Accipitridae
EOL Text
Fossils suggest that the first raptors appeared 30 to 50 million years ago. These early raptors looked similar to extant buzzards, though they are apparently not the predecessors of modern buzzards. Raptors probably became widespread before or during the Miocene.
Raptors have long played an important role in human history. Birds or prey have had religious or symbolic significance in many cultures, beginning with ancient civilizations and continuing with present-day societies. In the United States, bald eagles serve as the national emblem.
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Barcode of Life Data Systems (BOLD) Stats
Specimen Records: 862
Specimens with Sequences: 710
Specimens with Barcodes: 688
Species: 123
Species With Barcodes: 112
Public Records: 552
Public Species: 101
Public BINs: 95
Collection Sites: world map showing specimen collection locations for Accipitridae
The family Accipitridae encompasses many of the diurnal birds of prey, including the familiar hawks and eagles. It is one of the largest avian families, and the largest family in the order Falconiformes. The Howard and Moore Checklist of the Birds of the World recognizes 233 species in 67 genera in this family worldwide. Twenty-four of these species and 14 genera are native to North America. Many of the species in this family also include multiple subspecies. For example, up to 23 subspecies of the variable goshawk are recognized.
A great deal of diversity exists among the members of the Accipitridae. Members of this family span the globe, living in habitats as wide ranging as tundra, alpine meadows and rainforests. They eat fish, mammals, birds, bats, invertebrates, carrion and some fruit. They nest on cliffs, in trees or sometimes on the ground and lay between one and nine eggs. Physical size is also quite variable within this group, with wingspans ranging from 50 cm to 3 m.
- 2003. E Dickinson, ed. The Howard and Moore Complete Checklist of the Birds of the World. London: Christopher Helm.
- Kemp, A., I. Newton. 2003. Hawks, Eagles and Old World Vultures. Pp. 162-175 in C Perrins, ed. The New Encyclopedia of Birds. Oxford: Oxford University Press.
- Snyder, H. 2001. Hawks and Allies. Pp. 212-224 in C Elphick, J Dunning, D Sibley, eds. The Sibley Guide to Bird Life & Behavior. New York: Alfred A. Knopf, Inc.
- Thiollay, J. 1994. Family Accipitridae (hawks and eagles). Pp. 52-105 in J del Hoyo, A Elliott, J Sargatal, eds. Handbook of the Birds of the World. Vol. 2. New World Vultures to Guineafowl. Barcelona: Lynx Edicions.
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Though accurate worldwide population estimates for most accipitrid species are unavailable, data on well-known species suggests that overall raptor numbers are declining. Sixty of the 237 species in the Accipitridae are listed on The World Conservation Union’s IUCN Red List of Threatened Species. Nine of these are critically endangered, 4 are endangered, 23 are vulnerable, 23 are near threatened and 1 is data deficient.
Human persecution through shooting, trapping and poisoning has historically been the most significant source of raptor mortality. Though such activities are now illegal in most developed countries, and raptors are protected by legislation such as the Migratory Bird Treaty Act, shooting and poisoning continue to be a significant source of raptor mortality. Between the 1940's and 1960's, many accipitrids were poisoned by widely used organochlorine pesticides, such as DDT. These pesticides accumulated in the prey that raptors ingested, and caused population declines in many species. Use of these pesticides has declined sharply, though they continue to be used in many countries where raptors or their prey spend the winter. Populations of many species that were poisoned by organochlorine pesticides during the middle 1900’s are now experiencing dramatic increases.
Habitat loss is the largest threat facing raptor populations today. However, nest disturbance may also be a significant source of local reproductive failure and population decline in raptor species. Repeated disturbances at the nest force adults to spend more time on nest defense, and less time feeding and caring for their young. Disturbance can also cause nest abandonment in shy species, including bald eagles and white-tailed sea-eagles. The many potential sources of nest disturbance include forestry activities, roads, off-road vehicles, recreational activities such as cliff climbing and hang-gliding, low-flying aircraft and military exercises.
- IUCN, 2003. "2003 IUCN Red List of Threatened Species" (On-line). Accessed March 11, 2004 at http://www.redlist.org/.
- Threatened and Endangered Species System, 2003. "U.S. Listed Vertebrate Animal Species Report by Taoxonomic Group" (On-line). Accessed March 11, 2004 at http://ecos.fws.gov/tess_public/TESSWebpageVipListed?code=V&listings=0#B.
- U.S. Fish & Wildlife Service, 1997. "Birds Protected by the Migratory Bird Treaty Act" (On-line). Accessed March 11, 2004 at http://migratorybirds.fws.gov/intrnltr/mbta/mbtintro.html.
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Accipitrids are found world wide. They live on every continent except Antarctica, and on most oceanic islands. They inhabit every major habitat type except the northernmost arctic tundra and the driest deserts. The highest diversity of accipitrid species is found in tropical regions.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native ); oceanic islands (Native )
Other Geographic Terms: holarctic ; cosmopolitan
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Raptors are known to prey on game species, such as quails, partridges, pheasants and rabbits. They also occasionally take domesticated animals such as lambs and poultry.
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Accipitrids are diurnal birds of prey with broad wings, hooked beaks, strong legs and feet and sharp talons. All accipitrids have a cere, which is a waxy membrane that is often brightly colored, and covers the base of the upper mandible. They have large eyes that are shaded by a supraorbital ridge in most species, making the face appear fierce. Adult Accipitrids have wingspans ranging from 50 to 300 cm and total body lengths ranging from 25 to 150 cm. The body masses of Accipitrids range from 80 g to 12.5 kg.
An assortment of body shapes and plumage can be seen among Accipitrids. For example, tails can be square, rounded, wedge-shaped or even forked. Accipitrid physical characteristics reflect adaptations to their habitat, mode of foraging and prey. For example, forest dwelling species generally have short wings and long tails, a combination which affords them maneuverability. Species that live in open habitats and hunt by soaring generally have long, broad wings and short tails, which allow them to soar easily over long distances. Many of the soaring species also have "fingers", which are long outer primary feathers that reduce drag on the wings and allow the birds to soar at slow speeds without stalling.
Accipitrids are colored to blend in with their environment, and are usually brown, black or gray with some streaking or barring. Many have paler underparts than upperparts and barred underwing and tail feathers, a patterning that may make them less visible to prey. Several species of raptors show plumage polymorphism (light and dark morphs) or variation in plumage across their geographic range.
In most Accipitridae species, females are larger than males. This characteristic, called reversed sexual size dimorphism, is especially dramatic in bird-eating species. Though there is no consensus among scientists about why reversed sexual size dimorphism occurs, it is clearly more pronounced in species that hunt quick, agile prey. Some Accipitrids also show sexual dimorphism in plumage coloration. In species where this occurs, the male is usually more brightly colored than the female, and the female looks similar to the juveniles.
First-year accipitrid plumage is usually quite different from adult plumage, and very similar between species. Most juveniles have brown upperparts, sometimes mottled with light spots, and lighter underparts with brownish streaks. Juveniles also often have bigger (broader or longer) wing and tail feathers than adults, which may serve to make flying easier for the novice birds. After growing their first feathers, Accipitrids molt once per year. Many species develop adult plumage after the first year. In other species, including most eagles, the transformation from juvenile to adult plumage takes place over the course of several years, and the young bird passes through several sets of intermediate plumage.
Accipitrids share many traits with their falconid relatives, including strong beaks, feet and talons, and forward directed eyes. However, accipitrids are distinguished from falcons by their yellow, red or hazel, rather than brown eyes, nest building behavior (not exhibited in falcons), skeletal differences and forceful ejection of excreta.
Other Physical Features: endothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: female larger; sexes colored or patterned differently; male more colorful
- Sibley, C., J. Ahlquist. 1990. Phylogeny and Classification of Birds: A Study in Molecular Evolution. New Haven, Connecticut: Yale University Press.
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Humans have used raptors (both Accipitrids and falcons) for hunting and recreation in the form of falconry since as early as 2000 BC. Though this practice has largely died, it continues in some areas. Falconers in the United States use northern goshawks, Eurasian sparrowhawks and golden eagles to hunt prey including quails, partridges and pheasants and rabbits and hares.
Wild raptors include game animals and some domesticated animals, such as lambs and poultry among their prey. This led to a long period of widespread discrimination against raptors, beginning in the late 1700’s, and continuing to the 1970’s, when it generally ended in most developed countries. At the height of this period of destruction, roughly between 1860 and 1960, many governments gave rewards for the slaughter of millions of raptors.
Raptors can play an important role as bioindicators of habitat quality and pollution. In fact, they are already used in the tropics to monitor forest degradation. They may also help maintain the dynamics and diversity of ecosystems by lowering numbers of dominant prey, thereby allowing less common prey species to survive.
Eagle feathers are used by various indigenous societies in religious celebrations. Eagle feathers are used in arrows by some of the forest-dwelling tribes in South America. Body parts of many species are used in traditional medicine by healers in many parts of Asia, Africa, and the Caribbean. Raptors have been included in the cuisine of many regions, and are still eaten in Taiwan and the Philippines, as well as China.
Positive Impacts: pet trade ; food ; body parts are source of valuable material; ecotourism ; controls pest population
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