Fortress of the Bears filmmaker Shane Moore on some of the filming techniques he used during his shoot on Alaska's Admiralty Island. A behind-the-scenes look at what goes into the making of a nature documentary.

After a spring and summer with no sign of salmon, a mother bear is desperate to catch fish to feed her famished cub. Watch video.

Enter a world shaped by bears, trees, and salmon, and explores the delicate balance of their interconnected lives. Watch a preview of PBS Nature's Fortress of the Bears.

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

It’s finally here — time for us to share our incredible Alaskan adventure with the world through Bears of the Last Frontier. It has been quite the journey. The film has been nearly two years in the making, and for both of us it has become an unforgettable part of our lives

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

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

(Airs Sunday, September 13) NATURE's The Good, the Bad and the Grizzly looks at the grizzly bear's remarkable recovery and examines the controversy behind the conservation success story.

Follow Ewan Mcgregor as he travels to a remote Canadian outpost on Hudson Bay, where he investigates the annual invasion of hungry polar bears.