Accipitriformes is an order that includes most of the diurnal birds of prey: hawks, eagles, vultures, and many others, about 225 species in all. For a long time, the majority view has been to include them with the falcons in the Falconiformes, but many authorities have recognized a separate Accipitriformes. As of 2008, a recent DNA study indicated that falcons are not closely related to the Accipitriformes, being instead related to parrots and passerines.
Since then the split and the placement of the falcons next to the parrots in taxonomic order has been adopted by the American Ornithologists' Union's South American Classification Committee (SACC), its North American Classification Committee (NACC), and the International Ornithological Congress (IOC). The British Ornithologists' Union (BOU) already recognized the Accipitriformes, and has adopted the move of Falconiformes. The DNA-based proposal and the NACC and IOC classifications include the New World vultures in the Accipitriformes, while the SACC classifies the New World vultures as a separate order, the Cathartiformes. The latter view has been adopted here.
Accipitriformes are known from the Middle Eocene and typically have a sharply hooked beak with a soft cere housing the nostrils. Their wings are long and fairly broad, suitable for soaring flight, with the outer 4–6 primaries emarginated.
Accipitriformes have strong legs and feet with raptorial claws and an opposable hind claw. Almost all Accipitriformes are carnivorous, hunting by sight during the day or at twilight. They are exceptionally long-lived, and most have low reproductiverates.
The young have a long, very fast-growing fledgling stage, followed by 3–8 weeks of nest care after first flight, and 1 to 3 years as sexually immature adults. The sexes have conspicuously different sizes and sometimes a female is more than twice as heavy as her mate. This sexual dimorphism is sometimes most extreme in specialized bird-eaters, such as the Accipiterhawks, and borders on non-existent among the vultures. Monogamy is the general rule, although an alternative mate is often selected if one dies.
- Accipitridae (buzzards, eagles, harriers, hawks, kites, Old World vultures)
- Pandionidae (Osprey)
- Sagittariidae (Secretarybird)