- Colorado Atlas & Gazetteer
Publisher: DeLorme (October 2002)
- The Roads of Colorado
Publisher: Shearer (September 1996)
These are the two commercial atlases most often used by birders in Colorado. Either will suffice to get you around the state. Older versions of DeLorme did not provide as much information on public/private land boundaries as Roads of Colorado, but newer versions are comparable. The main difference now is that Roads of Colorado maps the whole state at the same scale, while Delorme "skimps" on the Eastern Plains, "zooming out" to fit them on fewer pages.
- A Birder's Guide to Colorado, Revised 4th Edition
Harold R. Holt
Publisher: American Birding Association (February 1997)
This is the statewide standard in this genre. Keep an eye out for the completely revised and expanded 5th Edition!
- Birding Rocky Mountain National Park
Publisher: Johnson Books (March 2002)
- Colorado Birds: A Reference to Their Distribution and Habitat
Robert Andrews & Robert Righter
Publisher: Denver Museum of Natural History (1992)
Affectionately known as "Bob & Bob", this book is the standard reference on bird distribution in Colorado.
- Colorado Breeding Birds Atlas
Hugh E. Kingery, editor; illustrated by Radeaux
Publisher: Colorado Division of Wildlife (1998)
- Birds of Western Colorado Plateau and Mesa Country
Robert Righter, Rich Levad, Coen Dexter, Kim Potter; illustrated by Don Radovich
Publisher: Grand Valley Audubon Society (2004)
This excellent reference covers an area slightly larger than the western tier of counties in Colorado.
- Bird Songs of the Rocky Mountain States and Provinces
Robert Righter & Geoffrey A. Keller
Publisher: Cornell Laboratory of Ornithology (June 1999)
- Checklist of the Birds of Colorado
Publisher: Colorado Field Ornithologists (2002)