Bird pictures help you identify the birds you are seeing, and a guide to bird watching (birding) can hardly be done without detailed illustrations. Many fine bird guides now offer quality illustrations.
The book The Sibley Guide to Birds made a huge impression on the birding community when it came out in 2000. With its 6000 detailed illustrations of birds in various attitudes and in flight, it assists identification like no other such book. David Sibley has now produced The Sibley Guide to Bird Life and Behavior and is coming out with Sibley's Birding Basics, due in October 2002.
Other guides with copious bird pictures include the pair of Peterson guides, A Field Guide to the Birds of Eastern and Central North and A Field Guide to Western Birds, as well as the Smithsonian's Birds of North America, a large book illustrating over 900 species. Bird Pictures are beautiful, can help us identify the birds we are seeing, and appreciate them all the more.