Permeability of the Trans-Canada highway to Black Bear movements in the Bow River Valley of Banff National Park
I compared the effects of four parallel linear features on black bear (Ursus americanus) movements in the Bow River valley of Banff National Park. Three linear features were transportation routes (in decreasing order of vehicle-traffic volume: Trans- Canada highway, 1A scenic highway, Canadian Pacific railway [CPR]), and the fourth was the Bow River, a natural linear feature. Radio-fitted bears were monitored over two sampling periods (six bears in 1987-88 and 13 bears in 1996-97), during which
... 6-97), during which time vehicle traffic increased by 13-24%. I compared bear movements to a spatial simulation to determine if bears crossed the linear features less than what would be expected by random chance. There was an inverse relationship between the permeability of linear features and traffic volumes of those features. On an individual basis, 37% of the bears crossed the Trans-Canada less than what would be expected by random chance, compared to 13%, 16%, and 11% for the 1A, CPR, and Bow River, respectively. When the two sampling periods were compared, CPR permeability was significantly higher in 1996-97. For female bears, age or experience was a better indicator of Trans-Canada permeability than habitat. Learning to use wildlife crossing structures appeared to play an important role in determining the success of Trans-Canada crossings. I recommend using techniques that encourage bears to learn to use wildlife crossing structures, which will have the dual effect of maintaining permeability and reducing vehicle-wildlife collisions.