Mountain lion, black bear, and coyotes caught with a motion-sensing camera using a U.S.-93 wildlife underpass in Montana
One summit presentation touched on U.S.-93, which hosts one of the world’s largest networks of wildlife crossings. Built north of Missoula on the Flathead Indian Reservation, the crossings came about as a partnership between MDT, the Confederated Salish and Kootenai Tribes, and the Federal Highways Administration. The north-south U.S.-93 highway unfortunately bisects one of Montana’s prime east-west wildlife migration corridors and runs through large expanses of wildlife habitat, including the Mission Mountains, the Bob Marshall Wilderness Complex, and the Selway-Bitterroot Wilderness Area, making these crossings sorely needed.
“We built an entire interstate system and other superhighways without considering the needs of wildlife,” WTI’s Ament says. When bisected by roadways and other impediments, some animal populations can become genetically isolated, as noted in a study of grizzly and black bear populations on either side of the Trans-Canada Highway in Banff National Park, the site of one of the most extensive networks of animal crossings in the world. Its 42 underpasses and 7 overpasses are used by bears, elk, cougar, mountain goats, and wolves.
Some animals are initially wary of any artificial crossing structure. Research cameras have recorded animals approaching tunnels and bridges, then running away at the sound of a vehicle. But, says Ament, “over time, they realize the bridge isn’t going to hurt them, and slowly, over the years, the bridge becomes quite normal, and adults teach their young about it.”
A study conducted by Montana State University researchers in collaboration with WTI showed that crossings enhance the access of both black bears and grizzlies to potential mates, and thus keep populations from being genetically isolated. Through parentage tests, the study revealed that 47 percent of black bears and 27 percent of grizzly bears that used crossings were able to breed successfully.
The increasing availability of migration data tracking the preferred routes of individual populations is a recent addition to the researcher’s toolbox, one that can help support the efficacy of bridge-and-tunnel animal pathways. “We’ve learned so much about wildlife migration in the past 10 years with GPS collars coming online,” says Chris Colligan, wildlife program coordinator with the Greater Yellowstone Coalition (GYC).
Some grizzlies in the state are radio-monitored, and these imperiled bears are among the species that stand to benefit from road crossings in Montana. “Improving grizzly bear connectivity will require building safer and more permeable corridors that bears can move through, especially considering the alarming number of bears killed by vehicles and other human causes last year,” says Sherry.
But do these various wildlife accommodations really reduce human–animal collisions? Researchers pointed out in one study that Banff fencing reduced ungulate–vehicle collisions by 80 percent. Studies from WTI found that overall, collisions declined dramatically near U.S.-93’s fish and wildlife crossings, where long stretches of fencing prevented animals from attempting to cross roads. But where there were gaps in fencing at road access points, animal–vehicle collisions remained high, as researchers expected.
Indeed, the collision death of a mama grizzly and her two cubs, animals listed as “threatened” under the Endangered Species Act, made headlines last summer. It happened along a stretch of U.S.-93 not yet overhauled, and without overpasses.
Alternatives to bridges and tunnels include monitoring systems that alert drivers to the possibility of encountering an animal at a wildlife “crosswalk.” Other solutions are far more low-tech, including the use of fencing or vegetation management to influence animal movements, or signage to warn drivers passing through high-risk areas. For the best result, notes Sherry, tools like these should be used in combination, for the sake of wildlife and human safety alike.
Power of Partnerships
State transportation departments are concerned about the logistics and costs of crossing maintenance, according to Ament. For example, if a tree falls and takes down part of a fence, who pays to replace the fencing when state, federal and interagency organizations may have overlapping jurisdiction over the given land, not to mention private property owners?
At the conference, Ament offered a presentation on partnerships, which may be key to the progress of corridors and crossings. In Montana, coalitions of nonprofits, land trusts, hunter and angler groups, local businesses, and counties are creating and sustaining crossings. The organization Vital Ground, a foundation dedicated to grizzly bear conservation in the Northern Rockies, has purchased Montana land parcels near some road crossings, connecting grizzly bear habitat that was once fragmented.
Communities have a role to play as well, by alerting researchers and state officials where animals are frequently seen or hit. Individual citizens are also getting involved: In Montana, one local rancher provided a land easement so MDT could install an underpass at a popular wildlife crossing point. As a side benefit, his cattle also use the underpass en route to grazing opportunities.
Wildlife crossings are taking shape in other Rockies states as well. In 2017, Wyoming started a two-phase, $100 million project to reconstruct a section of U.S. Highway 89, just south of Jackson. Part of the project, 17 years in the making, is to build six underpasses for wildlife, two fish passages, and numerous culverts for smaller animals. And both GYC and Montanans for Safe Wildlife Passage have encouraged wildlife-safe fencing for landowners.
Highway overpasses and underpasses are good not just for the animals, notes Renee Callahan, senior policy analyst at the CLLC and a summit panelist. Siting wildlife infrastructure at wildlife-collision hot spots creates “a win-win-win,” she says. “You save peoples’ lives, you save animal lives, and you save taxpayer money.”
“To me, the beauty of this issue is that there’s something about it that resonates for almost everyone,” Callahan says, from taxpayers to hunters to wildlife conservationists. “Public awareness is so important,” she adds. “Once people understand the solution is available, it’s really amazing how wildlife crossings can generate support in communities.”
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