Black-winged kite

The black-winged kite (Elanus caeruleus), also known as the black-shouldered kite (not to be confused with the closely related Australian species of the same name), is a small diurnal bird of prey in the family Accipitridae best known for its habit of hovering over open grasslands in the manner of the much smaller kestrels. This Palearctic and Afrotropical species was sometimes combined with the Australian black-shouldered kite (Elanus axillaris) and the white-tailed kite (Elanus leucurus) of North and South America which together form a superspecies. This kite is distinctive, with long wings; white, grey and black plumage; and owl-like forward-facing eyes with red irises. The owl-like behaviour is even more pronounced in the letter-winged kite (Elanus scriptus), a nocturnal relative in Australia. Although mainly seen on plains, they are sometimes seen on grassy slopes of hills in the higher elevation regions of Asia. They are not migratory, but show nomadism in response to weather and food availability. They are well adapted to utilize periodic upsurges in rodent populations and can raise multiple broods in a single year unlike most birds of prey. Populations in southern Europe have grown in response to human activities, particularly agriculture and livestock rearing. It is now present in Southwest France.

Taxonomy

thumb|left|Comparison of skull of Elanus with Falco (right)

The black-winged kite was described by the French naturalist René Louiche Desfontaines in 1789 and given the binomial name Falco caeruleus. The type locality is the town of Algiers in Algeria. The black-winged kite is now one of four species placed in the genus Elanus that was introduced in 1809 by the French zoologist Jules-César Savigny. The genus Elanus is distinctive in having very small scales covering the foot and on the underside, scutellate scales are found only under the terminal phalanges. The claw lacks a groove on the underside. The name Elanus is from Ancient Greek for a "kite". The specific epithet caeruleus is the Latin for "blue".

There are three subspecies:

E. c. caeruleus (Desfontaines, 1789) – southwest Iberian Peninsula, Africa, southwest Arabia
E. c. vociferus (Latham, 1790) – Pakistan to east China, Malay Peninsula and Indochina. The underwing secondaries are smoky grey and nearly white in the nominate subspecies.
E. c. hypoleucus Gould, 1859 – Greater and Lesser Sunda Islands, the Philippines, Sulawesi and New Guinea

Description

left|thumb|E. c. caeruleus hovering with whitish underside of the secondaries visible.

This long-winged raptor is predominantly grey or white with black shoulder patches, wing tips and eye stripe. The long falcon-like wings extend beyond the tail when the bird is perched. In flight, the short and square tail is visible and it is not forked as in the typical kites of the genus Milvus. When perched, often on roadside wires, it often adjusts its wings and jerks its tail up and down as if to balance itself. The sexes are alike in plumage. are characters shared with owls and the genus has been considered as a basal group within the Accipitridae. They have a diploid chromosome number of 68 (some older studies claimed 64 for E.c.caeruleus and 66 for E.c.vociferus) with a distinct karyotype with resemblances to the kites and honey buzzards and suggesting a basal position within the diurnal birds of prey.

Distribution and habitat

The black-winged kite is a species primarily of open land and semi-deserts in sub-Saharan Africa and tropical Asia, but it has a foothold within Europe in Spain and Portugal. The species range appears to be expanding in southern Europe and, more recently, also to West Asia. The first records of breeding in Europe were in the 1860s and since then they have become more widespread and populations are on the rise. It is thought that land-use changes, particularly agriculture and pastureland have helped the species. Courtship is noisy and involves chases and once the pair is formed they copulate frequently. Their opportunistic breeding capabilities are also accompanied by irregular patterns of moult. Young birds show "arrested" moult, retaining feathers for a season and then rapidly moulting them in a serial descendent pattern, where more than one primary feather is moulted at the same time. The adult plumage is found after two years.

thumb|left|Calls

thumb|EggsTheir prey includes grasshoppers, crickets and other large insects, lizards, and rodents. Injured birds, small snakes and frogs have also been reported. A feather louse Degeeriella elani is known from the species.

The soft feathers of black-winged kites can lead to adherence with some grass seeds which may be dispersed by the species. However such seeds can pose the risk of entangling their wings.

References

Other sources

External links

(Black-winged Kite or ) Black-shouldered Kite species text in The Atlas of Southern African Birds
Ageing and sexing (PDF; 0.95 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze
Original species description by Desfontaines (in French, 1787), with illustration pl. 15
Illustrations, plate 36 and pl. 37, with description in French by Levaillant (1799).