Wildlife Crossings

2021-06-04

 |  Biodiversity/Conservation

Humans and animals have always cohabited on earth. Unfortunately, as you probably know, human activities and human-built environments are increasingly encroaching on animals’ habitats. This leads to two main issues: a rising number of interactions between wild animals and us and fragmentation of habitation zones. Some interactions have little effect, while others are devastating to animals, including car collisions, loss of habitats, and disrupted migration patterns. To mitigate the negative effects that large roadways, railroads, and canals have on animals, wildlife crossings are being built. They also help prevent potentially deadly car collisions for humans which have increased by 50% in the last 15 years. 

Wildlife crossing is a general term that describes a structure built to connect habitats otherwise disrupted by human-made barriers. First developed in France in the 1950s, there are now thousands of wildlife crossings globally as the idea gains traction. They are specifically built to match the surrounding landscape by incorporating native plants and blending into the environment. They are also specially adapted to the specific needs of local wildlife. For example, amphibians and small mammals are more likely to use tunnels, while overpasses and bridges are better for large mammals. Wildlife crossings can take many different shapes, including green roofs, overpasses, underpasses, bridges, ecoducts, viaducts, culverts, and tunnels.

There are a few considerations to take into account when building wildlife crossings. The animals need to feel safe on the crossing, so the landscaping and size must be well suited to the local species. The crossings also need to be placed in the right areas. In the Snoqualmie Pass project in Washington State, animals were monitored for five years to determine where they crossed the road most. All of this necessitates extensive research and planning. Once the crossings are built, there are varying learning curves for each species, depending on how accustomed they are to human structures and what sort of fencing there is to guide them to the crossing. One huge asset to the structures is that once they are well established, wildlife are able to teach their young where to cross. This is one of the best ways to preserve ecosystems! 

There are of course financial considerations as well. It is easier and less expensive to build these wildlife crossings while the road is being built, rather than through retrofitting. Developing nations building expansive roads can take advantage of the cost savings when building wildlife crossings, like Bhutan is doing by creating bridges for wild elephants. Overall the mitigation efforts will be more expensive in places like North America and Europe. However, decreasing accidents between animals and humans saves a lot of money. 

One of the most successful systems follows the Trans-Canada Highway in Banff National Park, Alberta. Since 1996, 44 structures, composed of six bridges and 38 underpasses, have been built. Officials have documented over 150,000 animals such as elk, moose, black bears, grizzly bears, and cougars using the wildlife bridges. There has been an 80 percent reduction in motor accidents involving wildlife due to these bridges and underpasses. An additional benefit is that due to the increased habitat size, grizzly bears in Banff have a wide enough selection of mates to stabilize their genetic flow. Clearly, the wildlife crossings have had a substantial positive impact on both animals and humans. 

It is difficult to limit the spread of human-built environments in today’s world. However, wildlife crossings are able to reduce car and animal collisions as well as expand habitats, food sources, and genetic diversity for many species. With research and planning, they can make a huge difference in Canada and throughout the world. To find out more about wildlife crossings in Canada visit the Parks Canada website.