Alpine Swift (Apus melba)

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Description

There are 20 species of swifts (1) with the Common Swift (Apus apus) being the most familiar swift throughout much of Europe (2). The Alpine Swift is sometimes placed in the genus Tachymarptis along with the Mottled Swift (T. aequatorialis) of Africa, by some authors and on the IUCN Red List (1).

The Alpine Swift is a strong, streamlined bird with dark scythe-like wings and a short, dark, forked tail (3). It has a white belly and a dark brown chest band. The chin and throat are also white, but this can be difficult to see from a distance (3). In length they measure 20 to 23 cm, with a wingspan of 51 to 58 cm. They are bulky birds, weighing 75 to 100 g, twice the size of the Common Swift (A. apus) (3).

Calls

The Alpine Swift has a rising and falling chorus of “ti ti ti titititititi ti ti ti tu”, changing in speed and pitch (3). The Alpine Swift’s calls are not as piercing or as high pitched as those of the Common Swift (2).

Behaviour

Alpine Swifts, like all swifts, are aerial birds, spending most of their lifetime on the wing (4). They sleep while flying and even mate in flight, touching down only to nest and rearing the chicks (5). They are unable to perch as their feet are adapted for clinging to walls and trees (5).

Alpine Swifts are socially monogamous birds and form breeding colonies of a few pairs to several hundred pairs (4). They may also form mixed-species flocks of more than 500 birds with Common Swifts (Apus apus), and Pallid Swifts (A. pallidus) (6). During the breeding season, they forage over large areas, far from their breeding site (6). They catch prey on the wing with an open mouth, often flying over wetlands (3).  Flocks may gather in loud vocal parties over towns, such as in Corfu, (Greece) where they have been known to form colonies of several hundred pairs (6) (2). In flight, wings are held stiffly and wing beats are deeper and slower than the Common Swift.

Habitat

Alpine Swifts may breed in a variety of habitats, from cliffs in mountainous areas and alpine regions, rocky habitats in deep ravines, forests, to rural and urban habitats where they nest in crevices of tall buildings (3) (7). They often hunt over wetland habitats such as rivers and swamps and seasonally flooded grasslands (3) (7).

Breeding

The male and female Alpine Swift make a shallow cup of stems and grass, fixed with saliva, in the cavity of a building or cliff. Breeding season is in April to June, during which one clutch of one to four eggs are laid (4). The male and female take turns incubating the eggs for 20 days, and both parents rear the chicks until they are ready to fledge when they are 50 to 70 days old (4). They are old enough to breed at the age of two to three years (5).

Distribution

The Alpine Swift is native to the Iberian Peninsula, southern and Alpine Europe, Mediterranean Africa and parts of the Middle East, Asia Minor and India (7). Their global population is estimated at one to four million birds, distributed over a range of 7.35 million km2 (7). The European breeding population is more than 140,000 pairs, which is less than half of its global breeding range (7). The largest European populations are in Turkey (7).  In Greece, there are an estimated 1000 to 5000 pairs (7), which breed all over the mainland and most of the larger islands (6).

Migration

Alpine Swifts arrive at their breeding grounds in April and in September they fly south to their wintering grounds in sub Saharan Africa (2).

Feeding

The diet of the Alpine Swift is composed almost entirely of insects and drifting spiders, which are caught on the wing.  The Honeybee (Apis mellifera) is a major prey item of Apus apus. They may hunt around beehives and are able to discriminate between the worker Honeybees that sting and the harmless male honeybees (drones) (8).

Predators

Being aerial birds, Alpine Swifts may fall prey aerial predators such as the Hobby (Falco subbuteo), which is large enough to take swifts and swallows in flight (5).

Conservation status

IUCN Red List =Least Concern (1)

References

Description written by Maite Guignard (2009)

(1)   IUCN (2008) IUCN Red List of Threatened Species [online] Available:

http://www.iucnredlist.org [date accessed: 14/05/2009]

(2)   Jonsson. L. (1992) Birds of Europe, Christopher Helm Ltd.,

(3)   Hume. R. (2002) RSPB Complete Birds of Britain and Europe, Dorling Kindersley, London

(4)   Bize. P., Roulin. A., and Richner. H. (2002) Co-variation between egg size and rearing condition determines offspring quality: an experiment with the alpine swift, Oecologia, 132:231–234

(5)   Mullarney. K., Svensson. L., Zetterstrom. D., and Grant, P.J. (1999) Collins Bird Guide, Harper Collins Publishers, London

(6)   Handrinos. G., and Akriotis. T. (1997) The Birds of Greece, Christopher Helm Ltd., London

(7)   Bird Life International (2008) Species Factsheet: Tachymarptis melba [online] Available:

http://www.birdlife.org [date accessed: 22/05/2009]

(8)   Lack. D., and Source.  D.F.O. (1955) The Food of the Swift, Journal of Animal Ecology, 24 (1): 120-136