Compact and comprehensive, this guide features 715 bird species, plus regional populations, found west of the Rocky Mountains. Entries include stunningly accurate illustrations--more than 5,046 in total--with descriptive captions pointing out the most important field marks. Each entry has been updated to include the most current information concerning frequency, nesting, behavior, food and feeding, voice description, and key identification features. Here too are more than 652 updated maps drawn from information contributed by 110 regional experts across the continent, showing winter, summer, year-round, migration, and rare ranges. The new design reflects the layout of The Sibley Guide to Birds, Second Edition. All species accounts are now presented in columns, rather than stacked, allowing for better comparison and more illustrations of each species. Current taxonomic order and up-to-date common names. All maps revised to reflect the most current range information. More species and rarities included.