Peregrines grow 38 to 50 cm (15 to 20 in) in length, with females typically about one-third larger than males. The black head has a prominent “mustache” mark on the side of the face.
Peregrines hunt live birds, including chickadees, goldfinches, pigeons, ducks, and gulls. They dive from great heights to strike prey with their talons (claws). If this impact does not kill the prey, the peregrine bites the neck of its victim to ensure death.
Peregrines typically mate for life. Because of the size difference between a male and a female, a mated pair generally hunts different prey species. Peregrines make their nests on high cliff ledges. Many peregrines have adapted to urban areas by nesting on skyscrapers and other tall structures. Females typically lay two to four eggs a year, which they incubate while the male hunts food for them both. The chicks hatch after about 35 days, and then both parents hunt for food for the young. Chicks leave the nest four to five weeks after hatching.
Peregrine falcons once ranged throughout North America, from as far north as Alaska to as far south as Mexico. In the 1940s, populations began to decline, primarily due to the widespread use of the pesticide DDT. This chemical caused peregrines and many other birds to lay thin-shelled eggs that broke easily. The United States Fish and Wildlife Service (FWS) listed the peregrine as an endangered species in 1970. By 1975 the peregrine population in North America had dropped to only 324 nesting pairs.
DDT was banned in the United States and Canada in 1973. Researchers, meanwhile, undertook a massive effort to help the peregrine recover. Groups such as the Idaho-based Peregrine Fund, the University of Minnesota’s Raptor Center, and the University of California at Santa Cruz’s Predatory Bird Research Center bred peregrines and released them into the wild. These captive-breeding programs, in conjunction with nationwide efforts to avoid disturbing peregrine nests, slowly brought the birds back from the edge of extinction. By 1998 the number of nesting pairs in North America had grown to 1,650.
In 1999 the FWS removed the peregrine from the endangered species list. The FWS plans to monitor the peregrine population to ensure that it remains stable. If necessary, the birds could be returned to the endangered species list. The birds are also protected by the Migratory Bird Treaty Act of 1918, which forbids killing peregrines or possessing the birds or their egg. (Encarta Encyclopedia)