Bear hair study in Banff proves animal highway crossings work
by Katie Mast
For three years, researchers from Montana State University spent their summers collecting bear hair. The samples, collected on both sides of the 50 mile stretch of the Trans-Canada Highway that cuts through Banff National Park, prove what the researchers had suspected: wildlife underpasses and bridges were helping enough bears move back and forth across the highway to keep the populations healthy.
The Trans-Canada Highway stretches nearly 5,000 miles across the country, rolling through each of the nation’s 10 provinces and connecting the Atlantic and Pacific coasts. The 100 miles that pass through Banff National Park is a blip in the entire stretch of highway, but a potentially deadly obstacle for the wildlife that live in the park. Demand for a bigger, faster road system prompted a widening of the highway in the 1990s. During construction, engineers lined the highway with fencing and built underpasses and bridges for animals to cross, with the theory they would reduce collisions and provide animals safe passage. However, the decision was controversial as there was little data to backup the hunch.
Construction of animal crossings has skyrocketed since they were first implemented in the 1970s, and Rob Ament, director of the Road Ecology Program at Montana State University says that research has shown as much as 80 to 90 percent decrease in vehicle-wildlife collisions in areas with the structures. Yet without proof that wide crossings are crucial to wildlife, planners have been reluctant to keep building them, especially overpasses, which are more costly and time-consuming than underpasses. MSU’s bear hair study proves that not only do animal crossings benefit humans, but also that both underpasses and the more expensive overpasses may be critical to some species' survival.
While deadly run-ins with vehicles is a gruesome end for many animals, the fate of about 1 million vertebrates each day, fragmentation of habitat has brought some species near extinction. Whether unable or unwilling to cross a road, animals living on one side that can’t encounter animals on the other side means isolation of genes, what biologists call the “island effect.”
The crossings in Banff National Park include two wide overpasses covered in vegetation that helps them resemble the surrounding habitat. Underpasses provide the cover cougars and many small mammals need, while the bridges and overpasses let moose and elk traverse in their preferred open-sky habitats. Cameras at each of the passageways have recorded hundreds of thousands of crossings for many different species, including bears, wolves, lynx, deer, elk and moose. A wolverine made the news when a camera captured its walk across an overpass, becoming the first such venture recorded for its species. But cameras couldn’t help scientists collect data about individual crossings. “We could show that there were a lot of crossings, but what did that mean?
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For more on Safe Passages, check out the book.
Safe Passages: Highways, Wildlife, and Habitat Connectivity; Edited by Jon P. Beckmann, Anthony P. Clevenger, Marcel P. Huijser, and Jodi A. Hilty