Newly published research out of the University of Wyoming suggests that sage grouse are suffering from free-roaming horses that have overrun the imperiled sagebrush-steppe habitat the birds depend upon.
Specifically, high densities of horses have a clear effect on the percentage of sage grouse nests successfully hatching, and on young birds surviving to see adulthood.
“Very clearly, our results suggest that if we don’t go over [horse population goals], then sage grouse nesting, brood-rearing and juvenile survival is going to perform much higher,” said Jeff Beck, a University of Wyoming ecologist who led research that was recently published in The Journal of Wildlife Management. “Where horses are sharing habitat with sage grouse, it’s really important to maintain horse numbers that don’t exceed the maximum [population goal].”
Beck’s research involved monitoring nearly 1,000 GPS-equipped sage grouse in southern and central Wyoming, from the Red Desert’s Adobe Town north to Conant Creek. The study team looked at how those birds fared in areas where there were no free-roaming horses at all. They also tracked nest success, as well as brood, juvenile and adult survival where horses dwell. As a barometer of equine density, the study used the Bureau of Land Management’s maximum “appropriate management level” — and how far the number of living, breathing horses departs from that seldom-achieved goal, despite regular roundups.
Results showed clear correlations suggesting that horses are harming sage grouse.
Nest survival decreased 4% for birds that lived among the at-objective herd population. It tumbled another 8% when horse numbers were three times the goal.
Sage grouse chicks were more affected: In areas where free-roaming horse numbers were triple the goal, survival rates were knocked down by 18% during each of two different stages of brood life.
Juvenile sage grouse were likewise impacted. Survival rates of youngsters older than 35 days were reduced by 8% where horses were present at or below population goals. The likelihood of making it to see another day tumbled by 18% when horse abundance reached three times the BLM’s goals.
Adult birds were the outlier. There was no evidence that increased abundance of horses influenced adult survival.
The findings about the harmful effects on younger age classes of grouse weren’t entirely a surprise.
A 2021 study out of Nevada published in the same journal found that for every 50% increase in horse abundance over the population goal, there was a corresponding 2.6% annual decline in sage grouse abundance.
Mechanisms of decline
“That [Nevada study] was just looking at population growth,” said Megan Milligan, a U.S. Geological Survey biologist who partnered with Beck on the recent Wyoming research. “There was no investigation in that research as to specific mechanisms of how free-roaming horses could be affecting grouse.”
The Wyoming research provides a clearer picture of how higher densities of horses are affecting sage grouse — by suppressing survival rates. Some 11% of the Equality State’s sage grouse habitat occurs within BLM herd management areas. And over 80% of the areas have populations exceeding the goal.
Horses can affect sage grouse directly, like, for example, by trampling nests, Beck said. But that’s unlikely to influence the population, he said. It’s more plausible that horses are causing indirect population-level effects by modifying sage grouse habitat.
“They break up sagebrush, they increase bare ground, they have a lot of impact on riparian areas,” Beck said.
With less cover, sage grouse in turn become more vulnerable to predation.
The indirect effects are most acute in the summer, when horses and sage grouse both tend to concentrate near water sources.
What about cattle?
Domestic livestock, too, tend to gather around water sources. But Beck is skeptical that cattle and sheep grazing is influencing sage grouse habitat the way free-roaming horses have within his study area.
“If there’s a problem with livestock, they take them off the range,” Beck said. “Horses are staying there year round, until the next gather.”
Reducing free-roaming horse numbers is divisive, even when herds are overpopulated and being reduced in the direction of federal goals. Roundups are monitored by impassioned wild horse advocates and management decisions are frequently litigated — including in portions of Beck’s study area.
Looking at his results, Beck’s main message to land managers is to strive to keep horse numbers lower than population goals.
“We’re not saying, ‘Get rid of all the horses,’” he said. “Our message is to manage it. If you manage it not to exceed that [goal], then sage grouse that share habitat with horses can continue to do well.”
The U.S. Geological Survey and University of Wyoming are building on the research. Biologists are trying to establish a direct link between what wild horse effects on nests, broods and juveniles means for sage grouse population growth rates, Milligan said. They’re looking elsewhere geographically, too.
“We’re hoping to expand the study outside of Wyoming,” she said, “to see how these relationships vary across sage grouse range.”
I believe that the horses are more important than a bird. But then I am a horse person. Not a bird person.
This should not be happening!!! The Sage Grouse will survive, the wild herds may not!!!! Stop this now!!!
“If there’s a problem with livestock, they take them off the range”? Seriously? Exactly when does that happen? Of course, with too many of ANY grazing animal – it would damage birds nesting on the ground – be it horses, cattle, sheep, deer, or ANY grazing animal. But of course only the horses are there all year round? Well, so are deer and other wildlife. I really doubt livestock are “taken off the range” to benefit wildlife – whether its birds or other animals.
I don’t believe the information in this article. I have followed the Horse conservative groups. I’ve seen the animal abuse served by helicopters. I have seen helicopters abuse other wildlife. Maybe it’s time to control humans with birth control and stop making Viagra. Humans are overpopulated the planet by several billion. Herds terrified by helicopters for miles, legs busted and dangling. Horrific and demeaning. Horses, and burros are not the problem. How much money does it take for 1 flight of helicopters? Roundup and sterilization! Bing bang boom. More jobs more incomes.
Interesting how the wild horses get blamed in pretty much every state. Herds can be managed by using birth control methods. But instead roundups are done and many horses are killed in the long run. Hurt from the roundups and how many are sent to slaughter at the auctions?? But because there’s no profit from wild horses they’re considered a nuisance.
The cattle are to blame for so much but because the cattleman’s association is so strong and cattle is a billion dollar business nothing is ever done. They keep breeding in order to keep up with this outrageous demand for meat and money!
The wrong people are running things.
I would like to know who paid for this study, and what they told the researchers they wanted the results to be. I have been on these ranges, and private livestock, mostly cows with calves, far outnumber wild horses. Those cows destroy riparian areas as well as over grazing.
It’s no surprise that impassioned wild horse advocate would dismiss and challenge this study out of hand with no backing evidence of their own. I was involved with wild horses in the southern third of Nevada for 30 years as a wildlife biologist. For Lee Sage to claim that the feral horses move around more than cattle is a complete fabrication. They are highly territorial and will chase other animals from water sources, particularly during drought. While the BLM is culpable, it is for being too soft on the horses, not being too hard. The AMLs are set for a range. You remove them to the lower limit and remove them in 4 to 5 years when they hit the upper limit. Except the BLM NEVER removes to the lower limit. They always start at the top and by the following spring, they are over the AML again. You can use ranchers and the BLM for whipping boys among yourselves, but it is nothing but fantasy. Your groups started suing a long time ago and they won a few cases, but the BLM is following the law and legal decisions now. Your groups win very few cases anymore. They are more holding actions that delay removals and result in more damage to the range. From what I have seen, the Wyoming BLM is doing a good job of feral horse management. Also, please quit bashing BLM personnel as if you were the only people who care. Those people take often thankless jobs because they care. The truth is that wild horse groups have never funded research that I know of counter the mounting research. The only reason for that that I can come up with is that you are afraid of what it would show. And while you’re at it, learn the law and the judicial decisions that shape management. Read the Act for what it says, not what you want it to say.
Just another biased report to support the BLM greed of taking wild horses off range nothing this teport says is true they are basing it off BLM figures which is a biased report to begin with. But yet all the cattle and sheep who destroy more than a horse ever does is ok. Horses never stay in one place long cattle on the other hand destroy where they are sheep to. How many cattle and sheep have been moved to these areas Im furious at the lies. To support there agenda. I wonder how much Wyoming was given for the so called unbiased research They are basing it off research so called research and numbers given to them by the BLM Thats wrong to begin with. Just another back door deal.
This is absolute rubbish! There are hardly any horses left! The livestock do much more damage.
The horses have been there forever, it’s not them that are the problem!
Lol, overpopulated humans are killing the world. Real life issues.
Well I wish you folks at WyoFile would stop spreading lies about wild horses, hoping that you can eliminate these beautiful animals for your own selfish reasons. I do wish that people would do a bit of research instead of just accepting the metric ton of garbage that the wealthy spread, exaggerating the numbers of wild horses on our public lands as a reason to remove them. These horses are native to Wyoming, Colorado, Nevada, and California to name a few and being eliminated way past numbers where they can thrive. The real culprits are the many thousands of cattle and sheep that cattle ranchers are paying pennies an acre to lease while the taxpayers foot the real bill.
Haven’t the wild horses been threw enough, and this for a grouse? When is the last time you rode a grouse?
I have a mustang, she has been with me for 18 years and I wouldn’t trade her for a grouse.
The feral descendants of European horses are not a native specie, but actually an invasive specie when they damage sage grouse survival.
Not true compare them to all the cattle and sheep on those lands now. Are they native
This “study” is too myopic to be considered scientific. For example, the researcher states that domestic livestock like sheep do less damage to sagebrush than horses. That is untrue. Sheep will eat sagebrush; horses will not. The definition of “overpopulation” offered by the BLM is also astonishing. Look it up sometime; it makes for hilarious reading.
I couldn’t agree more. When the BLM put in sage grouse protections and build their plan initially and was required to do reports when the sage grows habitat and brooding grounds were affected by fire or other influencing factors we as employees were told to ignore the effect cattle had on the habitat. Not completely but we weren’t allowed to say that the cattle were creating the issues for the habitat for the sage grouse even if it clearly was. I see nothing’s changed. Cheatgrasse exist on every acre on the east side of the Cascades largely due to cattle, which increases fire frequencies and intensities. Until the BLM and ranchers start taking the effects of cattle on the land seriously the high desert and the sage grouse communities are never going to recover.
Horses will eat sagebrush up to thumb width. Sheep don’t have top teeth. Every animal, if overpopulated can have detrimental effects.
Thanks for your reporting here Mike. We need information on how horses impact landscapes to best navigate decisions regarding their management.
More science which supports the BLM’s feral horse management efforts in SW Wyoming. Seems that studies of this type can be used as evidence in Federal court cases; and/or, the authors would qualify as admissible/credible witnesses supporting the BLM”s feral horse management approach. Nice to see best available science being published.
Thats not unbiased research. And everyone knows it. The research thats based on is biased to begin with. So now the BLM paid Wyoming to do research to fit their agenda How honest is that. Its not and every half intelligent person who has studied research and statistics knows it Its another scam to be used in court because you know there is growing unrest with what the BLM is doing Wow.
Great article Mike. I think I’d disagree with Jeff’s statement about livestock, however. Often we don’t go far enough when it comes to managing livestock, mostly due to politics. We can always do better.
Feral horses are of little use to anyone and are not wanted by anyone. There are too many and there is no good way to manage their numbers. They have no natural predators and can’t be hunted or rounded up and used for meat or any other product. We (all of us) public land owners need to continue to let our legislators and public land managers (USFS, BLM) know that we want fewer feral horses and more native wildlife.
Interestingly enough, the Sage Grouse have been nearly eliminated from the McCullough Peaks wild horse herd area in NW Wyoming. Not only have the too many horses pounded the landscape, the very same parcels of public land are also grazed by cattle. Sage Grouse can’t thrive in chronically overgrazed lands and especially in an area that is a 1 – 2 punch by both equine and bovine. Maybe I should address my concerns to the local Cody BLM office. Naw, that’s been done before (several times) and they don’t care
“Some 11% of the Equality State’s sage grouse habitat occurs within BLM herd management areas.” So, 89% of it doesn’t. Why focus on an area that represents so little of their habitat? “If there’s a problem with livestock, they take them off the range,” Beck said” Seriously, how can anyone say this with a straight face. Just how much and who sponsored the grant Mr Beck was given to perform this study. Yes, of course there will be a decline in one specie population when other species within the same environment increase. That’s a no brainer………
Great article. Wild horses, in my opinion, need to be removed from the landscape. They are having a too much of a negative impact on wild native species. I love horses, this is a terrible dilema.
While I love and have raised horses for most of my adult life, I definitely know how to many horses on acreage affect a lot of things! Horses hardly ever sleep, and they eat all the time they are awake. So as their numbers increase, the range grasses are definitely over stressed.
That’s total crap! Yes, horses need to eat almost constantly because their stomachs can only eat about 64 ounces at a time, whereas cattle have humongous stomachs and rip their food up by the roots with their tongues.
These studies are all flawed with zero proof. The damage you see in the West is caused by cattle and sheep. I live in an area without wild horses, sadly, and the free range cows and sheep destroy everything in their path.
Why don’t you do some better homework and stop listening to only the BLM and grazing associations and demand proof? What you’ve done is regurgitate the BLM’s public notices that have zero science in them. Show your work! This is absurd.
This really is crap!!! These poor wild horses can never catch a break !! They are cutoff from water in places , they are constantly rounded up. This is so inhumane !!!! And such animal cruelty !!! These horses should be taken care of in the range . The greedy ranchers punishment should be to take care of the horses . That would fix there wagon. What kind of human being would not like these beautiful creatures ! Only sociopaths would want to get rid of them .