Yellowstone is a hive of activity. Paul Schullery has been watching wildlife here for 30 years and is one of the world's leading authorities on the park. As he guides us through this fresh, sunlit environment, wolves and grizzly bears mount extraordinary chase sequences in their quest for elk, and mountain lions gambol about without worry. Dramas occur in every season, for Yellowstone isn't just the world's first National Park - it's one of the great success stories in wildlife conservation.