One of the most widely distributed of warm-blooded terrestrial vertebrates, the Peregrine Falcon occurs from the tundra to the Tropics, from wetlands to deserts, from maritime islands to continental forests, and from featureless plains to mountain crags-it is absent as a breeder only from the Amazon Basin, the Sahara Desert, most of the steppes of central and eastern Asia, and Antarctica. This depth and breadth of habitat reflects a prodigiously catholic diet that includes many hundreds of species of birds, some bats, and a few rodents, and yet a commonality of ways in which Peregrines pursue them. The presence of this species in the pristine landscape has no doubt influenced the morphological and behavioral evolution of countless avian species. Even so, some populations of Peregrines are food specialists; in the Pacific Northwest, for example, enormous numbers of a few marine bird species support one of the densest-known Peregrine populations.
The often-held image of the Peregrine as a symbol of wilderness diminishes when one sees this falcon breeding on metropolitan bridges and urban skyscrapers or watches tundra migrants on their neotropical nonbreeding grounds speeding along traffic-jammed boulevards at streetlight height in Rio de Janeiro, Brazil, or Buenos Aires, Argentina, chasing bats at sunset. Indeed, a Peregrine is always worth watching; humankind has long admired this species as nature's perfect aerodynamic performer and as a strikingly beautiful bird.
Few other North American species held as high a scientific and public profile in the twentieth century. Among the most studied of wild avian species, with a bibliography exceeding 2,000 primary scientific titles, the Peregrine was a cause célèbre of the environmental awakening of the 1970s. Ironically, its popularity increased with its disappearance as a breeding species from most of eastern North America and parts of Europe and its marked reduction over most of the rest of North America, Europe, and (probably) northern Asia. Although it was thought in many circles to be a globally declining and endangered species, this was never so. The Peregrine was, however, greatly harmed, along with other birds of prey and some marine birds, by the widespread use of persistent chemicals that lowered reproduction and survival rates. By 1970, the Peregrine was federally protected in the United States, and the chemical culprits were virtually banned in North America by 1972. Peregrines have since made a strong recovery, aided in part by restorative management.
The name Peregrine means "wanderer," and northern-nesting Peregrines are among North America's long-distance migratory species, some moving 25,000 kilometers annually. It is difficult to characterize the resident status of the Peregrine as a species. While most spend but a few months over the northern third of their North American breeding range, some populations remain sedentary; for example, mated pairs can be seen sitting together on their snow-covered breeding ledges in January in the Aleutian Islands.
Although most North American Peregrines used to nest on cliffs, their establishment as urban denizens over the past 2 decades ( Frank 1994 , Cade et al. 1996b ) has been dramatic and highly publicized in the popular press. Increasingly, they use other unconventional nest sites such as old Common Raven (Corvus corax) nests on electric pylons, Osprey (Pandion haliaetus) and cormorant (Phalacrocorax spp.) nests on channel buoys, abandoned Bald Eagle (Haliaeetus leucocephalus) nests along the Pacific Coast, an emergent dead tree snag in California, and special towers in salt marshes. Recently they have even extended their nesting range to such an unexpected location as Cuba ( Regalado and Cables 2000 ).