The Sibley Guide to Birds Comprehensive with lots of great illustrations.
The Sibley Field Guide to Birds of Western North America Great field reference.
Field Guide to the Birds of North America New standard in photo guides.
Birding in the American West: A Handbook (Comstock Books) Much more info than in your field guide.
Hummingbirds of North America: Attracting, Feeding, and Photographing
Hawks in Flight: The Flight Identification of North American Migrant Raptors Extremely useful for those hard to ID high-flying raptors.
A Field Guide to Western Birds: A Completely New Guide to Field Marks of All Species Found in North America West of the 100th Meridian and North of Mexico (Peterson Field Guide)
Birding Hot Spots of Central New Mexico (W. L. Moody Jr. Natural History Series Book 42) The best birding spots chosen by the best birders.