Falcon

Falcons
Brown Falcon Falco berigora
Brown Falcon
Falco berigora
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Falconiformes
Family: Falconidae
Genus: Falco
Linnaeus, 1758
Species

About 37; see text.
Synonyms
  • Aesalon
  • Lithofalco
  • Tinnunculus Linnaeus, 1766
  • Hierofalco Cuvier, 1817
  • Cerchneis Boie, 1826
  • Hypotriorchis Boie, 1826
  • Rhynchodon Nitzsch, 1829
  • Ieracidea Gould, 1838
  • Hieracidea Strickland, 1841 (unjustified emendation)
  • Gennaia Kaup, 1847
  • Jerafalco Kaup, 1850 (unjustified emendation)
  • Harpe Bonaparte, 1855 (non Lacepède 1802: preoccupied)
  • Dissodectes Sclater, 1864
  • Genaïe Heuglin, 1867 (unjustified emendation)
  • Harpa Sharpe, 1874 (non Pallas 1774: preoccupied)
  • Gennadas Heine & Reichenow, 1890 (unjustified emendation)
  • Nesierax Oberholser, 1899
  • Nesihierax Dubois, 1902 (unjustified emendation)
  • Asturaetus De Vis, 1906 (non Asturaetos Brehm 1855: preoccupied)
  • Plioaetus Richmond, 1908
  • Sushkinia Tugarinov, 1935 (non Martynov 1930: preoccupied) - see below

A falcon (fɔlkən or fælkən) is any species of raptor in the genus Falco. The word comes from their Latin name falco, related to Latin falx ("sickle") because of the shape of these birds' wings.

Contents

Overview

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

Adult falcons have thin tapered wings, which enable them to fly at high speed and to change direction rapidly. Fledgling falcons, in their first year of flying, have longer flight feathers which makes their configuration more like that of a general-purpose bird such as a broadwing. This is to make it easier for them to fly while learning the exceptional skills required to be effective hunters in their adult configuration. A falcon's wings are shaped like a scythe. Common misconceptions of the difference of a scythe and sickle are the cause of the misconception of the shape of the falcons wings.

Peregrine Falcons have been recorded diving at speeds of 114 miles per hour, making them the fastest-moving creatures on Earth.[1] Other falcons include the Gyrfalcon, Lanner Falcon, and the Merlin. Some small falcons with long narrow wings are called hobbies, and some which hover while hunting are called kestrels. The falcons are part of the family Falconidae, which also includes the caracaras, Laughing Falcon, forest falcons, and falconets.

The traditional term for a male falcon is tercel (UK spelling) or tiercel (United States spelling), from Latin tertius = third because of the belief that only one in three eggs hatched a male bird.[3] [4] Some sources give the etymology as deriving from the fact that a male falcon is approximately one third smaller than the female (Old French tiercelet).

A falcon chick, especially one reared for falconry, that is still in its downy stage is known as an eyas[5][6] (sometimes spelt eyass). The word arose by mistaken division of Old French un niais, from Latin presumed *nidiscus ("nestling", from nidus = nest). The technique of hunting with trained captive birds of prey is known as falconry.

As is the case with many birds of prey, falcons are renowned for their exceptional powers of vision; one species has been found to have a visual acuity of 2.6 times that of a normal human. [2]

In February 2005, the Canadian ornithologist Louis Lefebvre announced a method of measuring avian intelligence in terms of their innovation in feeding habits. The falcon and crow family scored highest on this scale.[3]

Systematics and evolution

Compared to other birds of prey, the fossil record of the falcons is not well distributed in time. The oldest fossils tentatively assigned to this genus are 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. The falcon lineage may however be somewhat older than this and given the distribution of fossil and living Falco taxa is probably of North American, African or possibly Middle Eastern or European in origin.

Falcons are roughly divisible into three or four groups. The first contains the kestrels (probably excepting the American Kestrel[4]); usually small and stocky falcons of mainly brown upperside color and sometimes sexually dimorphic; three African species that are generally grey 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) and more elegant species, the hobbies and relatives. These birds are characterized by considerable amounts of dark slaty grey in their plumage; the malar area is nearly always black. They feed mainly on smaller birds.

Third are the Falcon and its relatives: powerful birds, often the size of small hawks, they also have a black malar area (except some very light color morphs), and often a black cap also. Otherwise, they are somewhat intermediate between the other groups, being chiefly medium grey with some lighter or brownish colours on the upper side. They are on average more delicately patterned than the hobbies and if the hierofalcons are excluded (see below), this group contains typically species with horizontal barring on the underside. As opposed to the other groups, where tail colour varies much in general but little according to evolutionary relatedness[5], the tails of the large falcons are quite uniformly dark grey with rather inconspicuous black banding and small white tips, though this is probably plesiomorphic. These large Falco feed on mid-sized birds and terrestrial vertebrates, taking prey of up to 5-pound sage grouse size.

Very similar to these and sometimes included therein are the 4 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. Notably, 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 (Groombridge et al. 2002) 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. The latter species has a malar stripe, but its color pattern - apart from the brownish back - and notably 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 2.5-2 mya, and are apparently 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.

Other studies[6] have confirmed that the hierofalcons are a monophyletic group - and, incidentally, that hybridization is quite frequent at least in the larger species falcon species. Initial studies of mtDNA cytochrome b sequence data suggested that the hierofalcons are basal among living falcons[7]. This is now known to be an erroneous result due to the presence of a numt (Wink & Sauer-Gürth 2000); in reality the hierofalcons are a rather young group, originating maybe at the same time as the start of the main kestrel radiaton, about 2 million years ago. This lineage seems to have gone nearly extinct at some point in the past; the present diversity is of very recent origin, though little is known about their fossil history (Nittinger et al. 2005, Johnson et al. 2007).

The phylogeny and delimitations of the Peregrine and hobbies groups is more problematic. Molecular studies have only been conducted on a few species, and namely 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[8], 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, even though it is entirely distinct biogeographically), as well as at least most of the "typical" hobbies, are confirmed to be monophyletic as suspected[9].

Given that the American Falcos of today belong to the Peregrine group or are apparently more basal species, it seems that the initially most successful evolutionary radiation was an 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.

In conclusion, the origin of today's major Falco groups - the "typical" hobbies and kestrels for example, or the Peregine-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 about 8 to 2.4 million years ago, when the malar-striped kestrels diversified. Some groups of falcons, such as the hierofalcon complex or the Peregrine-Barbary superspecies have only evolved in more recent times; the species of the former seem to be a mere 120.000 years old or so (Nittinger et al. 2005).

Species

Mauritius Kestrel, Falco punctatus. This small falcon was nearly extinct in 1974
Common Kestrel
New Zealand Falcon, a relative of the hobbies
Saker Falcon, a typical hierofalcon
National symbol of Pakistan Air Force

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

Fossil record

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 into this genus or a closely related one (Becker 1987). In any case, the genus name Sushkinia is invalid for this animal because it had already been allocated to a prehistoric dragonfly relative.

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" (Mlíkovský 2002). 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 into this genus. "Falco" readei is now considered a paleosubspecies of the Yellow-headed Caracara (Milvago chimachima).

Footnotes

  1. ↑ "Wildfacts - Peregrine falcon". BBC Science & Nature. Retrieved on 2008-07-06.
  2. ↑ [1] Science 16 April 1976: Vol. 192. no. 4236, pp. 263 - 265 doi:10.1126/science.1257767
  3. ↑ [2] AAAS Annual Meeting, 2005.
  4. ↑ Groombridge et al. (2002)
  5. ↑ For example, tail colour in the Common and Lesser Kestrels is absolutely identical, yet they do not seem too closely related (Groombridge et al. 2002). On the other hand, the Fox and Greater Kestrels can be told apart at first glance by their tail colours, 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.
  6. ↑ Helbig et al. (1994), Wink et al. (1998), Wink & Sauer-Gürth (2000), Wink et al. (2004), Nittinger et al. (2005)
  7. ↑ E.g. Helbig et al. (1994), Wink et al. (1998)
  8. ↑ See Griffiths (1999), Griffiths et al. (2004).
  9. ↑ Helbig et al. (1994), Wink et al. (1998)
  10. ↑ IZAN 45-4033: left carpometacarpus. Small species; possibly closer to kestrels than to peregrine lineage or hierofalcons, but may be more basal altogether due to its age.(Becker 1987, Mlíkovský 2002).
  11. ↑ IMNH 27937. A coracoid of a Merlin-sized species. It seems not close to F. columbarius or the Recent North American species (Becker 1987).
  12. ↑ Fox Canyon Local Fauna, 4.3–4.8 million years ago: see Martin et al. (2000).
  13. ↑ UMMP V27159, V29107, V57508-V57510, V57513/V57514: some limb bones. Slightly smaller than a Merlin and more robust than American Kestrel, and seems not too distant from F. columbarius.(Feduccia 1970)
  14. ↑ A hierofalcon (Mlíkovský 2002)? If so, probably not close to the living species but an earlier divergence that left no descendants; might be more than one species due to large range in time and/or include common ancestor of hierofalcons and Peregrine-Barbary complex (Nittinger et al. 2005).
  15. ↑ NNPM NAN 41-646. Almost complete left tarsometatarsus. Probably a prehistoric hobby, perhaps less specialized for bird hunting.(Sobolev 2003)
  16. ↑ Status, especially distinctness from F. antiquus, requires confirmation (Mlíkovský 2002).
  17. ↑ Supposedly a Saker Falcon paleosubspecies (Mlíkovský 2002), but this is not too likely due to the probable Eemian origin of that species (Nittinger et al. 2005).

References

External links