The Plain swift (Apus unicolor) is a medium-sized bird belonging to the swift family Apodidae. It is an aerial insectivore found primarily in the Macaronesian archipelago, specifically the Canary Islands and Madeira. As its name suggests, it is characterized by its relatively uniform dark plumage, lacking the distinct pale throat patch often seen in other swift species.
Taxonomy
The Plain swift was first described by American ornithologist John Gould in 1840. Its scientific name, Apus unicolor, translates to "footless" (referring to the belief that swifts lacked feet, or more accurately, that their small feet are not used for walking) and "of one color," respectively, aptly describing its uniform plumage. It belongs to the order Apodiformes, which includes swifts and hummingbirds, and the family Apodidae, encompassing all swifts.
Description
The Plain swift is approximately 14-15 cm (5.5-6 inches) in length with a wingspan of around 35 cm (14 inches). Its plumage is almost entirely uniformly sooty brown or blackish, with only a very faint hint of paler feathers on the chin and throat that is not conspicuous. This lack of a prominent white or pale throat patch is a key feature distinguishing it from the similar Common swift (Apus apus), which overlaps in range during migration.
It possesses the typical swift body plan: long, slender, scythe-shaped wings designed for rapid, agile flight, and a short, forked tail. Its flight is strong and direct, often involving swift glides.
Habitat and Distribution
The Plain swift is endemic to the Macaronesian islands in the Atlantic Ocean. Its primary breeding grounds are the Canary Islands (Spain) and Madeira (Portugal). During the non-breeding season, a significant portion of the population is believed to migrate south to mainland Africa, specifically to Sub-Saharan West Africa, though its exact wintering grounds and migratory routes are not as well-documented as those of some other swift species.
It typically inhabits rocky cliffs, ravines, gorges, and coastal areas where it finds suitable crevices and cavities for nesting. It can also be found foraging over towns and open country.
Behavior and Diet
Like all swifts, the Plain swift is highly aerial, spending most of its life on the wing. It feeds exclusively on insects and spiders caught in flight, a behavior known as aerial insectivory. It often forages in flocks, sometimes mixed with other swift species, soaring and maneuvering gracefully to capture prey.
They are gregarious birds, especially during the breeding season, forming colonies at nesting sites. Their calls are typical swift-like screeches, often heard as they dart about their nesting cliffs or over human settlements.
Reproduction
Plain swifts are monogamous and breed colonially. Nests are typically constructed in natural crevices or cavities in cliffs, caves, or occasionally in artificial structures such as old buildings. The nest itself is a shallow cup made from salivary secretions mixed with airborne debris such as feathers, plant material, and insect remains.
The female usually lays 2-3 white eggs per clutch. Both parents incubate the eggs and feed the nestlings. The incubation period is around 19-20 days, and the chicks fledge approximately 35-40 days after hatching, depending on food availability.
Conservation Status
The Plain swift is classified as Least Concern by the International Union for Conservation of Nature (IUCN). This status reflects its relatively large breeding range, stable population trend, and lack of immediate, widespread threats. While local populations can be vulnerable to habitat degradation or disturbance at nesting sites, the overall species is not currently considered threatened.