Wyoming’s mustangs suffered mass die-offs this winter, and there are probably about only half as many left as the Bureau of Land Management estimates, wild horse advocates tell Cowboy State Daily.
A BLM spokesman said the agency is double-checking its mustang population estimates.
Death On The Range
“I spent the first half of May documenting death and counting live horses,” Angelique Rea of Thermopolis, who has monitored and photographed mustangs for years, told Cowboy State Daily.
Chad and Lynn Hanson of Casper, founders of the Wyoming Mustang Institute, said they made a grim discovery when they checked on mustang herds this spring.
“We found the dead horses in Stewart Creek along (U.S. Highway) 287 south of Bairoil, and along Mineral X and Crooks Gap Road,” Chad Hanson told Cowboy State Daily.
How Did They Do This Winter?
The BLM estimates there are 8,181 mustangs in Wyoming, Kris Kirby, associate state director of the BLM’s Wyoming headquarters, recently told members of the Wyoming Legislature’s Joint Select Federal Natural Resource Management Committee.
She said the mustangs might have fared better than other wildlife this past winter, but the evidence of that was only “anecdotal” as of this spring.
That’s more than double the BLM’s target population of 3,725 mustangs in Wyoming.
It could be a while before the BLM has a clear picture of mustang winterkill, agency spokesman James Fisher told Cowboy State Daily on Friday.
“Unfortunately, we just won’t know for sure until the surveys/counts are accomplished,” he said.
Wild horse advocate Angelique Rea said winter took a devastating tool on some mustang herds in central Wyoming. (Photo Courtesy Angelique Ray) 
Wild horse advocate Angelique Rea said winter took a devastating tool on some mustang herds in central Wyoming. (Photo Courtesy Angelique Ray)
‘Mathematically Impossible’
Meanwhile, Chad Hanson said he thinks 8,000-plus is an “implausible” number for the Wyoming’s mustang population.
Estimates put the population at roughly 4,700 mustangs in 2022, he said. And since the horse’s population can increase by about 15% to 20% annually, it’s “mathematically impossible” for the population to have shot up to more than 8,000 is a single year.
Fisher said the BLM had received an email from Hanson, and that Hanson raises some valid questions.
“I’m glad he asked that” about the mustang population estimations, and the BLM is looking into it further, Fisher said.
Rea said that if she had to venture a guess, “I would not go with more than 4,000 horses” still alive after this past winter.
Mustang population estimates might be thrown off by including horses on the Wind River Reservation, which should be considered a separate population, or domestic horses that had recently been abandoned by their owners, she added.
Some Places Worse Than Others
Mustangs pulled through the winter fairly well in some areas, which might leave the mistaken perception that they’re fine all across their range, Rae said.
For example, around Green Mountain near Jeffrey City, it seems that most horses survived, she said. Those mustangs appeared to be doing well last month, even though there were fewer spring foals than usual.
But in other areas across central Wyoming — such as Crooks Peak, Stewart Creek and Lost Creek — winter decimated herds, she said.
“In the Crooks Peak area, I haven’t found any live horses,” Rae said, adding that, “In the Antelope Hills, I would estimate 10%-15% losses.”
That’s significant for that particular herd, because “those horses are exceptionally tough and used to harsh winters,” Rae said.
The snow came early and stayed late on the mustangs’ range, she added.
“I couldn’t get out there until May 1. There are probably a lot of bodies out there that we’re never to going to find,” she said.
Sad Vigil On Stewart Creek
Rae said she has some friends who live on the edge of the Stewart Creek HMA, and they watched that herd suffer terribly over the winter.
In March, many of the horses looked emaciated, she said
“By the end of March, the snow started to melt” and it looked like the Mustangs might have a chance, she said.
“Then we had three big snowstorms hit in April, and my friends watched 50% of the bands of mustangs disappear,” Rae said. “It was just too much. They had nowhere to go, no food.”
Mark Heinz can be reached at mark@cowboystatedaily.com.
