All 39 of North American hawks and other diurnal raptors, including eagles, falcons, and vultures
Color paintings and photographs of each species in various color morphs, plumages, and postures
Detailed descriptions of each species, including field marks, plumages (usual and unusual), flight modes, characteristic behaviors, voice, status and distribution, similar species, subspecies, measurements, and even the origin of the name
Range maps showing where each species can be found
This small, compact Peterson field guide has a wealth of identification information for North American raptors. Besides the typical Peterson "arrow" technique for noting key identification marks, it also includes many flight photographs in the end papers of the guide.
I have the first edition (1987) which is okay, but not current enough. It also has black and white photos that aren't very helpful. It's the only hawk-specific guide I own, though, so I do use it sometimes. I'm just not much of a hawk watcher, so I haven't bothered to get a better hawk guide.