As the grizzly bears of Yellowstone settle into their winter hibernation, the debate concerning their future will remain decidedly active.

The Endangered Species Act helped save Yellowstone's grizzly bears from extinction, but that doesn't mean the great bears are out of the woods.

Although the gray wolf remains an endangered -- and therefore protected -- species, wolves nevertheless face the same risks as any other animal species.

Cheetahs face tough challenges in the natural world, and the survival of the species is in doubt. So what makes a successful cheetah rehab program?

One of India's most magnificent and endangered animals fulfills its destiny in a remote nature preserve that also shrouds the ruins of a long-fallen empire.

To help ensure the survival of endangered whooping cranes, Operation Migration maintains an artificial breeding program that prepares chicks for adulthood.

What would it feel like to stumble upon an animal that was feared by biologists to be extinct? Russell Thorstrom knows -- he's done it twice.

Biologists trying to restore eagle populations around the world face a difficult challenge. But there are success stories -- and the restoration of America's Bald Eagle is one of the most dramatic.

The world's nearly 300 turtle species have a remarkable range of behaviors, from wood turtles that stomp the ground to attract worms, to sea turtles that travel thousands of miles to lay eggs.