Peregrine Falcon

IDENTIFICATION: A medium-sized hawk with dark gray upperparts and a wedge-shaped patch extending below the eye that gives the falcon a helmeted look. Immature birds are dark brown above, with streaking below. In flight, this falcon has long, pointed wings. Length: 36-58 cm.; weight: 530-1,500 g.; wingspan: 91-112 cm.

VOICE: A raspy, "kek-kek-kek"; also wailing call notes. Audio (R. DeWitt).

HABITAT: In winter prefers edges of agricultural areas, marshes, wetlands, saltflats, and rocky islands; occasionally taller city buildings near parks frequented by Rock Pigeons.

HABITS: The Peregrine has been the prized hunting bird of falconers since the Middle Ages. It feeds on some small mammals and lizards, but mostly on birds, such as sandpipers, ducks, and city pigeons (Rock Pigeons). Its former name in Spanish and in English was "Duck Hawk," reflecting its taste for birds. The Peregrine spots prey either from a rock or tree perch, or by flying a low patrol pattern over flat terrain. It can reach speeds of more than 160 miles per hour as it dives in pursuit of prey, and can also climb rapidly to maneuver above a bird and strike from on high. The female is 15-20% heavier than the male, and thus focuses on larger prey (prey weights average 20-300 g. for males, versus 100-1,000 g. for females). On its North American breeding grounds, the Peregrine nests on a cliff ledge or high on a city skyscraper, or takes over a stick nest abandoned by other hawks or ravens. Many urban Peregrine nests have been featured on television news programs in North American cities. The male and female establish a strong pair bond and share incubation of their 3-4-egg clutch for 29-32 days. The male does most of the hunting during the incubation period. The young fledge at 35-42 days after hatching and are cared for by the parents during the first two months after departing the nest. Peregrines typically donÆt start breeding until two years of age. Peregrines have been fitted with radio transmitters and tracked by satellite from North America to winter grounds in Venezuela.

STATUS AND CONSERVATION: An uncommon winter visitor to Puerto Rico, the Peregrine Falcon had been on the federal endangered species list. After World War II, the use of the insecticide DDT, and other organochlorine chemicals, such as PCBs, caused Peregrines to lay thin-shelled eggs that broke during incubation. Rachel Carson helped alert the public to the hazards of persistent pesticides on wildlife in her 1962 book Silent Spring, a key work in the history of conservation. In 1970, the U.S. Fish & Wildlife Service listed the Peregrine Falcon as an endangered species. By 1975, the population reached a low of 324 nesting pairs in North America. Recovery efforts included a ban by the U.S. Environmental Protection Agency on the use of DDT, the protection of nest sites during the breeding season, captive breeding programs, and reintroduction efforts. Between 1974 and 1998, government and private raptor experts in North America reintroduced more than 6,000 falcons into the wild. Some reintroductions were made in urban areas after ornithologists discovered that Peregrines successfully adapted to nesting on skyscrapers, and hunted Rock Pigeons and European Starlings in cities. By 1999 there were at least 1,640 Peregrine Falcon breeding pairs in the United States and Canada, and the U.S. Fish & Wildlife Service removed the species from the endangered species list. As a result of this successful recovery effort, Peregrine sightings have become more common in Puerto Rico, including on the Cabo Rojo Chistmas Bird Count.

RANGE: This is one of the most widespread bird species in the world. It once bred throughout much of North America from subarctic boreal forests of Alaska and Canada, south to Mexico; as well as in the Andes south to Tierra del Fuego. In winter, northern Peregrine populations migrate widely (hence the name, "peregrine"), as far south as Central America and northeastern South America. Peregrines are uncommon in Puerto Rico, but have been seen in winter near fresh and salt water lagoons, on rocky islands, and even in city parks---all locations with flocks of medium-sized birds.

TAXONOMY: FALCONIFORMES; FALCONIDAE; Falconinae

Photo: J. Hornbuckle

Photo: J. Volpi*

References

Bent, A.C. 1938. Life histories of North American birds of prey, part 2. Smithsonian Instit. U.S. National Museum Bull. 170. (Reprinted by Dover Press, NY, 1961).

Bradley, M., R. Johnstone, G. Court, and T. Duncan. 1997. Influence of weather on breeding success of Peregrine Falcons in the Arctic. Auk 114:786-791.

Burger, J., and M. Gochfield. 1991. Lead, mercury and cadmium in feathers of tropical terns in Puerto Rico and Australia. Arch. Env. Contamination and Toxicology 21:311-315.

Craig, G. 1986. Peregrine Falcon. in Audubon Wildlife Report, 1986 (Eno, A. S. and R. L. Di Silvestro eds.) p.807-826. National Audubon Soc., NY.

del Hoyo, J., A. Elliott, and J. Sargatal, eds. 1994. Handbook of Birds of the World, Vol. 2, New World vultures to guineafowl. Lynx Edicions, Barcelona.

Ehrlich, P.R., D.S. Dobkin, and D. Wheye. 1988. The birderÆs handbook: a field guide to the natural history of North American birds. Simon and Schuster/ Fireside, NY.

Griffiths, C. S. 1999. Phylogeny of the Falconidae inferred from molecular and morphological data. Auk 116(1):116-130.

Johnsgard, P.A. 1990. Hawks, eagles, and falcons of North America: Biology and natural history. Smithsonian Institution Press. Washington, DC.

Raffaele, H.A. 1989. A guide to the birds of Puerto Rico and the Virgin Islands. Princeton.

Raffaele, H.A. 1989. Una guía a las aves de Puerto Rico y las Islas Vírgenes. Publishing Resources, Inc., Santurce, PR.

Raffaele, H.A., J.W. Wiley, O.H. Garrido, A.R. Keith, and J.I. Raffaele. 1998. Guide to the birds of the West Indies. Princeton.

Rivera-Milán, F.F. 1995. Distribution and abundance of raptors in Puerto Rico. Wilson Bull. 107(3):452-462.

Saliva, J.E. 1994. Vieques y su fauna: Vieques wildlife manual. U.S. Fish & Wildlife Service, Boquerón, PR.

Scholz, F. 1993. Birds of prey. Stackpole Books, Mechanicsburg, PA.

White, C. M., N. J. Clum, T. J. Cade, and W. G. Hunt. 2002. Peregrine Falcon (Falco peregrinus). In The Birds of North America, No. 660 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

http://endangered.fws.gov/i/b/sab22.html

http://www.frg.org/

http://www.macintech.net/

Raptors in general in Puerto Rico: http://netdial.caribe.net/~falconpr/

Peregrine Falcon, Spanish text

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Photo: G. Beaton