The Yellowstone region is one of the planet's largest, nearly intact temperate zone ecosystems. The area surrounding Yellowstone is also the fastest-growing population center in the western United States, doubling its population since 1970. Red squirrels, pygmy rabbits, and pelicans-are all proverbial "canaries in the coal mine." By understanding these creatures better and their habitats, scientists and the citizenry of the ecosystem can find solutions to cope with the changing environment.