Alexander's swift (Apus alexandri)
|Also known as:||Cape Verde swift|
|French:||Martinet du Cap-Vert|
|Size||Length: 13 cm (2)|
Wingspan: 34 - 35 cm (2)
Alexander's swift is classified as Least Concern (LC) on the IUCN Red List (1).
A small, compact and muscular bird (3) (4), Alexander’s swift (Apus alexandri) is distinguished by having relatively short wings and the shallowest tail-fork of any species in the Apus genus. Alexander’s swift is also paler below than any other swift species within its range (4), and it has a conspicuous, although fairly indistinct, pale-grey to white throat patch (2) (4).
Alexander’s swift is mostly grey-brown on the upperparts, with a darker saddle across the back that contrasts clearly with the paler grey-brown rump and tail. The throat and chin are very pale, with the underparts becoming progressively darker and more grey-brown towards the belly. The head is also grey-brown and there are slightly paler fringes to the feathers on the forehead. The upperparts of the wings are fairly uniform grey-brown, although some of the outer primaries and coverts are darker black-brown. The undersides of the wings are paler (4).
The juvenile Alexander’s swift is similar to the adult, although it has white tips on the inner primary and secondary feathers (2) (4).
Alexander’s swift has a quick, fluttering flight. Its voice is a shrill, high-pitched scream, similar to other swifts, although it is not as piercing and has a somewhat reeling quality (2) (4).
Alexander’s swift is endemic to the Cape Verde archipelago (1) (2) (4). It occurs on most of the islands within the archipelago, except for Santa Luzia (4).
This species is thought to breed mainly on the islands of Santiago, Fogo, Brava, Santo Antão and São Nicolau (4).
Alexander’s swift is known to forage from sea level up to elevations of over 2,800 metres. It occurs in most habitats throughout its small island range (4), from shrubland to lowland and montane forests (1).
This species generally breeds below elevations of 1,600 metres (4).
Swifts and hummingbirds are closely related (4), sharing a unique wing structure which allows them to perform intricate acrobatic manoeuvres in the air. Fairly erratic fliers, swifts are also able to turn sharply mid-flight by varying the speed at which they beat their wings (3). The majority of swifts rarely land, except during the breeding season, instead spending most of their lives in mid-air. Swifts forage for invertebrates while in flight, and some species are even able to sleep and mate on the wing (3). In general, swifts are opportunistic feeders and will exploit a variety of food sources, including swarms and even beehives when available (4). Alexander’s swift is a gregarious species, and is typically seen alone, or in small groups containing up to 30 individuals (4).
Very little is known about the specific breeding biology of this species, and it is possible that the timing of breeding may vary slightly throughout the archipelago. On Santiago, breeding is thought to occur in June, from August to September and from January to March, while breeding occurs mainly in August and September on Brava, and in February on São Nicolau (4).
This species primarily nests in fissures and caves in cliffs (4). It is likely that Alexander’s swift constructs a similar shaped nest to other Apus species, typically a simple, shallow cup placed on the floor of the crevice or hole. Feathers, dried grass and other vegetation are used to build the nest, which is loosely stuck together using the bird’s saliva (5). Alexander’s swift lays a clutch of two plain white eggs. As in other swift species, it is likely that both the male and female take turns to incubate the eggs (4).
There are no known threats to Alexander’s swift. The global population size of this species has not yet been quantified; however, reports suggest that it is common throughout the Cape Verde archipelago (1).
There are no known specific conservation measures currently in place for Alexander’s swift.
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- Coverts: small feathers concealing the bases of larger flight feathers, usually on the wings or tail.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Incubation: the act of incubating eggs, that is, keeping them warm so that development is possible.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.
- Montane forest: forest occurring in mountains.
- Primary feathers: the main flight feathers projecting along the outer edge of a bird’s wing.
- Secondary feathers: the shorter flight feathers projecting along the inner edge of a bird’s wing.
IUCN Red List (December, 2011)
- Beaman, M. and Madge, S. (1998) The Handbook of Bird Identification for Europe and the Western Palearctic. A&C Black Publishers Ltd., London.
- Burnie, D. (2001) Animal. Dorling Kindersley, London.
- Chantler, P. (2000) Swifts. A Guide to the Swifts and Treeswifts of the World. Pica Press, Sussex.
- Lack, D. (1956) A review of the genera and nesting habits of swifts. The Auk, 73(1): 1-32.