Canada’s Overpasses Save Wildlife
When I was in Banff, Canada, my mind was a little bit blown by the highway overpasses. They look like any other overpasses, except they have a lush green trees and other vegetation on top. These overpasses, I learned, were designed as wildlife migration corridors.
The overpasses reduce animal-vehicle collisions (good for both animals and people) and allow wildlife to move freely among otherwise isolated areas. This movement helps keep gene pools healthy, preventing issues like developmental deformities, reduced reproduction rates, and risk of extinction.
A Controversial Idea With Massive Impact
When construction of these wildlife bridges first began in 1966, the project was met with skepticism, criticism, and even mockery—a “harebrained” scheme, and a waste of taxpayer dollars.
But the data tells a different story. These overpasses have reduced wildlife collisions with vehicles by more than 80%.
One initial skepticism was that animals could even be coaxed into using manmade bridges. Yet, wildlife cameras show that a broad variety of animals, including elk, bear, and small mammals like marmots, beavers, and wolverines use the crossings regularly. Research also shows toads, salamanders and snakes are using the crossings.
How Animals Know to Use the Overpasses
Well, for one thing, fencing is used to help funnel wildlife to the crossings. And some animals are earlier adopters than others. Deer and elk were the first to adopt in this case. For animals that are more wary, such as wolves or grizzly bears, it can take up to five years or more for them to use a new crossing.
No Single Solution for All Species
Interestingly, grizzly bears and elk tend to prefer the open sightlines of the overpasses. Meanwhile, camouflaged culverts, acting as wildlife underpasses, are favored by black bears and mountain lions who prefer long, low and narrow passage.
A Model for the World
Banff and its wildlife corridors have become a global model for countries looking to reduce wildlife deaths along roadways.
Biologists from countries like Belize, Argentina, and even Mongolia have visited Banff to learn more about implementing wildlife passageways. However, different species and ecosystems require different configurations, so continuous experimentation is needed to find what works best in each location.
The Bottom Line
Human activity, like highway construction, increasingly fragments natural habitats and the wildlife populations within them—and that’s a serious problem. Wildlife corridors, in all their forms, provide species with their best chance for long-term survival.
Sources
- Animal over- and underpasses are a huge conservation success story!
- As Banff’s famed wildlife overpasses turn 20, the world looks to Canada for conservation inspiration
Photo by WikiPedant at Wikimedia Commons