Sibley, David A.The Sibley Guide to Birds. Knopf, 2000. Detailed National Audubon Society guide; more of a desk reference than a pocket guide.
Birds
Del Hoyo, Joseph, and others, eds. Handbook of the Birds of the World. Lynx, 1992-1997. Multi-volume work on bird families, with photographs of each species.
Attenborough, David.The Life of Birds. Princeton University Press, 1998. Richly illustrated accompaniment to a 10-part series on public television.
Forshaw, Joseph, and David Kirshner, eds.Encyclopedia of Birds. Academic Press, 1998. A beautifully illustrated textual exploration by some of the world's leading ornithologists.
Fuller, Errol.Extinct Birds. Cornell University Press, 2001. Rich historical research reveals 75 bird species that have become extinct since 1600.