Roger Tory Peterson's unique identification system explains exactly what features to look for to tell one species from another. In each Peterson Field Guide, an author with expertise in the subject and an experienced artist work closely with the editors to ensure that both text and illustrations are accurate. This edition includes 100 color photographs of tracks and signs, more than 1,000 line drawings, and nomenclature for all the mammals of North America. The text includes descriptions of habits, habitats, tracks, signs, and ranges, and is filled with wonderful natural history stories. Olaus J. Murie, one of America's leading mammalogists, has completed fieldwork throughout the United States and Canada, from Labrador to the Aleutian Islands, with special concentration in the Northwest.