Common Swift

Appearance

Common Swifts are 16–17 cm long with a wingspan of 38–40 cm and entirely blackish-brown except for a small white or pale grey patch on their chins which is not visible from a distance. They have a short forked tail and very long swept-back wings that resemble a crescent or a boomerang.

The call is a loud scream in two different tone pitches, of which the higher one is from the female and the lower one from the male. They often form 'screaming parties' during summer evenings where about 10-20 Swifts will gather and fly around their nesting area, all calling out to each other, and being answered by other Swifts within the nests. Larger "screaming parties" are formed at higher altituds, especially late in the breeding season. The purpose of these is not known, but it appears to be the case that these parties, or many Swifts in them, will then ascend to sleep on the wing, while still breeding adults tend to spend the night in the nest.

Naming

Their scientific name comes from the Ancient Greek ἄπους, "apous", meaning "without feet". These birds have very short legs which they use only for clinging to vertical surfaces. They never settle voluntarily on the ground, where they would be vulnerable to accidents and predation.

Reproduction

Swifts will occasionally live in old woodpecker nest holes in ancient forests, and it can be surmised that together with cliffs this was their main nest resource, but with the almost complete removal of ancient forest from their nesting range they have adapted to occupy man-made sites and will build their nests of air-borne material caught in flight and bonded with their saliva, in suitable hollows in buildings, under tiles, in gaps beneath window sills, but most typically in the eaves and in gables. Swifts form reasonably faithful pairs that may last for years, and they will return to the same nesting site and partner year after year, rebuilding their nest when necessary. Swift nests degrade naturally over the long period that the birds are absent on migration. Insect species such as clothes moths, carpet and larder beetles will eat them away, sometimes leaving only the most indigestible elements, typically feather shafts, behind.

Young Swifts in the nest can drop their body temperature and other metabolic elements and become torpid if bad weather prevents their parents from catching insects nearby. In this state they may survive for a few days without food.

Food

Except when breeding, Swifts spend their lives in the air, living on the insects they catch in flight. They drink, feed, and often mate and sleep on the wing.

Migration

Like Swallows, Common Swifts are migratory. Their summer breeding range runs from Spain and Ireland in the West across to China and Siberia in the East. They breed as far South as North Africa with a presence in the Middle East in Israel, Lebanon and Syria, across Turkey including the whole of Europe, as far North as Norway, Finland and most of sub-Arctic Russia. They migrate down to Africa by a variety of routes, so far poorly understood, ending up in Equatorial and Sub-Equatorial Africa, excluding the Cape. The map on this page is old and probably reflects the limits of Linnaeus' knowledge at the time; in fact Common Swifts do not breed in the Indian Subcontinent.