Parrots of the World covers all 356 species of parrots, including extinct species such as the Carolina Parakeet. The guide groups species by geography rather than taxonomy, to make it easier to find species in the field. Each species is represented with the high quality painted illustrations I have come to expect from Princeton's field guides. Illustrations depict each species's major forms, as well as the uppersides and undersides of their wings and tails. The top and bottom views appear more like study skins than flying birds, but they achieve the same goal as a depiction of a flying bird would.
Facing each color plate is a page with text for each depicted species. The accounts include a range map, identification points, and notes on the bird's distribution and conservation status. Each account also names a handful of places where a species is most likely to be found. The suggested locations are usually national parks or other protected reserves, or in some cases lodges that cater to birders.
Why might a North American birder want a field guide on parrots when the only native parrot species in the U.S. or Canada is extinct? First, parrots are beautiful and intriguing species. Some are highly intelligent, and many are threatened by habitat loss or capture. Of the 356 species, 123 are listed as threatened or endangered by BirdLife International. This makes parrots one of the most threatened groups of birds. This alone makes it worth learning more about parrots.
Second, exotic parrots are establishing themselves in American cities by escapes or releases of imported birds. Monk Parakeets are on the state lists for New York, Illinois (pdf), and more recently New Jersey (pdf); they have been documented in other states as well. California and Florida have small populations of numerous parrots. Escaped pet parrots like Budgerigars can turn up almost anywhere. Virtually any species brought into the country can escape and not all of them are depicted in standard field guides. (The Sibley Guide to Birds and The Crossley ID Guide both have extensive sections on the most common feral parrots.) Since Parrots of the World covers species from every continent, it is a useful reference for checking the identity of an unknown parrot. I think it will prove especially helpful to urban birders who encounter escaped or feral parrots on a regular basis.