The alpine swift (Tachymarptis melba) is a species of swift found in Africa, southern Europe, and Asia. They breed in mountains from southern Europe to the Himalayas. Like common swifts, they are migratory; the southern European population winters further south in southern Africa. They have very short legs which are used for clinging to vertical surfaces. Like most swifts, they never settle voluntarily on the ground, spending most of their lives in the air living on the insects they catch in their beaks.

Taxonomy

The alpine swift was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae. He placed it with the swifts in the genus Hirundo and coined the binomial name Hirundo melba. Linnaeus specified the type locality as Gibraltar. Linnaeus based his account on "The greatest martin or swift" that had been described and illustrated in 1743 by the English naturalist George Edwards in his book A Natural History of Uncommon Birds. Edwards's specimen had been shot on the rock of Gibraltar. The alpine swift is now placed together with the mottled swift in the genus Tachymarptis that was introduced in 1922 by the South African zoologist Austin Roberts. The genus name is from the Ancient Greek ταχυς/takhus meaning "fast", and μαρπτις/marptis meaning "seizer". The etymology of the specific epithet melba is uncertain, but it may be a short form for melanoalba or melalba, from Ancient Greek μελας/melas, μελανος/melanos meaning "black" and Latin albus meaning "white".

Ten subspecies are recognised: with a wingspan of 54–60 cm with broad wings and tail with a shallow fork, superficially similar to a large barn swallow or house martin although unrelated to these two species, since swifts are in the order Apodiformes. The resemblance could be due to convergent evolution, reflecting similar lifestyles. Upper parts are olive-brown with sharp and long wings with wing-tips appearing blacker; underparts with white throat (often not easily visible) The same situation has been found for Komarowa Cave near Częstochowa, Poland during a period about 20,000–40,000 years ago.

These apodiformes build their nests in colonies in a suitable cliff hole or cave, laying two or three eggs. Swifts will return to the same sites year after year, rebuilding their nests when necessary, and pairing for life. Young swifts in the nest can drop their body temperature and become torpid if bad weather prevents their parents from catching insects nearby. They have adapted well to urban conditions, frequently nesting in old buildings in towns around the Mediterranean, where large, low-flying flocks are a familiar feature there in summer. Alpine swifts have a short forked tail and very long swept-back wings that resemble a crescent or a boomerang but may (as in the image) be held stretched straight out. Their flight is slower and more powerful than that of their smaller relatives, with a call that is a drawn-out twittering (listen at right).

Alpine swifts are readily distinguished from the common swifts by their larger size and their white belly and throat. They are around twice as big as most other swifts in their range, about in length, with a wingspan of and a weight of around . By comparison, the common swift has a wingspan of around . They're largely dark brown in colour with a dark neck band that separates the white throat from the white belly.

Juveniles are similar to adults, but their feathers are pale edged.

thumb|Eggs of Tachymarptis melba

Distribution and habitat

It is a polytypic species found all year-round in eastern and southern Africa, Madagascar, western peninsular India and Sri Lanka, with larger non-breeding distributions in western, eastern and southern Africa, parts of the western edge of the Arabian peninsula, and breeding across southern Europe in the west across Turkey, northwards through the Caucasus and along the east coast of the Black Sea to the Crimean peninsula and Central Asia up to Turkestan and to the south along Iran and Afghanistan up to Balochistan in Western Pakistan and further east along the Himalayas. Brazil, Barbados, Puerto Rico, French Guiana, Saint Lucia, and Guadeloupe.

Behaviour and ecology

It has a powerful and rapid flight with deep slow wing beats. Alpine swifts spend most of their lives in the air, living on the insects they catch in their beaks. They drink on the wing, but roost on vertical cliffs or walls. A study published in 2013 showed Alpine swifts can spend over six months flying without having to land. All vital physiological processes, including sleep, can be performed while in air. In 2011, Felix Liechti and his colleagues at the Swiss Ornithological Institute attached electronic tags that log movement to six alpine swifts and it was discovered that the birds could stay aloft in the air for more than 200 days straight.

Breeding

Alpine swifts breed in colonies of up to hundreds of pairs on cliffsides or buildings. They habitually return to the same colonies year after year, and are considered monogamous, featuring a relatively low rate of extra-pair paternity among females. They breed once a year, each clutch having 1-4 eggs. The brood is incubated and fed by both parents. The hatchlings fledge at about 50 days after hatching.

Sexual dimorphism is cryptic, with males having a slightly longer tail fork– about 7% longer on average.

Food and feeding

The alpine swift's diet consists mainly of arthropods, principally insects but also spiders. Insects across 10 orders and 79 families were documented in the diets of individuals from Africa and Europe, with the homoptera, diptera and hymenoptera being the most often consumed.

References

  • Ageing and sexing (PDF; 2.3 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze
  • Alpine swift - Species text in The Atlas of Southern African Birds