Falcons () are birds of prey in the genus Falco, which includes about 40 species. Some small species of falcons with long, narrow wings are called hobbies, and some that hover while hunting are called kestrels. Falcons are widely distributed on all continents of the world except Antarctica, though closely related raptors did occur there in the Eocene.

Adult falcons have thin, tapered wings, which enable them to fly at high speed and change direction rapidly. Fledgling falcons, in their first year of flying, have longer flight feathers, which make their configuration more like that of a general-purpose bird such as a broadwing. This makes flying easier while still learning the aerial skills required to be effective hunters like the adults.

The falcons are the largest genus in the Falconinae subfamily of Falconidae, which also includes two other subfamilies comprising caracaras and a few other species of "falcons". All these birds kill prey with their beaks, using a tomial "tooth" on the side of their beaks—unlike the hawks, eagles and other larger birds of prey from the unrelated family Accipitridae, who use talons on their feet.

The largest falcon is the gyrfalcon at up to in length. The smallest falcon species is the pygmy falcon, which measures just . As with hawks and owls, falcons exhibit sexual dimorphism, with the females typically larger than the males, thus allowing a wider range of prey species.

As is the case with many birds of prey, falcons have exceptional powers of vision; the visual acuity of one species has been measured at 2.6 times that of human eyes.

Taxonomy

The genus Falco was introduced in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae. The type species is the merlin (Falco columbarius). The genus name is Late Latin meaning a "falcon" from , , meaning "a sickle", referring to the claws of the bird. In Middle English and Old French, the title refers generically to several captive raptor species. (). A falcon chick, especially one reared for falconry, still in its downy stage, is known as an eyas (sometimes spelled eyass). The word arose by mistaken division of Old French , from Latin presumed (nestling) from (nest). The technique of hunting with trained captive birds of prey is known as falconry.

Compared to other birds of prey, the fossil record of the falcons is not well distributed in time. For years, the oldest fossils tentatively assigned to this genus were from the Late Miocene, less than 10 million years ago. This coincides with a period in which many modern genera of birds became recognizable in the fossil record. As of 2021, the oldest falconid fossil is estimated to be 55 million years old. Given the distribution of fossil and living Falco taxa, falcons are probably of North American, African, or possibly Middle Eastern or European origin. Falcons are not closely related to other birds of prey, and their nearest relatives are parrots and songbirds.

Overview

Falcons are roughly divisible into three or four groups. The first contains the kestrels (probably excepting the American kestrel); the tails of the large falcons are quite uniformly dark grey with inconspicuous black banding and small, white tips, though this is probably plesiomorphic. These large Falco species feed on mid-sized birds and terrestrial vertebrates.

Very similar to these, and sometimes included therein, are the four or so species of hierofalcon (literally, "hawk-falcons"). They represent taxa with, usually, more phaeomelanins, which impart reddish or brown colors, and generally more strongly patterned plumage reminiscent of hawks. Their undersides have a lengthwise pattern of blotches, lines, or arrowhead marks.

While these three or four groups, loosely circumscribed, are an informal arrangement, they probably contain several distinct clades in their entirety.

A study of mtDNA cytochrome b sequence data of some kestrels

  • Falco sp. (Early
  • Falco oregonus (Early/Middle Pliocene of Fossil Lake, Oregon) – possibly not distinct from a living species
  • Falco umanskajae (Late Pliocene of Kryzhanovka, Ukraine) – includes "Falco odessanus", a nomen nudum<!--- not italicized -->
  • Falco antiquus (Middle Pleistocene of Noailles, France and possibly Horvőlgy, Hungary)

Several more paleosubspecies of extant species have also been described; see species accounts for these.

"Sushkinia" pliocaena from the Early Pliocene of Pavlodar (Kazakhstan) appears to be a falcon of some sort. It might belong in this genus or a closely related one.

The supposed "Falco" pisanus was actually a pigeon of the genus Columba, possibly the same as Columba omnisanctorum, which, in that case, would adopt the older species name of the "falcon".

Further reading

  • Falconidae videos on the Internet Bird Collection, ibc.lynxeds.com
  • The Raptor Resource Project – Peregrine, owl, eagle and osprey cams, facts, and other resources, raptorresource.org

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