06/15/2026
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In 2023, researchers at the University of Wyoming took four wild b***os straight off federal rangeland in California, placed them among sheep, and tested whether an animal the government had been struggling to give away could work as a coyote deterrent.
Two of the four bonded with the flock within weeks and stood guard with eleven times the vigilance rate of the sheep around them. One had to have her entire pasture redesigned before she would stay.
The study was the first controlled test of wild BLM b***os as livestock guardians, and the animals that arrived unbroken and unadoptable turned out to already know the job.
We covered guard llamas on this page. The principle is actually identical. A solitary animal from a non-prey species is placed among sheep, adopts them as its herd, and attacks anything canid-shaped that approaches. Llamas do it through an innate hatred of canids inherited from South American wild dogs. B***os do it through territorial aggression and a body that can stomp, kick, bite, and chase a coyote until it leaves or dies.
A mature b***o weighs 400 to 500 pounds, runs faster than a coyote in a straight line, and has a kick that can shatter bone. Ranchers across the West have used domestic donkeys as flock guards for decades. Nobody had tested whether a wild b***o straight off the range could do the same job without domestication.
The study was led by John Derek Scasta at the University of Wyoming's Laramie Research and Extension Center and published in the Sheep & Goat Research Journal in 2024. The four b***os were jennies, all female, removed from BLM land in California under the federal wild horse and b***o management program. They arrived at the research station with no exposure to sheep, no training, and no social bond to anything except each other and whatever herd structure they had maintained on the range.
Integration took roughly five weeks overall, but the individual differences were enormous. B***o 7092 figured it out fast. Within days she was positioning herself in or near the sheep flock during more than ninety percent of observations. She grazed where the sheep grazed. She moved when they moved. She watched the perimeter while the sheep fed with their heads down. Her vigilance rate averaged 25.7 percent of observed activity. The sheep she was guarding averaged 2.2 percent. One animal in the flock was scanning the horizon more than eleven times as often as everything else in it.
B***o 7107 was the opposite. Placed in a large 640-acre pasture with complex terrain, she drifted. She walked toward roads, toward cattle in adjacent fields, toward horses, toward water points at the edge of the property. She showed no interest in the sheep. Researchers pulled her out and moved her to an 18-acre meadow with thirty ewes and one ram. A smaller space, a simpler landscape, fewer distractions. She bonded within five days. The pasture size had been the problem, not the b***o.
During the study, a neighbor reported seeing a coyote inside a pasture that contained a donkey-guarded flock. No sheep were killed. In flocks without integrated donkeys, two sheep were lost to depredation. The researchers were careful not to overstate the sample. They wrote that future work was still needed to prove direct predator reduction in working ranch systems. But the pattern was there.
The BLM removes thousands of wild b***os from western rangeland every year. The animals go to adoption events, holding facilities, and in some cases to long-term pastures in the Midwest where they live out their lives at taxpayer expense. The program is expensive, controversial, and ongoing because the b***o population on public land exceeds what the range can carry. Most adopted b***os end up as pasture pets. Some end up in slaughter pipelines that the BLM has struggled for decades to close.
Four of them ended up in Wyoming guarding sheep. They arrived wild, numbered, and unbroken. Within five weeks, the ones that worked were standing watch over animals they had never seen before, scanning for predators they had always known how to handle, doing a job nobody had asked them to do until a researcher looked at a holding pen full of unadoptable federal b***os and thought: these animals already know how to survive coyotes. They have been doing it their entire lives on the range. The only thing that changed was what they were protecting.
Source: Scasta et al. (2024), "From Wild to Watchful: Integrating BLM Donkeys (B***os) for Sheep Ranch Protection," Sheep & Goat Research Journal. USDA APHIS livestock protection guidelines. BLM Wild Horse and B***o Program.
