 3,000 horses annually to maintain its target population. And every horse that didn’t have to be removed because of the contraceptive program would save taxpayers more than $16,000 in maintenance costs over its lifetime.

It isn’t a perfect solution, says Garrott. But it’s infinitely better than continuing to do business as usual. To see where that will inevitably lead, he says, look at Australia, where a massive drought is currently devastating the population of 400,000 wild horses. To reduce the suffering, authorities there recently approved a program to shoot 10,000 horses from helicopters.