This grizzly bear is not sleeping. She's been in a state of hibernation since November.

Intelligent, adaptable and fierce, the polar bear learned how to survive in a place that offers few comforts to any creature.

When a bison goes down, grizzlies vie for control of the carcass. Ravens and wolves call for reinforcements.

In the vast and complex kingdom of Yellowstone, two dominant predators reign supreme: the grizzly bear and the wolf.

To film a bear in hibernation, NATURE took on the challenge of creating a den which would resemble one a grizzly would make in Yellowstone.

Select an animal name to see where each animal can be found within the park.

NATURE presents a breathtaking look at wintertime deep within Yellowstone, America's first national park.

The walls of ice in Glacier Bay surround the most beautiful sights Alaska has to offer. Watch the full episode online.

In Yellowstone National Park, two predators reign supreme: the grizzly bear and the wolf. Watch the full episode online.

Watch the full episode of The Good, the Bad, and the Grizzly online now.