Are There Grizzly Bears in the Bighorn Mountains?

Grizzly bears do not currently maintain an established population in Wyoming’s Bighorn Mountains. No breeding females or resident groups have been documented there, and the range is not included in any federal recovery zone. That said, the Greater Yellowstone Ecosystem’s grizzly population has been expanding steadily for decades, and the occupied range has grown so dramatically that individual bears, particularly young males looking for new territory, have been turning up in places they haven’t been seen in a century. The Bighorn Mountains sit tantalizingly close to that expanding frontier, making the question less about whether grizzlies are there now and more about whether they could arrive in the foreseeable future.

The Expanding Edge of Grizzly Country

To understand why the Bighorns even enter the conversation, you need to appreciate how much ground Greater Yellowstone’s grizzlies have reclaimed. The population hit a low of roughly 136 animals in the 1970s, prompting Endangered Species Act protections and intensive management. Recovery worked. The estimated occupied range grew from about 9,020 square miles in 1990 to roughly 27,066 square miles by 2022, a threefold increase in just over three decades.¹ Between 2004 and 2010 alone, distribution expanded by about 38 percent, with most of that growth happening on the northern and southern edges of the range.²

That outward push means grizzlies have been showing up in areas of Wyoming, Montana, and Idaho where they hadn’t been seen since the early twentieth century. They’ve moved into the Wind River Range to the south, parts of the Wyoming Range, and areas east of the Absaroka Mountains. Dispersing males have been confirmed in locations well outside the historic recovery zone. Each time the occupied range map is updated, the eastern boundary creeps a little closer to the Bighorn Basin, the broad, arid lowland that separates the Absaroka-Yellowstone highlands from the Bighorn Mountains.

The Bighorn Basin Problem

Geography is the biggest reason grizzlies haven’t colonized the Bighorns despite decades of population growth. The Bighorn Basin is a wide stretch of low-elevation, semi-arid terrain lying between the Absaroka Range on the west and the Bighorn Mountains on the east. Towns like Cody, Greybull, and Worland dot the basin floor. Irrigated agriculture fills the valleys. Interstate highways, state roads, and ranch fences crisscross the landscape. For a grizzly, crossing the basin means leaving the security of high-elevation forests and traversing open, human-dominated country with little cover.

Research on grizzly survival in the Greater Yellowstone Ecosystem has repeatedly identified roads and human development as the primary threats to individual bears. A study modeling survival hazards found that grizzly bear survival improved as secure habitat and elevation increased but declined as road density, number of homes, and site developments increased within a bear’s home range.³ The Bighorn Basin concentrates exactly the kind of landscape features that reduce a grizzly’s chances of surviving a crossing: low elevation, high road density, towns, and livestock operations.

This doesn’t mean a bear could never make it across. Young male grizzlies are famous for their long-distance dispersal attempts, sometimes covering dozens of miles in a few days. But a single bear passing through is very different from a population establishing itself. For grizzlies to take hold in the Bighorns, females would eventually need to cross or be born on the far side, and females disperse far shorter distances than males. A lone male wandering through the Bighorns would be a notable wildlife event; a breeding population would require sustained connectivity that the basin currently does not provide.

Mountain Ranges as Stepping Stones

Connectivity research has explored how grizzly bears might move between isolated populations by hopping along chains of mountainous habitat. A study modeling potential dispersal paths found that where landscape features concentrated movement into corridors, those corridors typically followed neighboring mountain ranges, with several ranges identified as pivotal stepping stones.⁴ The concept is straightforward: bears prefer forested, mountainous terrain with good food sources and limited human disturbance. If a string of suitable mountain ranges connects two distant areas with only short gaps of unsuitable habitat in between, bears can island-hop from one to the next.

The Bighorn Mountains, viewed through this lens, are a potential destination but one separated from the GYE by a gap that’s wider and more hostile than the gaps between most stepping-stone ranges farther north. The Absaroka Range and the Bighorns are not joined by a forested corridor. Riparian zones along rivers like the Bighorn, Greybull, and Shoshone rivers provide strips of cover through the basin, but those same riparian corridors are flanked by agricultural land, and the proximity of livestock substantially increases the chance that a bear using them will come into conflict with people.⁵ A grizzly following a river bottom through ranch country is a grizzly that’s likely to encounter cattle, sheep, and, eventually, a management response.

Lessons from the Northern Continental Divide

If connecting the GYE to the Bighorn Mountains sounds difficult, consider how hard it has been to connect the GYE to a much closer grizzly population: the Northern Continental Divide Ecosystem in northwest Montana, centered on Glacier National Park. Only about 110 kilometers (roughly 70 miles) separates the current estimated edges of these two populations.⁶ That gap is narrower than the Bighorn Basin, runs through more mountainous terrain, and has been the focus of dedicated conservation efforts for years. Yet genetic analysis has found no evidence of natural movement between the two populations; every sampled bear was correctly classified to its population of origin, confirming that the GYE population remains genetically isolated.⁷

This is a sobering comparison for anyone hoping grizzlies will naturally recolonize the Bighorns. If the GYE bears haven’t yet established gene flow with a large population just 70 miles to the north across relatively favorable terrain, the odds of them sustaining a presence in the Bighorns, which lie across a wider and less hospitable gap, are quite low under current conditions. That doesn’t rule out the occasional wanderer, but it puts a realistic frame around the timeline for any permanent return.

What Occasional Sightings Actually Mean

From time to time, reports surface of a grizzly bear spotted in or near the Bighorn Mountains. These reports are understandably exciting, and they aren’t impossible to believe given the population’s expansion. But they need context. Wildlife agencies distinguish between a confirmed sighting, which involves physical evidence like tracks, hair, photographs, or a GPS-collared animal, and an unconfirmed report, which is an observer’s account that hasn’t been verified. Most “grizzly in the Bighorns” reports fall into the latter category. Grizzlies and large dark-furred black bears can look strikingly similar at a distance, and the Bighorn Mountains do have a healthy black bear population. Misidentification is common enough that agencies treat uncorroborated visual reports with caution.

Even verified sightings of individual bears outside the established range don’t mean a population exists. Young male grizzlies sometimes undertake remarkable journeys. Bears have turned up on the Great Plains of Montana, in Nebraska-adjacent corners of South Dakota, and in agricultural valleys far from any mountain forest. These are dispersal events, not range establishment. A population requires females raising cubs in a given area over multiple generations. Until that is documented, the Bighorn Mountains remain outside the grizzly’s functional range regardless of how many individual males pass through.

Could the Bighorns Support Grizzlies If They Arrived?

The habitat itself is actually promising. The Bighorn Mountains rise to over 13,000 feet, with extensive subalpine forests, alpine meadows, and numerous streams. The Bighorn National Forest covers over a million acres. Whitebark pine, a historically important food source for Yellowstone grizzlies, grows at high elevations in the range. Berry-producing shrubs, root-digging meadows, and ungulate populations are all present. In terms of raw habitat quality, the Bighorns could plausibly sustain a small number of bears.

The limiting factor isn’t food or terrain; it’s getting there and staying connected. An isolated population of a few bears in the Bighorns would face many of the same genetic bottleneck risks that the GYE population itself once faced during its low point in the 1970s. Without periodic immigration from the broader GYE or Northern Continental Divide populations, a Bighorn grizzly population would be at risk of inbreeding and demographic collapse. The mountains, though large enough to support bears seasonally, probably aren’t large enough to support a self-sustaining population over the long term without immigration. This is the same island-biogeography problem that drives connectivity research for grizzlies across the entire Northern Rockies.

What This Means If You’re Heading into the Bighorns

For hikers, hunters, and backcountry travelers in the Bighorn Mountains, the practical question is whether you need to worry about grizzly bears right now. The honest answer is that your risk is extremely low compared to someone hiking in Yellowstone or the Absaroka-Beartooth Wilderness, where grizzly density is much higher. Black bears are the species you’re realistically likely to encounter in the Bighorns, and the safety precautions for black bears overlap heavily with grizzly precautions anyway: store food properly, make noise on the trail, don’t approach wildlife.

That said, carrying bear spray is a reasonable habit for anyone spending time in the backcountry of the Northern Rockies, even in ranges where grizzlies aren’t established. Research in the Greater Yellowstone Ecosystem found bear spray has roughly a 92 percent efficacy rate at stopping or reducing the severity of aggressive bear encounters.⁸ Despite that track record, a survey of visitors across the GYE found that about 27 percent reported never carrying bear spray, with non-carriers tending to be first-time visitors or day-use visitors in front-country areas.⁹ If grizzly range continues to expand eastward, the people least prepared for an encounter are often the ones most likely to find themselves in newly occupied territory.

Bear spray works on black bears too, and it’s lighter than a firearm. For Bighorn Mountain recreationists, it’s cheap insurance against an event that is improbable today but may become less so over the coming decades. Developing the habit now, rather than after a confirmed grizzly shows up in the range, is the more sensible approach.

Livestock and the Conflict Frontier

One reason wildlife managers pay close attention to the eastern edge of grizzly expansion is the density of livestock operations in the foothills and basins east of the Absaroka Range. The Bighorn Basin is cattle and sheep country. If grizzlies begin moving through the basin with any regularity, conflicts with ranchers are virtually guaranteed. Research has shown that the likelihood of human-grizzly conflict rises sharply as the distance to cattle or sheep pastures decreases; a reduction of just one kilometer in the distance to active grazing land substantially increased the odds of conflict across spring, summer, and fall seasons.⁵

This matters for the Bighorn question because any natural recolonization would require bears to pass through exactly the kind of landscape most likely to produce deadly encounters, not for the hikers, but for the bears. A grizzly that kills livestock in the basin is a grizzly that will almost certainly be removed by management agencies, either relocated or euthanized. Each bear lost during a basin crossing is one fewer potential colonizer. The conflict landscape between the GYE and the Bighorns acts as a filter, allowing occasional passage but making sustained movement very difficult.

Some conservation advocates have proposed wildlife corridors, highway crossing structures, and grazing practice changes that could, in theory, reduce this friction. Programs that compensate ranchers for livestock losses or fund range riders to keep bears and cattle separated have shown promise in other parts of grizzly country. Whether the political will and funding exist to extend those programs across the Bighorn Basin is another question entirely, and one that depends on public attitudes toward grizzly recovery in communities where the bear is not always welcome.

The Role of Roads and Highways

Beyond livestock, roads pose their own barrier. US Highway 14/16/20, which runs east from Yellowstone through the Bighorn Basin, carries heavy traffic and passes through towns and developed areas. Interstate-level roads aren’t common in this part of Wyoming, but even two-lane highways with moderate traffic volumes can deter large carnivore crossings. Grizzly survival research has consistently identified road density as one of the strongest predictors of mortality, with bears in road-heavy home ranges dying at higher rates than those in more remote areas.³

Roads kill bears directly through vehicle collisions and indirectly by increasing the probability that a bear will encounter a person, a dog, or an unsecured food source that leads to habituation and eventual removal. For a dispersing grizzly moving east from the Absarokas, every mile of road crossed in the basin is another roll of the dice. The cumulative effect of multiple road crossings, combined with the agricultural conflicts described above, means the basin functions as a semi-permeable barrier: not an absolute wall, but a landscape where the odds are stacked against successful passage.

How Climate Change Could Shift the Picture

One wildcard in the long-term outlook is climate. Warming temperatures are changing vegetation patterns across the Northern Rockies. Treeline is creeping upward in some areas. Whitebark pine, once a critical fall food for Yellowstone grizzlies, has been devastated by bark beetle outbreaks linked to warmer winters. As traditional high-elevation food sources decline or shift, grizzlies have been spending more time at lower elevations and in new habitats, which partly explains the range expansion already observed.

If warming continues to push bears toward new food sources at new elevations, the pressure to expand could intensify. At the same time, climate change could alter the Bighorn Basin itself, potentially making it more or less hospitable as a crossing zone. Wetter conditions might improve riparian corridors; drier conditions might make the basin even more barren and exposed. Predicting how these changes interact is difficult, and the research community is candid about the uncertainty. What seems clear is that the static picture, with grizzlies confined to the GYE core and the Bighorns permanently out of reach, is less stable than it once appeared. The map keeps changing, and the bears keep pushing at its edges.