Shane Moore has been documenting the natural world for nearly three decades, producing detailed studies of complex ecological problems around the world.

Before visiting Yellowstone National Park or "bear country" familiarize yourself with safety precautions in order to avoid bear encounters.

(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.

The NRDC has continued to push for greater protection for Yellowstone grizzlies, citing loss of habitat and food sources.

Segments from the NATURE episode "The Good, The Bad and the Grizzly" examine how human interaction with grizzlies has alternately endangered and restored the population, and how humans coexist with grizzlies today.

In this video-enhanced lesson, students will learn how human beings have interacted with and impacted the lives of grizzly bears in Yellowstone Park. (Grades 9-12)

Gray wolves are considered a "keystone" species -- one with a dramatic effect on its environment. For example, the recent reintroduction of gray wolves to Yellowstone National Park has led to the recovery of the entire ecosystem, from vegetation to beavers to hawks and eagles.

The original five members of the Druid Peak pack display early signs of the upheaval and drama that would eventually come to characterize the group.

Learn more about grizzly bears with these useful web sites and books.

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