Every birder has a field guide, but every birder ought to have two.
Expert birders usually recommend a field guide with paintings of the birds rather than photos because a good artist can emphasize features of a species that make it easier to identify from several similar species. Roger Tory Peterson was such an artist, and his series of guides has become the most widely used for field identification. But we human's can't seem to escape the desire to see the real thing, and several guides employing photographs are on the market. The Audubon series has long been popular, but suffers from small and sometimes difficult to use photos. A few years ago, Don and Lillian Stokes, a Massachusetts couple who has written two dozen wildlife books, published Stokes Field Guide to Birds, also using photographs.