Falcon

Falcons are roughly divisible into three or four groups. The first contains the kestrels (probably excepting the American kestrel);[8] usually small and stocky falcons of mainly brown upperside color and sometimes sexually dimorphic; three African species that are generally gray in color stand apart from the typical members of this group. Kestrels feed chiefly on terrestrial vertebrates and invertebrates of appropriate size, such as rodents, reptiles, or insects.

The second group contains slightly larger (on average) species, the hobbies and relatives. These birds are characterized by considerable amounts of dark slate-gray in their plumage; their malar areas are nearly always black. They feed mainly on smaller birds.

Third are the peregrine falcon and its relatives, variably sized powerful birds that also have a black malar area (except some very light color morphs), and often a black cap, as well. Otherwise, they are somewhat intermediate between the other groups, being chiefly medium gray with some lighter or brownish colors on their upper sides. They are, on average, more delicately patterned than the hobbies and, if the hierofalcons are excluded (see below), this group typically contains species with horizontal barring on their undersides. As opposed to the other groups, where tail color varies much in general but little according to evolutionary relatedness,[note 1] However, the fox and greater kestrels can be told apart at first glance by their tail colors, but not by much else; they might be very close relatives and are probably much closer to each other than the lesser and common kestrels. The tails of the large falcons are quite uniformly dark gray 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 hierofalcons (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[8] identified a clade containing the common kestrel and related "malar-striped" species, to the exclusion of such taxa as the greater kestrel (which lacks a malar stripe), the lesser kestrel (which is very similar to the common, but also has no malar stripe), and the American kestrel, which has a malar stripe, but its color pattern–apart from the brownish back–and also the black feathers behind the ear, which never occur in the true kestrels, are more reminiscent of some hobbies. The malar-striped kestrels apparently split from their relatives in the Gelasian, roughly 2.0–2.5 million years ago (Mya), and are seemingly of tropical East African origin. The entire "true kestrel" group—excluding the American species—is probably a distinct and quite young clade, as also suggested by their numerous apomorphies.

Most members of the genus Falco show a "tooth" on the upper mandible

Other studies[15][16][17][18][19] have confirmed that the hierofalcons are a monophyletic group–and that hybridization is quite frequent at least in the larger falcon species. Initial studies of mtDNA cytochrome b sequence data suggested that the hierofalcons are basal among living falcons.[15][16] The discovery of a NUMT proved this earlier theory erroneous.[17] In reality, the hierofalcons are a rather young group, originating at the same time as the start of the main kestrel radiation, about 2 Mya. Very little fossil history exists for this lineage. However, the present diversity of very recent origin suggests that this lineage may have nearly gone extinct in the recent past.[19][20]

The phylogeny and delimitations of the peregrine and hobbies groups are more problematic. Molecular studies have only been conducted on a few species, and the morphologically ambiguous taxa have often been little researched. The morphology of the syrinx, which contributes well to resolving the overall phylogeny of the Falconidae,[21][22] is not very informative in the present genus. Nonetheless, a core group containing the peregrine and Barbary falcons, which, in turn, group with the hierofalcons and the more distant prairie falcon (which was sometimes placed with the hierofalcons, though it is entirely distinct biogeographically), as well as at least most of the "typical" hobbies, are confirmed to be monophyletic as suspected.[15][16]

Given that the American Falco species of today belong to the peregrine group, or are apparently more basal species, the initially most successful evolutionary radiation seemingly was a Holarctic one that originated possibly around central Eurasia or in (northern) Africa. One or several lineages were present in North America by the Early Pliocene at latest.

The origin of today's major Falco groups—the "typical" hobbies and kestrels, for example, or the peregrine-hierofalcon complex, or the aplomado falcon lineage—can be quite confidently placed from the Miocene-Pliocene boundary through the Zanclean and Piacenzian and just into the Gelasian, that is from 2.4 to 8.0 Mya, when the malar-striped kestrels diversified. Some groups of falcons, such as the hierofalcon complex and the peregrine-Barbary superspecies, have only evolved in more recent times; the species of the former seem to be 120,000 years old or so.[19]

The sequence follows the taxonomic order of White et al. (1996),[23] except for adjustments in the kestrel sequence.

Image	Common Name	Scientific name	Distribution
	Malagasy kestrel	Falco newtoni	Madagascar, Mayotte, and the Comores.
	Seychelles kestrel	Falco araeus	Seychelles Islands
	Mauritius kestrel	Falco punctatus	Mauritius
	Spotted kestrel	Falco moluccensis	Wallacea and Java
	Nankeen kestrel or Australian kestrel	Falco cenchroides	Australia and New Guinea
	Common kestrel	Falco tinnunculus	widespread in Europe, Asia, and Africa, as well as occasionally reaching the east coast of North America.
	Rock kestrel	Falco rupicolus	northwestern Angola and southern Democratic Republic of Congo to southern Tanzania, and south to South Africa
	Greater kestrel	Falco rupicoloides	Namibia, Botswana, Zimbabwe, parts of Angola and Zambia and in much of South Africa
	Fox kestrel	Falco alopex	south of the Sahara from Mali eastwards as far as Ethiopia and north-west Kenya. It occasionally wanders west to Senegal, the Gambia and Guinea and south to the Democratic Republic of the Congo.
	Lesser kestrel	Falco naumanni	Afghanistan and Central Asia, to China and Mongolia.
	Grey kestrel	Falco ardosiaceus	Ethiopia and western parts of Kenya and Tanzania
	Dickinson's kestrel	Falco dickinsoni	Mozambique, Zimbabwe, Zambia and Malawi along with north-eastern South Africa
	Banded kestrel	Falco zoniventris	Madagascar
	Red-necked falcon	Falco chicquera	Africa, India
	Red-footed falcon	Falco vespertinus	southern Russia and Ukraine
	Amur falcon	Falco amurensis	south-eastern Siberia and Northern China
	Eleonora's falcon	Falco eleonorae	Greece,Cyprus, the Canary Islands, Ibiza and off Spain, Italy, Croatia, Morocco and Algeria.
	Sooty falcon	Falco concolor	northeastern Africa to the southern Persian Gulf region
	American kestrel or "sparrow hawk"	Falco sparverius	central and western Alaska across northern Canada to Nova Scotia, and south throughout North America, into central Mexico and the Caribbean.
	Aplomado falcon	Falco femoralis	northern Mexico and Trinidad locally to southern South America
	Merlin or "pigeon hawk"	Falco columbarius	southern Europe and North Africa
	Bat falcon	Falco rufigularis	tropical Mexico, Central and South America, and Trinidad
	Orange-breasted falcon	Falco deiroleucus	southern Mexico to northern Argentina.
	Eurasian hobby	Falco subbuteo	Africa, Europe and Asia.
	African hobby	Falco cuvierii	Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Malawi, Mali, Mozambique, Namibia, Niger, Nigeria, Rwanda, Senegal, Sierra Leone, Somalia, South Africa, Sudan, Swaziland, Tanzania, Togo, Uganda, Zambia, and Zimbabwe.
	Oriental hobby	Falco severus	eastern Himalayas and ranges southwards through Indochina to Australasia
	Australian hobby or little falcon	Falco longipennis	Australia
	New Zealand falcon or Ngarangi or kārearea	Falco novaeseelandiae	New Zealand
	Brown falcon	Falco berigora	Australia and New Guinea.
	Grey falcon	Falco hypoleucos	Australia
	Black falcon	Falco subniger	Australia.
	Lanner falcon	Falco biarmicus	Africa, southeast Europe and just into Asia
	Laggar falcon	Falco jugger	southeastern Iran, southeastern Afghanistan, Pakistan, through India, Nepal, Bhutan, Bangladesh and northwestern Myanmar.
	Saker falcon	Falco cherrug	Ethiopia, the Arabian peninsula, northern Pakistan and western China
	Gyrfalcon	Falco rusticolus	eastern and western Greenland, Canada, Alaska, and Norway.
	Prairie falcon	Falco mexicanus	western North America.
	Peregrine falcon	Falco peregrinus	Cosmopolitan
	Taita falcon	Falco fasciinucha	Kenya

• Réunion kestrel, Falco duboisi – extinct (about 1700)

• Falco medius (Late Miocene of Cherevichnyi, Ukraine)[note 2][24][25]
• ?Falco sp. (Late Miocene of Idaho)[26]
• Falco sp. (Early[27] Pliocene of Kansas)[28]
• Falco sp. (Early Pliocene of Bulgaria – Early Pleistocene of Spain and Czech Republic)[note 3]
• 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[29]
• ?Falco bakalovi (Late Pliocene of Varshets, Bulgaria)[30][31]
• Falco antiquus (Middle Pleistocene of Noailles, France and possibly Horvőlgy, Hungary)[note 4][19]
• Cuban kestrel, Falco kurochkini (Late Pleistocene/Holocene of Cuba, West Indies)
• Falco chowi (China)
• Falco bulgaricus (Late Miocene of Hadzhidimovo, Bulgaria)[32]

Several more paleosubspecies of extant species 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.[24] In any case, the genus name Sushkinia is invalid for this animal because it had already been allocated to a prehistoric dragonfly relative. In 2015 the bird genus was renamed Psushkinia.[33]

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".[25] The Eocene fossil "Falco" falconellus (or "F." falconella) from Wyoming is a bird of uncertain affiliations, maybe a falconid, maybe not; it certainly does not belong in this genus. "Falco" readei is now considered a paleosubspecies of the yellow-headed caracara (Milvago chimachima).