Now comes a new portable guide from David Sibley that every birder will want to carry into the field. Compact and comprehensive, this new guide features 703 bird species plus regional populations found west of the Rocky Mountains. Accounts include stunningly accurate illustrationsmore than 4,600 in totalwith descriptive caption text pointing out the most important field marks. Each entry contains new text concerning frequency, nesting, behavior, food and feeding, voice description, and key identification features.