Winterkill Wiped Out Deer & Antelope Herds, But Wild Horse Population Is Exploding

There are more than twice as many mustangs in Wyoming as there should be, according to the Bureau of Land Management, and the past harsh winter that decimated some antelope and deer herds didn’t do much to reduce their numbers.

Mark Heinz

June 14, 20233 min read

Mustangs winter 6 14 23
(Getty Images)

Wyoming’s mustangs seem to have pulled though this past harsh winter well — maybe too well. There are more than twice as many on the range as the state is supposed to have, says a Bureau of Land Management official.

“We are not seeing the same level of mortality (among mustangs) that other ungulates are seeing,” according to preliminary estimates of the winter death toll, said Kris Kirby, the associate state director of the BLM’s Wyoming headquarters.

In parts of Wyoming, winterkill decimated mule deer and antelope herds.

Meanwhile, there are an estimated 8,181 mustangs roaming across roughly 5 million acres in 16 herd management areas that the BLM oversees in Wyoming, she said. The agency’s target population is 3,725 horses.  

And there’s no telling when, or how, the BLM will get the mustang population down to the target number, she said during her testimony to the Wyoming Legislature’s Joint Select Federal Natural Resource Management Committee.

Source Of Frustration

The mustangs are a huge source of frustration for some in Wyoming, members of the committee said.

“Are your hands tied? I realize you’re not the people in Washington making the decisions,” Sen. Sen John Kolb, R-Rock Springs, told Kirby and Brad Purdy, the BLM’s deputy state director of communications.

“I’d like to hear the truth, the truth of this,” he said, adding that the BLM horse management policy “isn’t working for us. This problem is getting bigger. This is the same problem we’ve had for years, for decades.”

Rep. John Winter, R-Thermopolis, said Wyoming’s objections to how mustangs are managed here seem to fall on deaf ears in Washington, D.C.

“What efforts are you, as agency people, doing to educate your superiors to the problem?” he asked.

Rounding up mustangs for adoption, and darting some of the mares with birth control drugs, hasn’t cut the number of horses quickly enough, he said, implying that lethal control might be needed.

“There’s another answer, but I think you both know that that answer is,” he told Kirby and Purdy.

Purdy noted that “euthanasia” of wild horses was allowed under the original federal 1971 Wild Horse and Burro Act. However, budget riders now attached to funding for mustang management don’t allow killing horses.

Mass Adoption

Kirby said the BLM is pushing for funding from U.S. Congress for a massive wild horse adoption program across the country.

The goal is to adopt out 20,000 mustangs each year across the United States for a period of several years until horse herds are reduced to target levels across Wyoming and other states, she said.

Live adoption sessions at the BLM’s mustang holding facility in Wheatland have resulted in only a handful of adoptions, Kirby said.

However, the “online corral” adoption program over the Internet has moved hundreds of horses from the facility so far this year, mostly to new homes in Eastern states.

“There is a big demand for these horses back East,” she said.

Cowboy State Daily last year told the story of Reno, Wyoming mustang that was adopted out and now serves as a police horse in New York City.

Mark Heinz can be reached at

Share this article



Mark Heinz

Outdoors Reporter