Birds of prey or predatory birds, also known as raptors, are hypercarnivorous species of bird that actively hunt and feed on other vertebrates, mainly mammals, reptiles, and smaller birds. In addition to speed and strength, these predators have keen eyesight for detecting prey from a distance or during flight, strong feet with sharp talons for grasping or killing prey, and powerful, curved beaks for tearing flesh. Although predatory birds primarily hunt live prey, many species—such as fish eagles, vultures, and condors—also scavenge and eat carrion.
Although the term "bird of prey" could theoretically be taken to include all birds that actively hunt and eat other animals, ornithologists typically use the narrower definition followed in this page, excluding many piscivorous predators such as storks, cranes, herons, gulls, skuas, penguins, and kingfishers, as well as many primarily insectivorous birds such as nightjars, frogmouths, and some passerines (e.g. shrikes); omnivorous passerine birds such as crows and ravens; and opportunistic predators from predominantly frugivorous or herbivorous ratites such as cassowaries and rheas. Some extinct predatory telluravian birds had talons similar to those of modern birds of prey, including mousebird relatives (Sandcoleidae), and Messelasturidae indicating possible common descent. Some Enantiornithes also had such talons, indicating possible convergent evolution, as enanthiornithines are not considered to be true modern birds.
Common names The term raptor is derived from the Latin word , meaning "to seize or take by force". The common names for various birds of prey are based on structure, but many of the traditional names do not reflect the evolutionary relationships between the groups.
Eagles tend to be large, powerful birds with long, broad wings and massive feet. Booted eagles have legs and feet feathered to the toes and build very large stick nests. Falcons and kestrels are medium-size birds of prey with long pointed wings, and many are particularly swift flyers. They belong to the family Falconidae, only distantly related to the Accipitriformes below. Caracaras are a distinct subgroup of the Falconidae unique to the New World, and most common in the Neotropics – their broad wings, naked faces and appetites of a generalist suggest some level of convergence with either Buteo or the vulturine birds, or both. True hawks are medium-sized birds of prey that usually belong to the genus Accipiter (see below). They are mainly woodland birds that hunt by sudden dashes from a concealed perch. They usually have long tails for tight steering. Buzzards are medium-large raptors with robust bodies and broad wings, or, alternatively, any bird of the genus Buteo, also commonly known as "hawks" in North America, while "buzzard" is colloquially used for vultures. Harriers are large, slender hawk-like birds with long tails and long thin legs. Most use a combination of keen eyesight and hearing to hunt small vertebrates, gliding on their long broad wings and circling low over grasslands and marshes. Kites have long wings and relatively weak legs. They spend much of their time soaring. They will take live vertebrate prey, but mostly feed on insects or even carrion. The osprey, a single species found worldwide that specializes in catching fish and builds large stick nests. Owls are variable-sized, typically night-specialized hunting birds. They fly almost silently due to their special feather structure that reduces turbulence. They have particularly acute hearing and nocturnal eyesight. The secretary bird is a single species with a large body and long, stilted legs endemic to the open grasslands of Sub-Saharan Africa. Vultures are scavengers and carrion-eating raptors of two distinct biological families: the Old World vultures (Accipitridae), which occurs only in the Eastern Hemisphere; and the New World vultures, Cathartidae, which occurs only in the Western Hemisphere. Members of both groups have heads either partly or fully devoid of feathers.
Many of these group names originally referred to particular species encountered in Britain. As English‑speaking people travelled further, the familiar names were applied to new birds with similar characteristics. Names that have generalised in this way include: kite Milvus milvus; sparrowhawk or sparhawk Accipiter nisus; goshawk Accipiter gentilis; kestrel Falco tinnunculus; hobby Falco subbuteo; harrier (from "hen‑harrier") Circus cyaneus; and buzzard Buteo buteo.
Some names have not generalised and refer to single species or groups of closely related subspecies, such as the merlin, Falco columbarius.
Systematics Historical classifications The taxonomy of Carl Linnaeus grouped birds (class Aves) into orders, genera, and species, with no formal ranks between genus and order. He placed all birds of prey into a single order, Accipitres, subdividing this into four genera: Vultur (vultures), Falco (eagles, hawks, falcons, etc.), Strix (owls), and Lanius (shrikes). This approach was followed by subsequent authors such as Gmelin, Latham and Turton.
Louis Pierre Vieillot used additional ranks: order, tribe, family, genus, species. Birds of prey (order Accipitres) were divided into diurnal and nocturnal tribes; the owls remained monogeneric (family Ægolii, genus Strix), whilst the diurnal raptors were divided into three families: Vulturini, Gypaëti, and Accipitrini. Thus Vieillot's families were similar to the Linnaean genera, with the difference that shrikes were no longer included amongst the birds of prey. In addition to the original Vultur and Falco (now reduced in scope), Vieillot adopted four genera from Savigny: Phene, Haliæetus, Pandion, and Elanus. He also introduced five new genera of vultures (Gypagus, Catharista, Daptrius, Ibycter, Polyborus) and eleven new genera of accipitrines (Aquila, Circaëtus, Circus, Buteo, Milvus, Ictinia, Physeta, Harpia, Spizaëtus, Asturina, Sparvius).
Falconimorphae is a deprecated superorder within Raptores, formerly composed of the orders Falconiformes and Strigiformes. The clade was invalidated after 2012. Falconiformes is now placed in Eufalconimorphae, while Strigiformes is placed in Afroaves.
Modern systematics
The order Accipitriformes is believed to have originated about 44 million years ago, when the lineage leading to modern accipitrids diverged from that of the secretarybird (Sagittarius serpentarius) and the accipitrid species. The phylogeny of Accipitriformes is complex and difficult to unravel. Widespread paraphylies were observed in many phylogenetic studies. More recent and detailed studies show similar results. However, according to the findings of a 2014 study, the sister relationship between larger clades of Accipitriformes was well supported (e.g. relationship of Harpagus kites to buzzards and sea eagles and these latter two with Accipiter hawks are sister taxa of the clade containing Aquilinae and Harpiinae).
The diurnal birds of prey are formally classified into six families of two different orders (Accipitriformes and Falconiformes). Accipitridae: hawks, eagles, buzzards, harriers, kites, and Old World vultures Pandionidae: the osprey Sagittariidae: the secretarybird Falconidae: falcons, caracaras, and forest falcons Cathartidae: New World vultures, including condors
These families were traditionally grouped together in a single order Falconiformes but are now split into two orders, the Falconiformes and Accipitriformes. The Cathartidae are sometimes placed in a separate order Cathartiformes. Formerly, they were sometimes placed in the order Ciconiiformes.
The secretary bird and/or osprey are sometimes listed as subfamilies of Acciptridae: Sagittariinae and Pandioninae, respectively.
Australia's letter-winged kite is a member of the family Accipitridae, although it is a nocturnal bird.
The nocturnal birds of prey—the owls—are classified separately as members of two extant families of the order Strigiformes: Strigidae: "typical owls" Tytonidae: barn and bay owls
Phylogeny Below is a simplified phylogeny of Telluraves which is the clade where the birds of prey belong to along with passerines and several near-passerine lineages. The orders in bold text are birds of prey orders; this is to show the paraphyly of the group as well as their relationships to other birds.
A recent phylogenomic study from Wu et al. (2024) has found an alternative phylogeny for the placement of the birds of prey. Their analysis has found support in a clade consisting of the Strigiformes and Accipitriformes in new clade Hieraves. Hieraves was also recovered to be the sister clade to Australaves (which it includes the Cariamiformes and Falconiformes along with Psittacopasserae). Below is their phylogeny from the study.
Possible inclusion of Cariamiformes Cariamiformes is an order of telluravian birds consisting of the living seriemas and extinct terror birds. Jarvis et al. 2014 suggested including them in the category of birds of prey, and McClure et al. 2019 considered seriemas to be birds of prey. The Peregrine Fund also considers seriemas to be birds of prey. Like most birds of prey, seriemas and terror birds prey on vertebrates.
However, seriemas were not traditionally considered birds of prey, and they are still not considered birds of prey in general parlance. They were traditionally classified in the order Gruiformes, but later research has reclassified them into Cariamiformes.
The bodies of seriemas are also shaped somewhat differently from birds of prey. Their legs and necks are significantly longer than those of typical raptors, although the secretarybirds (traditionally considered raptors) also have comparably long legs. The beaks of seriemas are hooked (as in raptors), but are longer than those of typical raptors.
Migration Migratory behaviour evolved multiple times within accipitrid raptors.
The earliest event occurred nearly 14 to 12 million years ago. This result seems to be one of the oldest dates published so far in the case of birds of prey. For example, a previous reconstruction of migratory behaviour in one Buteo clade with a result of the origin of migration around 5 million years ago was also supported by that study.
Migratory species of raptors may have had a southern origin because it seems that all of the major lineages within Accipitridae had an origin in one of the biogeographic realms of the Southern Hemisphere. The appearance of migratory behaviour occurred in the tropics parallel with the range expansion of migratory species to temperate habitats. Similar results of southern origin in other taxonomic groups can be found in the literature.
Distribution and biogeographic history highly determine the origin of migration in birds of prey. Based on some comparative analyses, diet breadth also has an effect on the evolution of migratory behaviour in this group, but its relevance needs further investigation. The evolution of migration in animals seems to be a complex and difficult topic with many unanswered questions.