Bears Need Highway Overpasses, Too

Beautiful Banff National Park in Canada began to install the first of several dozen underpasses and overpasses across the Trans-Canada Highway inside the preserve's boundaries in the 1980s. They connect on either side of the four-lane road to no sidewalks or trails. And they've never been marked on hiking maps of the park used by tourists. "We don’t advertise them," says Tony Clevenger, a wildlife biologist who's been working in the park for 17 years.

They look, for the most part, like typical pedestrian infrastructure: elliptical or boxy concrete culverts under the highway high enough for a human to pass through, or overpasses that would look entirely familiar to the vehicles passing below. All this highway engineering, though, is meant for the benefit of bears. And cougars, and wolves, and elk.