Animal crossings in Canada's Banff National Park allow bears to cross a major highway to breed, preventing genetic isolation.
Roads can fragment animal populations, increasing the risk of inbreeding and extinction. Bridges (pictured) and underpasses could help, but it has not been clear how well they work. Michael Sawaya and his colleagues at Montana State University in Bozeman studied grizzly bears (Ursus arctos) and black bears (Ursus americanus) that used 20 animal crossings along a 45-kilometre stretch of highway bisecting the park. The researchers snared fur samples from passing bears, using barbed wire and other devices, for DNA analysis.
Genetic data from bears using the crossings and those in the greater park area revealed a healthy amount of genetic exchange between populations on either side of the road.
Rights and permissions
About this article
Cite this article
Bears use animal bridges to breed. Nature 506, 410 (2014). https://doi.org/10.1038/506410a