Colorado is a unique birding spot, with both its Rocky Mountain terrain and its flat highlands. Discover: the White Ptarmigan, a grouse-like bird in the high tundra, which molts an amazing 3 times to match its environment (most birds only molt once a year to replace worn feathers); the Golden Eagle soaring above the buttes in Pawnee National Grasslands; the American Dipper, known for its characteristic bobbing movement, along mid-elevation hiking trails; the Eared Grebe, with its spray of golden feathers or "ears" fanning out behind its eyes, swimming in a high-altitude lake; and the chestnut-coloured Longspurs displaying its courtship dance, or song flight, above rolling meadows. "National Geographic Field Guide to Birds: Colorado" is the 6th set in the series of pocket-size bird field guides. Each guide is 272 pages and features about 175 birds. The book's trim size fits in a backpack or pocket for easy access.