Bears on the Move

February, 2 2016  |  by kevin Back »

By Robb Krehbiel

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 Bear Migration

Grizzly bears will wander wherever they can find suitable habitat, regardless of what humans are already doing there. Figuring out where this habitat is can not only help better prepare people to live in harmony with bears, but it can also help prioritize conservation efforts to restore bears throughout their former range. While these two bear populations grow, conservationists are still concerned with small bear populations in the northwest Montana’s Cabinet Mountains and the Selkirk Mountains of north Idaho. An even bigger goal is to return bears to 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 the right places and make sure bears and people can share the land safely.

Grizzly Bear Linkage Zones

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 west of Missoula, Mont.

The Ninemile mountain range 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. Other researchers have suggested this same trip might be possible, but many challenges remain, not the least of which is Interstate 90. All along the southern border of the Ninemile is I-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.

Bears Crossing Interstate Highways

Highways and interstates cause obvious problems for wildlife. Habitat is lost when people build houses and communities along the road; the constant traffic can be enough to scare wildlife from trying to cross four or more lanes of traffic; and for the few animals that try, there’s the potential that a collision with a car will injure or kill them (not to mention people driving). Vehicle-wildlife collisions, especially with carnivores, are common along I-90. When looking at the number of carnivore carcasses picked up by Montana’s Department of Transportation, the vast majority are found along I-90.

Creating safe passage across I-90 is imperative, but challenging. Other projects in Montana have aimed to reduce vehicle-wildlife collisions by installing wildlife crossing structures and fences. These projects can keep bears off the road and funnel them safely through under and overpasses. On the Flathead Reservation, crossings structures along U.S. 93 North has 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 needs 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.

Wildlife Corridors

Vital Ground works with scientists to identify strategically-located private lands – the right places – that, if permanently protected, will help provide connections between large blocks of public land.

Vital Ground works with scientists to identify strategically-located private lands – the right places – that, if permanently protected, will help provide connections between large blocks of public land.

Protected Bear Crossing Areas

One place bears could use to safely cross I-90 is the area near the Ellis Mountain property, a conservation easement of 240 acres. Ellis Mountain has been protected thanks to a partnership between Vital Ground and father-daughter team Dave and Tina Petrig. (See the story on page 4.) 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.

The Ellis Mountain property can provide both secure grizzly bear habitat and guide the bears toward a safe crossing. This piece of property is currently Vital Ground’s only conservation easement in the Ninemile area. Given that private land borders almost the entirety of I-90, conservation easements that restore habitat, limit development, and guide bears to critical crossing points – the right places – will be an essential piece in encouraging movement across the interstate.

Conservation organizations need to increase their current efforts into key linkage areas that can protect grizzly bears as they expand back into their historic range. Further north of Ninemile, grizzly bears can move through the Salish linkage area. Following the Salish Mountains, bears can move through the linkage area from Glacier National Park to the Cabinet Mountains. This can help increase the size and diversity of 45-50 grizzlies that live in the Cabinet-Yaak. While highways also pose a challenge in the Salish linkage area, the biggest risk is an extremely high concentration of roads that still scar the land long after logging and mining operations have ended.

A Critical Linkage Area

The Coeur d’Alene Mountains can also provide habitat for bears moving from the Cabinet-Yaak Ecosystem into the Bitterroots. This linkage area is southwest of the Cabinet-Yaak and stretches south to I-90, where grizzly bears will still face challenges crossing the road. Road density is also a problem here. Decommissioning unneeded U.S. Forest Service roads and enhancing habitat on private land near interstates can establish a safe pathway for grizzly populations across the northern Rockies.

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.

Join Vital Ground to help preserve safe migration pathways for grizzlies and other wildlife.

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 in the summer of 2014. Prior to graduate school, Robb lived and worked in Seattle with an environmental nonprofit on wildlife and federal lands protection