Falconiformes
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 Black-shouldered Kite | ||||||||
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Accipitridae |
The order Falconiformes is a group of about 290 species of birds that include the diurnal birds of prey. Raptor classification is difficult and the order is treated in several ways.
Classification problems
Traditionally, all the raptors are grouped into 4 families in this single order. However, in Europe, it has become common to split the order into two: the falcons and caracaras remain in the order Falconiformes (about 60 species in 4 groups), and the remaining 220-odd species (including the Accipitridae — eagles, hawks, and many others) are put in the separate order Accipitriformes. A prehistoric family known only from fossils are the Horusornithidae.
The idea that Falconiformes should be divided into many orders is because of the suggestion that the order may not share a single lineage that is exclusive of other birds. The most controversial but also most well-supported suggestion, is that Cathartidae are not Falconiformes but are related to the storks, in the separate order Ciconiiformes. However, morphological evidence supports the common ancestry of the Falconiformes, and the Strigiformes may be very close to the Falconiformes as well.
The American Ornithologists' Union reintegrated the New World vultures (family Cathartidae) into Falconiformes in 2007. This goes against the influential Sibley-Ahlquist taxonomy, in which all the raptors are placed into Ciconiiformes, but the Cathartids are considered to be outside the lineage that includes other raptors. While the latter is apparently correct, the "Ciconiiformes" sensu Sibley & Ahlquist are a paraphyletic, artificial assemblage and one of the weakest point of their classification scheme.
Karyotype analysis indicates that New World vultures are indeed distinct, and the Accipitridae stand apart from all other falconiform birds insofar as that their microchromosomes show a high degree of merging to medium-sized chromosomes, which is quite unique in birds (de Boer 1975, Amaral & Jorge 2003, Federico et al. 2005). Whether this has any bearing on the validity of the proposed Accipitriformes is still a matter of dispute, but it at least proves that the accipitrids are a monophyletic group.
Characteristics
Falconiformes are known from the Middle Eocene (the possibly basal genus Masillaraptor from the Messel Pit) and typically have a sharply hooked beak with a cere (soft mass) on the proximodorsal surface, housing the nostrils. Their wings are long and fairly broad, suitable for soaring flight, with the outer 4–6 primaries emarginated.
Falconiformes have strong legs and feet with raptorial claws and an opposable hind claw. Almost all Falconiformes are carnivorous, hunting by sight during the day or at twilight. They are exceptionally long-lived, and most have low reproductive rates.
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 will be more than twice as heavy the size of her mate. With falcons the male tends to be about a third smaller than the female, from which a male falcon is called a tiercel from the Old French word tierce = "third" from Latin tertius. Sexual dimorphism is generally most extreme in specialized bird-eaters, like the Accipiter hawks, and borders on non-existent among the vultures. Monogamy is the general rule, although an alternative mate is often selected if one dies.
Falconiformes are among the most diverse orders in size. The smallest species is believed to be the Black-thighed Falconet, small males of which can weigh only 28 g (1 oz), measure 14 cm (5.5 inches) and have a wingspan of 26 cm (10.3 inches). The largest species is the Cinereous Vulture, at up to 14 kg (31 lbs), 118 cm (46 inches) and 3 m (10 feet) across the wings.
DNA studies[citation needed] mean that it is likely to be some time until a consensus can be achieved.
See also
- Sibley-Ahlquist taxonomy.
References
- Amaral, Karina Felipe & Jorge, Wilham(2003): The chromosomes of the Order Falconiformes: a review. Ararajuba 11(1): 65-73. PDF fulltext
- de Boer, L.E.M. (1975): Karyological heterogeneity in the Falconiformes (Aves). Cellular and Molecular Life Sciences 31(10): 1138-1139. doi:10.1007/BF02326755 (HTML abstract)
- Federico, Concetta; Cantarella, Catia Daniela; Scavo, Cinzia; Saccone, Salvatore; Bed'Hom, Bertrand & Bernardi, Giorgio (2005): Avian genomes: different karyotypes but a similar distribution of the GC-richest chromosome regions at interphase. Chromosome Research 13(8): 785-793. doi:10.1007/s10577-005-1012-7 (HTML abstract)
Other meanings
- For the Dutch falconry suppliers called Falconiformes, see http://www.falconiformes.nl
External links
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Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "Falconiformes". Image Credit.
