The plain swift (''Apus unicolor'') is a medium-sized

swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...

. Although this

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

is superficially similar to a

barn swallow The barn swallow (''Hirundo rustica'') is the most widespread species of swallow in the world. In fact, it appears to have the largest natural distribution of any of the world's passerines, ranging over 251 million square kilometres globally. ...

house martin ''Delichon'' is a small genus of passerine birds that belongs to the swallow family and contains four species called house martins. These are chunky, bull-headed and short-tailed birds, blackish-blue above with a contrasting white rump, and w ...

, it is not related to those

passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...

species. The resemblances between the groups are due to

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

reflecting similar life styles. Swifts have very short legs that they use only for clinging to vertical surfaces. They never settle voluntarily on the ground, and spend most of their lives in the air, feeding on

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

s that they catch in their beaks. They drink on the wing. Plain swifts breed in colonies on cliffs, bridges and buildings on the Canary Islands and Madeira, laying two eggs in a saucer-shaped nest made of flowerheads glued with saliva. They are partially migratory, with many birds leaving to winter in mainland

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. Until recently it was thought that the birds wintered on the African coast but recent studies suggest they travel much further to the equatorial forests of Liberia and Guinea, a distance of 2,600 kilometres. Small numbers are also believed to breed in Morocco between Agadir and Essaouira, where a colony was found on coastal cliffs and possibly also in Mauritania where there are frequent sightings Norton, T., Atkinson, P., Hewson, C. & Eduardo Garcia-del-Rey, E. 2018
Geolocator study reveals that Canarian Plain Swifts Apus unicolor winter in equatorial West Africa''African Bird Club''
& ''Sociedad Ornitologica Canaria''. 15 pp This 14–15 cm long species is very similar to the closely related common and

pallid swift The pallid swift (''Apus pallidus'') is a small bird, superficially similar to a barn swallow or house martin. It is, however, completely unrelated to those passerine species, since the swifts are in the order Apodiformes. The resemblances betwe ...

s, which also occur in the archipelagos, and separation is only possible with good views. Like its relatives, it has a short forked tail and very long swept-back wings that resemble a crescent or a

boomerang A boomerang () is a thrown tool, typically constructed with aerofoil sections and designed to spin about an axis perpendicular to the direction of its flight. A returning boomerang is designed to return to the thrower, while a non-returning ...

. It is entirely dark except for an indistinct pale throat patch. It is slimmer and more rakish than the pallid swift, and is darker than that species and lacks the obvious white throat. Distinguishing the plain swift from the similarly plumaged common swift is much more difficult, although juvenile common can be easily eliminated due to its white throat. The plain is slimmer and appears longer winged than the common, and has scaly underparts, difficult to see except with excellent views. The call is a loud dry scream similar to that of the common swift, though possibly higher pitched.

References

* ''Swifts'' by Chantler and Driessens,

External links

* Madeira Birds
Plain Swift
{{Taxonbar, from=Q1096617 Apus (genus) Birds of the Canary Islands Birds of Madeira Birds described in 1830 Taxa named by Sir William Jardine