The most comprehensive field guide available to the Rocky Mountain region--a portable, essential companion for visitors and residents alike--from the go-to reference source for over 18 million nature lovers. This compact volume contains: An easy-to-use field guide for identifying 1,000 of the state's wildflowers, trees, mushrooms, mosses, fishes, amphibians, reptiles, birds, butterflies, mammals, and much more; A complete overview of the Rocky Mountain region's natural history, covering geology, wildlife habitats, ecology, fossils, rocks and minerals, clouds and weather patterns, and the night sky; An extensive sampling of the area's best parks, preserves, mountains, forests, and wildlife sanctuaries, with detailed descriptions and visitor information for 50 sites and notes on dozens of others. The guide is packed with visual information -- the 1,500 full-color images include more than 1,300 photographs, 11 maps, and 16 night-sky charts, as well as more than 100 drawings explaining everything from geological processes to the basic features of different plants and animals.   For everyone who lives or spends time in Colorado, Idaho, Montana, or Wyoming, there can be no finer guide to the area's natural surroundings than the National Audubon Society Field Guide to the Rocky Mountain States.