Researcher seeks wider wildlife bridges

A black bear family crosses the highway in Canada. Credit: Liam Brennan

Canadian researchers measured wildlife overpasses around the world and found that 71% of them in North America were narrower than recommended.

These bridges allow bears and other creatures to cross busy highways, allowing animals to live and breed in their normal habitat; this is an important factor for biodiversity. Previous research has suggested a minimum width of 50 meters and a width-to-length ratio of 0.8 to ensure larger animals feel comfortable in transit.

wider is better

Researchers used Google Earth to measure wildlife overpasses. They counted 120, most of which are narrower than the native width guidelines. In North America, 20 out of 28 were narrower than 50 meters. They then analyzed camera data from 12 North American overpasses and found that wider overpasses had more animal crossings of more species per day than narrow ones.

“Overpasses are a win-win situation: they promote biodiversity and, along with other measures like fencing, save animal and human lives,” says UBC graduate student Liam Brennan. He says what is needed right now is localized guidelines for overpass sizes and monitoring to make sure they work for the animals they were designed for.

The research was published in the journal peerJ.

More information:
Liam Brennan et al., Wildlife flyover structure size, distribution, effectiveness and compliance with expert design recommendations, peerJ (2022). DOI: 10.7717/peerj.14371

Journal information:

Provided by the University of British Columbia

Quotation: Researcher calls for wider wildlife bridges (2022, 20 Dec) retrieved from on Dec 20, 2022

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