Special wildlife crossings in the Canadian Rockies are saving bears’ lives, researchers say, and helping them reach their loved ones. According to a study published Tuesday in the journal Proceedings of the Royal Society B, grizzlies and black bears use underpasses that have been constructed under the Trans-Canada Highway and mate with animals on the other side.
Wildlife crossings, which can come in the form of both underpasses and overpasses, have been around for years. Large roads and highways can be problematic for wildlife, because they both provide the potential of collisions with cars, and tend to scare animals off, making their territories smaller. When animals are too scared to cross a road, they have a smaller pool of mates to choose from -- something that can harm the genetic diversity of the species. One study in 2000 found that many ungulate species like elk and deer used the crossings, while many carnivore species, like bears, were less likely to use them.
Now, the new study says that these crossings can work for bears, too. Using barbed-wire hair traps set up on highway underpasses and overpasses, the researchers sequenced the DNA from bears that passed through and compared the data with that of surrounding bear populations. And even better -- 47 percent of black bears and 27 percent of grizzly bears that used the crossings bred successfully.
Even more interesting is that the behavior seems to be increasing. Grizzlies used the crossings more and more from 1996 and 2008 -- likely because bear cubs are learning how to cross the street from their mothers.
Here are some other types of wildlife crossings used by conservationists: