This new regional field guide offers in-depth coverage of every North American bird officially recorded west of the Rocky Mountains. The guide includes illustrated accounts of the different plumages and life stages for an estimated 750 western species, along with 600 (est) new range maps. In addition, there are illustrated accounts for more than 100 Casual and Accidental birds, along with an appendix listing records for 55 western rarities.National Geographic has packed this guide with a number of new and unique features that set it apart from the existing, a Visual Index, printed on the inside front and back covers, which lets readers access the content visually. This feature will be especially helpful to the beginning-and-intermediate birding audience. It also features: extensively annotated art, which highlights the birds' key physical features, facilitating identification; identification tip boxes, which help with the most challenging identifications; thumbtabs, to help readers find information fast; 600 (est) new range maps and 70 new art figures; and, durable cover and quick-reference flaps that double as placemarkers.