FALCONIFORM

(order Falconiformes), any of the group of swift, graceful birds known for their predatory, or raptorial, skill. Included are eagles, condors, buzzards, kites, caracaras, ospreys, harriers, accipiters, vultures, secretary birds, falcons, hawks, and bateleurs. More than any other group of birds, the diurnal falconiforms have long been of human interest. They are often large, conspicuous birds that attract attention from smaller birds. Falconiforms compete with humans for food by occasionally preying on domestic stock (though on a small scale). More significantly, they feed upon pests of human food supplies. Because of their raptorial skill, a few falcons and hawks are used for falconry, mainly for sport, much less importantly to obtain food. any member of an order (Falconiformes) of swift, graceful birds known for their predatory or raptorial skill; the group includes eagles, condors, buzzards, kites, caracaras, ospreys, harriers, accipiters, vultures, secretary birds, falcons, hawks, bateleurs, and buteos. On occasion, falconiforms prey on small domestic stock, but mostly they feed on smaller wild birds, rodents and other small mammals, or carrion. A few falcons and hawks are used in the sport of falconry (q.v.). Certain general features are common to all members of this order. Falconiforms are diurnal creatures. Most do not migrate. Although most falconiforms are large, they vary in size from tiny falconets weighing as little as 35 grams (1.2 ounces) to huge vultures and eagles with weights up to 14 kilograms (31 pounds). Females, generally the better hunters in most species, are 1020 percent larger than the males. The beak is always hooked and is used to tear flesh from prey. The unusually strong feet equipped with long talons are used for killing prey. Sight and hearing are keen, but smell is usually weak. Falconiforms are found throughout the world (except Antarctica), but are commonest in warm, open country. While food supply exerts some influence on falconiform populations, their density of distribution seems to be limited by territorial behaviour as well. Falconiforms seem to require a large area for each breeding pair. Large falconiforms are among the longest-lived birds. Ospreys and buteos live an average of 8 to 10 years, but life spans of more than 20 years have been recorded. Smaller falcons and accipiters average a life span of approximately 3 years, but some may reach 10 or 12 years. The larger raptors, such as eagles, can live 1824 years in the wild. All of these species live much longer in captivity. The falconiform life cycle consists of four stages, the length of which is directly proportional to the size of the bird. The fledging period, from hatching to first flight, varies from 23 days in small accipiters to 150 days in large condors. The post-fledging period, in which the young stay near the nest and food is brought by the parents, varies from one month to almost a year. The period as a juvenile, when the bird is independent but sexually immature, ranges from about nine months in small species (kestrels and sparrow hawks) to some four years in large eagles, and up to seven years in condors. The sexually mature birds mate, nest, and reproduce. Falconiforms are daylight hunters. When not hunting, falconiforms rest on perches or soar. As a rule, vultures and eagles seen soaring very high up are not hunting. Toward evening a falconiform may return to a regular roosting site. All falconiforms fly well. The large species have long and relatively broad wings particularly adapted for soaring flight, and accipiters, swift falcons, and the secretary bird can soar well although these birds rely more on flapping flight. Falcons, especially those that kill other birds, have bullet-shaped bodies and long, pointed wings that facilitate high diving speed to overtake and attack their prey in midair. Many falconiforms pair for life; others, mostly migrant species, may pair anew each year. The breeding pattern in falconiforms follows that of other bird groupsnuptial display, nest building, incubation, fledging period, and post-fledging period. Breeding time varies from about 3 months in small species to 15 months in the largest birds. Most species perform several types of nuptial displays. Perhaps the most spectacular (though rare) nuptial display is that of some eagles and kites that may lock feet and tumble in a cartwheel toward the ground. Most species build nests in trees, ledges, cliffs, or, rarely, on the ground. Many species lay only one egg; few lay more than four. The eggs hatch in the order in which they were laid. Feathers erupt during the fledging period. At about this time most young learn to tear up the prey brought to them by their parents. They make their first flights unaided by parental coaching. Most falconiforms are directly beneficial to human beings since they feed on pests or carrion. However, many of these bird species are in danger. The spread of agriculture has destroyed many of their habitats, such as forests. DDT and other toxic chemicals used in farming have affected the birds' ability to reproduce. Overcollecting for zoos and museums and for the sport of falconry also continues to have an adverse effect on some species. Falconiforms have no obvious evolutionary links with other birds. Such evidence as there is suggests that they diverged from their ancestral types 20 million or more years ago and that their relationships with other bird groups have since become obscured. Additional reading Leslie Brown and Dean Amadon, Eagles, Hawks, and Falcons of the World, 2 vol. (1968, reprinted in 1 vol., 1989), contains extensive information on the natural history of every species of the falconiforms. Mary Louise Grossman and John Hamlet, Birds of Prey of the World (1964, reprinted 1988), a heavily illustrated work dealing with both falconiforms and owls, provides range maps for each species, good photographs, and a reading list by geographic region and by genus. H. Kirke Swann, A Monograph of the Birds of Prey (Order Accipitres), 2 vol. (193045), is a classic work on the biology of the falconiforms of the world, with many fine colour plates. Ian Newton (ed.), Birds of Prey (1990), is a popular account of diurnal raptors. John J. Craighead and Frank C. Craighead, Jr., Hawks, Owls, and Wildlife (1956, reprinted 1969), is a detailed study of the ecology of raptorial birds and their impact on prey populations. Leslie Brown, African Birds of Prey (1970), offers an ecological study of falconiforms and owls on the African continent. Paul A. Johnsgard, Hawks, Eagles & Falcons of North America (1990), focuses on biology and natural history. Particular species are dealt with in G. Ronald Austing, The World of the Red-Tailed Hawk (1964), a photographic essay on the daily life of this common North American buteo; Leslie Brown, Eagles of the World (1977), an account of the biology of these impressive birds, written for a general audience; Philip Brown and George Waterston, The Return of the Osprey (1962), a detailed account of the natural history of the osprey; Alan F. Poole, Ospreys: A Natural and Unnatural History (1989), a world survey of their biology, with case studies of populations in New England and Scotland; Tom J. Cade, The Falcons of the World (1982); and Tom J. Cade et al. (eds.), Peregrine Falcon PopulationsTheir Management and Recovery (1988). Leslie Hilton Brown The Editors of the Encyclopdia Britannica