Book excerpt: "Perhaps beginning near the end of the Pleistocene, Peregrines began to acquire a vast cosmopolitan distribution, and set the stage for fascinating structural, behavioral, and population distinctions related to where they lived. Those divergences were driven by the various demands of landscapes as different as one can find on earth, including Greenland tundra, South Pacific islands, Utah arid scrublands, the cold wind-swept Aleutians, and warm, moist Indonesian forests. Modern Peregrines reveal that geographic isolation may befall even a creature renowned for great speed and mobility. Peregrine Falcons of the World brings together the lifetime experiences of the authors with this splendid falcon in the field and in museums, hundreds of personal accounts by Peregrine observers worldwide, a vast literature on this falcon which is surely among the best-studied birds, scores of superb photographic images so generously supplied, and the matchless art of Andrew Ellis. The goal is to provide a feel for how Peregrines have responded to their varied world, and to earmark the many gaps in what we know. Oddly, Peregrines have not colonized many places, where by any reckoning, they should be. In recent times, roughly twenty subspecies of Peregrines were described. The historical reasons for these designations, and our current analyses are provided here. Some populations are very distinct in form and color, but sometimes they geographically overlap and intergrades appear. Each subspecies account also describes distribution, hunting and nesting habitats, migration and wintering ranges, estimated population sizes, and conservation aspects. In the end, present day Peregrines appear in at least a score of populations experiencing different degrees of isolation and enjoying different rates of divergence. The challenge of understanding their relationships is sometimes made greater by almost complete lack of information or specimens from vast regions where neighboring subspecies apparently come together because no obvious barrier exists. But the Peregrine Falcon will never lack for serious aficionados. Field people around the world add to the growing literature almost weekly so that someday a more complete appreciation is inevitable." --Publisher's description.