Snowy probably never knew what hit him. Last month, a motorist in Grand Teton National Park killed the lone cub of the internet-famous Grizzly 399 as the pair crossed the road at Pilgrim Creek—a popular spot for wildlife watching. In the last 20 years, Grizzly 399 has become one of the most photographed bears in the world, due to her penchant for hanging out along a busy roadside; she had found that it was a safe haven to raise her cubs away from aggressive male grizzlies and wolf packs. Wildlife lovers were distraught at the news that her cub, dubbed “Snowy” due to his blonde facial fur, died in what park officials are calling a hit-and-run.
If the news was awful, it was also ordinary. Each year, at least 1 million animals in the United States are killed by automobiles. The actual number is likely many times greater than that, as drivers rarely report deadly collisions with smaller animals such as skunks, raccoons, and squirrels.
Biologists say that human civilization’s ever-expanding network of roads—along with increased traffic—represent one of the greatest threats to maintaining healthy and robust wildlife populations. Many species of wildlife need space to roam in order to find food and locate mates. But our highways and interstates present dangerous, if not insurmountable, obstacles to wildlife migration, leaving some populations of animals isolated in pockets of wildlands. Such isolation reduces species’ genetic diversity, and can even contribute to localized extirpations.
“It’s an enormous problem, especially on high-traffic roads,” says Paul Beier, a professor in the School of Forestry at Northern Arizona University who has published widely on the issue of wildlife migration. “A low-traffic road is not a barrier to most animals, but for some animals, like pronghorn, it can be a complete barrier.”
Beier says that when many of our road networks—especially the interstate highway system—were planned 50 or 60 years ago, transportation officials didn’t consider the effects on wildlife migration. Since then, conservation biologists have developed a deeper understanding of wildlife connectivity, leading to a push, belated though it may be, to retrofit roads with underpasses or overpasses for critters to cross. “Basically, to make sure these wildlife populations survive, we need to make sure they are connected with safe corridors,” Beier says.
This isn’t rocket science. As prosaic as it may sound, something as simple as a bridge over a road can be vital for ensuring that wildlife is able to thrive.