Federal land managers have removed all 122 mustangs from rugged western Colorado rangeland known as the West Douglas herd area, inflaming tensions with wild horse advocates who called the helicopter roundup inhumane and unnecessary.

No more mustangs remain on the 128,000 acres of sagebrush, ravines and canyons after the eight-day roundup, according to the U.S. Bureau of Land Management’s aerial surveillance. Four horses were euthanized after they were captured, including one that had a broken leg. The BLM said all four of the horses, including the one with the broken leg, were put down because of chronic or preexisting issues.

The land, which had about 20 wild horses in the 1970s, is unsuitable for mustangs, in part because in drought years there is little water for the animals to drink, and because horses have moved onto private land, said Steve Hall, communications director for the BLM in Colorado.

“It’s really rough country,” he said of the land bordering Utah. “There is not a lot of forage out there. There is not a lot of water. It’s never been the right place to manage horses.”

The horses, after being driven into makeshift corrals by a low-flying helicopter, are all en route or already in holding pens in Cañon City. This time, they were vaccinated upon arrival – which is “new standard operating procedure” after the deaths of 145 horses at the holding facility last year due to equine flu, Hall said.

The last roundup of West Douglas horses, in 2021, resulted in the removal of nearly 450 animals, of which about one-third died seven months later in an equine flu outbreak at the Cañon City holding pens. The animals were not vaccinated against the flu after their capture, in violation of federal policy.

The horses were removed in 2021 in an emergency roundup following a wildfire, which investigators speculated had damaged the horses’ lungs and made them more susceptible to flu, a normally survivable illness. Academic studies about what contributed to the horses’ deaths are not yet complete.

“We are still not clear on what it was that impacted those horses so badly,” Hall said Monday.

After a few weeks or months in the holding pens on the grounds of a state prison in Cañon City, the horses will either go to long-term pasture or up for adoption. Typically, the West Douglas herd is not as popular at adoption events because the horses are almost all bays – brown with black mane and tail – and are smaller than domestic horses, Hall said.

As is typical in federal roundups, wild horse advocates traveled to the remote area to witness the helicopter drive the animals into corrals. And as often happens, those advocates said the area where they were permitted to stand provided no clear view of the horses, which were blocked by high ridges in the terrain, as well as trucks and equipment, as the animals were pushed into corrals.

Hall said several of the trap sites, which move frequently to get closer to the areas frequented by bands of horses, were on private property. “Landowners just do not want the folks who show up for horse gathers on their property,” he said. “There’s not a lot of trust between the horse advocate community and ranchers in western Colorado.

“We do everything we can to manage the public’s wild horses in a humane and safe fashion. There are a lot of emotions on both sides of the issue.”

The public land where the horses have roamed for decades is also leased by oil and gas companies, and ranchers who graze cattle and sheep.

Scott Wilson, a wildlife photographer and a spokesman for the American Wild Horse Campaign, watched the roundup for five days and called it a “blunt force approach” to managing mustangs.

“There is really no wild horse emergency,” he said, noting that horses die off naturally during Colorado’s harsh winters. Only about 3% of the 128,000 acres in West Douglas is private land, leaving more than 1,000 acres for each horse, Wilson estimated.

The horses were healthy, there were ponds for drinking and plenty of grasses, Wilson said. “There is no ecological or health emergency,” he said. “It’s simply about zeroing out a herd that the BLM does not want to manage.”

The American Wild Horse Campaign, a national nonprofit pushing to ban helicopter roundups, said the method of removal is inhumane and also expensive. Wilson said he counted 17 contractors and federal regulators at the trap site on a day they managed to gather just five horses.

The BLM paid $187,000 to the helicopter pilot and crew for the roundup, which does not include the cost of holding and feeding the horses for the rest of their lives. About half of mustangs are adopted, Wilson said. “The notion that removed horses get adopted is only half true,” he said.

Across the highway from West Douglas, in what’s called the Piceance-East Douglas herd management area, the federal government has enlisted volunteers to shoot birth control darts into wild mares.

Last summer, the federal agency used a helicopter to remove 761 horses from the Piceance. The rangeland still has about 750 horses, and it’s likely to see another roundup in the near future because federal land managers say the appropriate number for the 200,000 acres is 235 wild horses.

Wilson questioned why the BLM has determined that West Douglas’s appropriate herd number is zero when the terrain is the same as in the Piceance-East Douglas, just across Colorado 139. He said he travels from Denver to photograph mustang roundups so the public will know what happens; mustang advocates have asked the BLM to film the roundups with cameras on the helicopter.

“I’m only showing up because observation would be otherwise nonexistent,” Wilson said.

The roundup that ended Saturday was the first in Colorado this year. The BLM plans to remove 20 horses from the Sand Wash Basin, in far northwestern Colorado along the border of Wyoming, at the end of September.

The BLM removed more than 30,000 horses in 2021 and 2022 from rangeland across the West, including about 1,500 in Colorado. This year, the agency plans to remove about 6,000 horses nationwide.

Tracy Scott, who runs Steadfast Steeds, a mustang sanctuary and education center, said there are more wild horses in sanctuaries and holding pens at this point than in the wild in Colorado.

Scott was just appointed to the state’s new task force that will determine how Colorado can have more authority over wild horse management, a key issue for Gov. Jared Polis and his husband, Marlon Reis, an animal rights advocate.

At her sanctuary, southwest of Grand Junction in Glade Park, Scott has 23 horses and one burro. Part of her work is to educate taxpayers about the cost of roundups and boarding mustangs. The average lifetime cost is estimated at $48,000 per horse, she said.

“More than just horse people need to be aware of what is happening with our wild horses,” she said.