Most recently, a bear was shot in northern Canada that didn't quite fit the polar bear description.
Its head was the same shape as a grizzly bear and its paws were brown, hunter Didji Ishalook told CBC News.
The reason for the crossover? The bears would rather mate with a different kind of bear than not mate at all, the Washington Post reports. But that's not necessarily great news for the future of the polar bear, which needs Arctic ice to thrive.
"I hate to say it, but from a genetic perspective, it's quite likely grizzly bears will eat polar bears up, genetically," University of Alberta professor Andrew Derocher told the Post. The warmer temperatures have led to expanded territories for the grizzlies to roam and run into polar bear mates, which could lead to polar bears as we know them to dissolve into the grizzly population.