Peterson Field Guide to Western Birds by Roger Tory Peterson (Series Editor), Virginia Marie Peterson (Editor). A Field Guide to Western Birds: A complete field Guide to Field Marks of All Species Found in North America West of the 100th Meridian and North of Mexico (Paperback) This is one of the all-time best selling field guides featuring the unique Peterson Identification System. This book covers all birds of North America west of the 100th meridian and north of Mexico. Each bird is shown in full color and described in detail. Summer and winter ranges, breeding grounds, and other special range information are shown on easy-to-read range maps.