Birds of the World
This is my favorite of the Dorling Kindersley: Eyewitness Handbooks and I would venture to guess that it's probably the best bird handbook you can find. Hundreds of birds, from doves and swallows, to hawks and falcons and tropical birds are included with clear photos, a small map of where they can be found, an icon showing how large they are in comparison to the book, and other basic information about their habitat, migration, etc. Our family has used this guide extensively in identifying and learning more about the substantial variety of birds we find in our own backyard.