Plain swift (Apus unicolor)

Also known as: Plain-coloured swift
French: Martinet unicolore
GenusApus (1)
SizeLength: 14 - 15 cm (2)
Wingspan: 38 - 39 cm (3)

The plain swift is classified as Least Concern (LC) on the IUCN Red List (1).

A fairly small swift, the plain swift (Apus unicolor) shares its range with both the common swift (Apus apus) and the pallid swift (Apus pallidus), sometimes making it difficult to distinguish the three species from one another in the wild. The plain swift is typically smaller, more streamlined and has slightly narrower wings than its counterparts, as well as a more deeply forked tail (2) (4).

The plumage of the plain swift is mostly dark grey-brown or brown-black, except for an indistinct, mottled, pale grey-brown throat patch. The upperparts have very little contrast, while the underparts are usually slightly darker, sometimes with light scaling or barring. The wings are a fairly uniform dark grey-brown colour, with very little contrast between the inner and outer wing (2).

Juvenile plain swifts are distinctly browner than the adults. The flight feathers and some body feathers of the young plain swift are fringed with white, giving a scalloped effect which is most evident on the crown, the back of the neck and the rump (5). 

The plain swift has a rather distinctive dashing, frantic, fluttering flight (2), usually with faster wing beats and more erratic twisting and turning than the common or pallid swift. Its call is a hoarse, screaming ‘sriii’ (4).

The plain swift is known to breed on Madeira and the Canary Islands (3) (6), and may possibly also breed in coastal Morocco. This species is a vagrant visitor to the Cape Verde archipelago (6).

The plain swift occurs on Madeira all year round (3), but elsewhere this species migrates for the winter, possibly to the coast of North Africa or south of the Sahara (4).

Throughout its breeding range in Madeira and the Canary Islands, the plain swift is found in a variety of habitats, from mountainous ridges and sea cliffs to deep valleys (4). It is frequently found at fairly high altitudes (3), and is also found locally around towns and villages (4). This species typically hunts over woodland and open countryside (4).

On Madeira, the plain swift generally nests in deep clefts in rocks and on sea cliffs. It has also been known to breed on solitary sea stacks off the coast. On the Canary Islands, this species has been found breeding in caves and crevices in the walls of deep gorges and ravines (3).

Swifts have erratic, fluttering flight patterns and are known for their acrobatic aerial displays, being able to turn sharply mid-flight by varying the speed at which they beat their wings (7). Swifts are closely related to hummingbirds (2), and both groups share a unique wing structure that allows them to perform intricate manoeuvres during flight (7).

In general, swifts are opportunistic hunters, feeding mainly on invertebrates, particularly insects and spiders, caught during flight. Swifts will exploit a variety of food sources, including swarms and even beehives when available (2).

The abundance of prey has a significant impact on the breeding biology of swifts, and for most species the timing of breeding typically coincides with the wet season in the tropics and summer in the temperate zone (8). On the Canary Islands, the breeding season of the plain swift is fairly long, usually beginning around March and continuing until August or September (8). The plain swift is a colonial breeder, typically nesting with other individuals in caves or fissures in cliffs (5). The clutch of the plain swift consists of two white eggs, and this species usually produces two broods during a single breeding season (3). As in other swift species, it is likely that both the male and female take turns to incubate the eggs (2). 

Except for the population on Madeira, which tends to remain resident all year round, the plain swift will migrate from the breeding grounds around September to mid-October. This species is presumed to overwinter in Africa, although the exact locations of wintering sites are unknown. The plain swift returns to the breeding grounds between January and March (3).

The plain swift is currently fairly common throughout much of its range and no known major threats have been identified (6).

There are no known specific conservation measures currently targeting the plain swift.

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  1. IUCN Red List (December, 2011)
  2. Chantler, P. (2000) Swifts. A Guide to the Swifts and Treeswifts of the World. Pica Press, Sussex.
  3. Avibirds European Birdguide Online - Plain swift (December, 2011)
  4. Beaman, M. and Madge, S. (1998) The Handbook of Bird Identification for Europe and the Western Palearctic. A&C Black Publishers Ltd., London.
  5. Garcia-del-Rey, E., Gosler, A.G., Gonzalez, J. and Wink, M. (2008) Sexual size dimorphism and moult in the plain swift Apus unicolor. Ringing & Migration, 24: 81-87.
  6. BirdLife International (December, 2011)
  7. Burnie, D. (2001) Animal. Dorling Kindersley, London.
  8. Garcia-del-Rey, E. (2006) Notes on the breeding biology of plain swift Apus unicolor on Gran Canaria, Canary Islands. African Bird Club Bulletin, 13(1): 56-59.