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Bears on the Move
Wildlife connections

Bears on the Move

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After decades of conservation work from countless individuals, grizzly bear populations are growing in and around Yellowstone and Glacier National Parks.

As populations grow, though, bears require more space. And when an animal weighs over 400 pounds, it’s hard to tell it where to go. Grizzly bears will wander wherever they can find suitable habitat, regardless of what humans are already doing there.

Figuring out where this habitat exists can not only help prepare people to live in harmony with bears, but can also help prioritize conservation efforts to restore bears throughout their former range. That includes the Bitterroot Mountains in central Idaho, a place where grizzlies vanished decades ago. If we can figure out where these bears might go, we can protect habitat and make sure bears and people can share the land safely. 

Figuring that out is easier said than done, and it’s what I spent last summer trying to do. Working as an intern with Defenders of Wildlife, I mapped out places where grizzly bears might roam. What I found were several linkage zones; stretches of land with some of the best remaining habitat for grizzly bears and other wildlife as they move across the landscape. Looking at these linkage zones, there were several possible pathways that bears could use to move from their current range and into the Bitterroots. One of the most important of these linkage areas was the Ninemile area just northwest of Missoula.

The Ninemile Divide provides lots of habitat for bears. My research suggests that there is suitable habitat for bears to move out of the Mission Mountains, north of Missoula, into the Ninemile mountains, and then south to reach the Bitterroots.

Many challenges remain, not the least of which is Interstate 90. This high-traffic motorway, lined with development, acts like a wall for grizzly bears and other wildlife. Establishing a clear pathway into the Bitterroots requires making I-90 an easier road to cross.

Highways and interstates are problematic for wildlife, and I-90 appears to be one of the worst. Vehicle-wildlife collisions, especially with carnivores, are common along I-90. The vast majority of carnivore carcasses picked up by Montana’s Department of Transportation are found along I-90.

Other projects in Montana have aimed to reduce vehicle-wildlife collisions by installing wildlife crossing structures and fences. On the Flathead Reservation, crossings structures along U.S. 93 North have substantially decreased the number of car-wildlife collisions. Researchers have even captured photos of grizzly bears using underpasses. Unfortunately, these projects are expensive, and many private landowners aren’t too keen about tall fences lining their property.

Even with fences and crossing structures, projects still need to ensure that there is plenty of good habitat on both sides of the highway. Subdivisions, exurban homes, and suburban sprawl along I-90 continue to decrease available habitat. To safely cross interstates and highways, wildlife need secure habitat leading to safe crossing locations. While not many of these places exist, I found a few narrow strips of land that may be able to facilitate some movement across I-90.

One place bears could use to safely cross I-90 is the area near the Ellis Mountain property, a 240-acre conservation easement recently protected by Vital Ground. The property is situated at the confluence of the Ninemile and Clark Fork Valleys. Here, the Clark Fork River passes underneath I-90, and the interstate’s overpasses are large enough that wildlife can safely pass under the road on their way south to the Bitterroots.

While this property can provide both secure grizzly bear habitat and guide the bears toward a safe crossing, it is Vital Ground’s only conservation easement in the Ninemile area. Given that private land borders almost the entirety of I-90, conservation easements will be an essential piece in encouraging movement across the interstate.

As bear populations continue to grow, it is increasingly important that we secure and improve habitat where bears can safely roam. Multiple linkage areas exist throughout Montana and Idaho, each with its own set of challenges. Careful planning, innovative projects, collaborative management, and changing attitudes can enhance these linkage areas and restore grizzly bears throughout the West.


Robb Krehbiel is an M.S. candidate in sustainable development and conservation biology at the University of Maryland. His connectivity research was conducted out of Defenders of Wildlife's Missoula office. Prior to graduate school, Robb lived and worked in Seattle with an environmental nonprofit on wildlife and federal lands protection.

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