Birds

Swift

Apodidae · also called swifts

Not Evaluated ↓ insectivore Temperate grassland Temperate forest Coasts & shorelines

A swift barely uses the ground. Once a young one leaves the nest it may not land again for two or three years, and an adult only comes down to breed. In between, it does everything in the air: feeds, drinks, gathers nest material, mates, and sleeps, spiralling up at dusk to catnap on the wing a couple of kilometres above the earth.

Overview

Swifts are the family Apodidae, around 100 species, on every continent except Antarctica. They are pure aerial insectivores, catching a fine “plankton” of flying insects and drifting spiders one at a time. The family name means footless — a swift’s four toes all point forward, built only for clinging to vertical surfaces, so it cannot perch or easily take off from flat ground.

The most aerial bird there is

The common swift can stay continuously airborne for up to ten months, and a bird can fly millions of kilometres and land only a handful of times in its life. At dusk swifts climb to 1 to 3 km and sleep in short bursts while gliding, apparently one brain hemisphere at a time.

Spit and echoes

Swifts build nests from airborne material glued with saliva, and the cave swiftlets of Southeast Asia make theirs almost entirely of hardened saliva — harvested for bird’s nest soup. Those cave swiftlets also echolocate in the dark. Because flying insects vanish in cold weather, swift eggs and chicks can drop into torpor and survive days of near-starvation.

Status

Swifts as a family are Not Evaluated, trend decreasing. Many tropical species are common, but the common swift is down ~40 per cent in Britain since the mid-1990s and the chimney swift is falling steeply in North America, both from lost nest sites in renovated buildings and from the wider decline in flying insects.

Swift: common questions

Do swifts really never land?

Once a young swift leaves the nest, it can go two to three years without landing at all, staying continuously airborne until it is old enough to breed and build a nest of its own. Adult common swifts land only to nest, and outside the breeding season they too remain aloft, with tracking studies confirming that a bird can fly for up to about ten months without touching down. During that time the swift feeds, drinks by skimming the surface of water, gathers nest material, mates, and sleeps, all in flight. It is the most fully aerial lifestyle of any bird, more extreme than that of albatrosses or frigatebirds, which do at least come ashore.

How does a swift sleep while flying?

At nightfall, swifts spiral upward to roost at altitude, typically 1 to 3 kilometres up, where the air is calm and predators are absent. There they sleep in brief snatches while gliding in slow wide circles, and evidence from related birds and from the swifts' brain activity suggests they use unihemispheric sleep, resting one half of the brain at a time while the other half keeps them flying and watching for danger, then swapping. Total sleep is only a fraction of what a perching bird gets, and swifts seem to manage on it because the rest of their life is spent in efficient gliding flight that costs little energy.

Why can't a swift take off from the ground?

A swift's whole body is built for flight and for clinging to vertical surfaces, not for standing or walking. Its legs are very short and its four toes all face forward, forming a grappling hook that grips a cliff face, a wall, or the inside of a chimney but cannot support the bird upright or push it into the air. Its wings are also long, stiff, and narrow, ideal in the air but awkward to flap clear of flat ground. A healthy adult swift that ends up on the ground can sometimes scramble to a raised edge and drop off into flight, but many cannot, which is why a grounded swift often needs to be lifted and released from a height by hand.

What is the difference between a swift and a swallow?

They look alike and share the habit of catching insects in fast flight, but they are not related. Swifts are in their own order, closest to the hummingbirds, while swallows are perching birds, or passerines, in the same broad group as sparrows and finches. A swift is larger and darker, usually all sooty brown or black, with long scythe-shaped wings held stiff and swept back, a short forked tail, and a screaming call, and it never perches on wires. A swallow is smaller and often has a pale belly and a red or buff throat, flies with more fluttering, flexible wingbeats, has a deeply forked tail with streamers in the barn swallow, and perches readily on wires and buildings. Their resemblance is convergent evolution toward the same aerial-hunting lifestyle.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published September 10, 2026. Last updated September 10, 2026.

Quick facts

Scientific name: Apodidae
Diet: Exclusively small airborne animals, a fine plankton of flying insects and drifting spiders caught one at a time in the open bill during continuous flight, with a swift gathering the catch into a compressed ball in its throat, held together with saliva, to carry back to the nest
A life spent airborne: The common swift can remain in continuous flight for up to about ten months, and young birds that leave the nest may not land again for two to three years until they first breed, so an individual swift can fly millions of kilometres and touch down only a handful of times in its life
Sleeping on the wing: At dusk, swifts climb to between 1 and 3 kilometres and spend the night there, catnapping in short bursts while gliding in wide circles, apparently resting one half of the brain at a time, then descending at dawn to feed
Legs almost useless on the ground: The family name Apodidae means footless, and although swifts do have feet, all four toes point forward and are built only for clinging to vertical surfaces such as cliffs, chimneys, and hollow trees, so a swift grounded on flat ground struggles to become airborne and is vulnerable
Nests glued with spit: Swifts build their nests from feathers, plant fragments, and other airborne material caught in flight and stuck together with their own saliva, and in the cave-dwelling swiftlets of Southeast Asia the nest is made almost entirely of hardened saliva, which is harvested to make bird's nest soup
Some swiftlets echolocate: The swiftlets that nest deep inside dark caves navigate by echolocation, producing audible clicks and reading the echoes, one of very few birds and the only songbird-adjacent group to do so, which they use only in the darkness and switch off once back in daylight
They can pause development when food fails: Because swifts depend on flying insects, which vanish in cold wet weather, both the eggs and the nestlings can survive days of chilling and near-starvation by dropping into a torpid state, and the chicks resume growth when the parents return with food
Range: Every continent except Antarctica, and among the most widespread of all birds, breeding from the tropics to the edge of the Arctic and wintering in warm regions, over almost every open landscape including cities, forest, grassland, mountains, and coasts, since a swift feeds wherever flying insects are carried on the wind.
Conservation status: Not Evaluated ↓ ≈ Not assessed as a family of around 100 species, and while many tropical swifts are common, several migratory temperate species are in marked decline, with the common swift down by around 40 per cent in Britain since the mid-1990s and the chimney swift falling steeply across North America, both linked to the loss of nest sites as old buildings are renovated or sealed and to a general decline in flying-insect numbers, while some Asian swiftlets are over-harvested for the nest trade in the wild