Once the genetic testing was finished, Sawaya said they could identify 15 individual grizzly bears and 17 individual black bears that used the highway crossings over the three years, which Sawaya said paints a good picture of the demographic connectivity provided by the crossing structures. During the study, close to 20 percent of the grizzly and black bears in Banff used the crossings. Grizzlies were more likely to use the overpasses, while black bears were more likely to use underpasses.
Sawaya said research shows that movement of more than 10 percent of a population through the highway barrier signals there is sufficient connectivity to maintain a healthy ecosystem for bears and other large mammals.
Clevenger, who has been tracking the numbers of bear crossings on the Trans-Canada Highway crossing structures for over a decade as part of the Banff Wildlife Crossings Project, said the study's findings are a breakthrough.
"This is confirmation of what our previous investigations have suggested but couldn't confirm," Clevenger said. "We were pretty certain that the numbers of bears using the crossings had steadily increased. Now we know."
The use of wildlife crossings to protect motorists and wildlife on the Trans-Canada Highway in Banff has been a model for similar projects elsewhere. WTI has been consulting on proposed projects with similar goals in countries around the world, from Mongolia, to China, to Brazil.
In Montana, where U.S. Highway 93 runs through the southern Flathead Valley, it runs near prime grizzly bear habitat in the Mission Mountains and the Bob Marshall Wilderness complex. At the request
|Contact: Evelyn Boswell|
Montana State University