Badger on Bear.

Sweet overpass. And it's used by more than bears:

"We’re able to demonstrate thousands and thousands of crossings every year, by 10-11 species of large mammals," Clevenger says. "We knew there were families of adult sows with cubs, adult female cougars with kittens using them. We knew that from the tracks. But the critics out there, some among transportation agencies, would say, 'Well it’s always the same male black bear that’s going back and forth.'"

To put this notion to rest, Clevenger and colleagues with Montana State University's Western Transportation Institute recently concluded a three-year study of the DNA from 10,000 hair samples of bears non-invasively snagged from the crossings and other areas around the park (the collection technology is not very sophisticated: this requires a little piece of barbed wire). DNA from bear hair is pretty amazing. It can reveal not just the difference between a black bear and a grizzly, but the identity of the individual bear, its gender, its relationship to bears of the same family.