Common Swift (Apus apus): Facts, Flight and Migration

What does a common swift look like?

A common swift is uniformly blackish brown, with a small pale gray or whitish patch on the chin that is hard to see at a distance. Its long, narrow, swept-back wings form a crescent or boomerang shape in flight, and the short tail is shallowly forked. Males and females look alike, and young birds are slightly paler, with pale edges to the feathers of the forehead and wings.

Up close, the swift has a tiny bill but a very wide gape for catching insects, large dark eyes set in deep sockets, and very short legs. All four toes can point forward, each tipped with a sharp claw. These feet cannot perch on a branch or walk well, but they grip rough walls and the edges of nest holes very firmly.

The scientific name Apus comes from a Greek word meaning “without feet”. Ancient writers thought swifts had no legs at all, because they so rarely saw one on the ground.

How big is a common swift?

The common swift is larger than the swallows and martins it is often confused with, mainly because of its long wings. Its body is compact and streamlined.

Weight changes a lot with the weather. In cold, rainy spells, when flying insects disappear, adults can lose a noticeable share of their body mass within a few days.

Is a swift a type of swallow?

No. Swifts and swallows are a classic example of convergent evolution, where unrelated animals evolve a similar shape because they live in a similar way. Both catch insects in flight, so both have long wings, small bills and wide mouths. Swallows, however, are songbirds (order Passeriformes), while swifts belong to the order Apodiformes, together with the hummingbirds.

In the field, swifts are all dark below, scream rather than twitter, and flicker their stiff wings in fast bursts between long glides. Swallows have pale underparts and more fluttering, flexible wingbeats, and they often perch on wires. Our swallow vs swift guide explains all the differences, and the barn swallow profile describes its look-alike.

Habitat and range

Common swifts breed across almost all of Europe, from Ireland and Portugal to northern Scandinavia and sub-Arctic Russia, and east through central Asia to Mongolia and northern China. They also breed in Morocco and Algeria and in parts of the Middle East. They do not breed on the Indian subcontinent.

Originally, swifts nested in cliffs and in old woodpecker holes in ancient trees, and a few still do, for example in Poland’s Białowieża Forest. Today, most of the European population nests in buildings. They feed wherever there are flying insects: over towns, river valleys, lakes, wetlands and open countryside, sometimes traveling tens of kilometers from the nest in bad weather.

Migration: from Europe to Africa and back

The common swift is a long-distance migrant. Birds from western and central Europe usually arrive in late April or May and leave from late July to mid-August, which means they spend only around three months at the nest. Non-breeders, failed breeders and young birds tend to leave first, followed by breeding males and then females.

Tracking with tiny geolocators has shown that European swifts winter in sub-Saharan Africa, especially in the forest and savanna zones around the Congo Basin and farther south and east. Western populations fly south through Iberia and West Africa, while eastern birds cross the eastern Mediterranean and the Middle East.

A swift can fly at least 200,000 km (124,000 mi) in a year, and a long-lived bird may cover around two million kilometers in its lifetime. For the bigger picture of why birds make such journeys, see why do birds migrate?.

Behavior: life on the wing

The swift is the most aerial bird in Europe. A 2016 study from Lund University in Sweden fitted swifts with small data loggers and found that some individuals stayed airborne for the entire ten months between leaving the nest in late summer and returning the next spring. Others landed only briefly, but even they spent more than 99 percent of that time flying. Our article do swifts ever land? explains how this works.

Swifts are also fast. Scientists in Sweden measured birds in “screaming parties” flying at up to about 111 km/h (69 mph) in level, flapping flight, although their normal traveling speed is much lower. More on that in how fast can a swift fly?.

At dusk and dawn, swifts often climb to heights of a couple of kilometers. Researchers think these “vesper flights” help them read wind and weather conditions and orient themselves.

Screaming parties

On summer evenings, groups of 10–20 or more swifts race low around rooftops and streets, giving piercing, high screams. These screaming parties are one of the best-known sounds of summer in European towns. Birds sitting in their nests often answer the passing group. Females have a slightly higher-pitched call than males.

Later in the evening, many swifts climb high into the sky. Non-breeding birds spend the night aloft, while breeding adults usually return to their nests.

Diet: what do swifts eat?

Swifts eat only what they can catch in the air. Their prey, sometimes called aerial plankton, includes aphids, flies, flying ants, small beetles, hoverflies, moths and young spiders drifting on silk threads. They catch each item with an open mouth while flying.

When feeding chicks, adults store the insects in a pouch in the throat and glue them together with saliva into a ball, called a bolus. A single bolus can contain hundreds of insects. In poor weather, swifts may fly long distances to find food, for example over large lakes where insects swarm, and feeding flocks of thousands can gather over wetlands.

Nesting, breeding and lifespan

Swifts usually nest in colonies, in dark cavities under roof tiles, in gaps under eaves, in wall holes, church towers and nest boxes. The nest is a shallow cup of feathers, plant fluff, seeds and other material caught in the air, stuck together with saliva. Pairs often stay together for years and return to the same nest hole every spring.

Most swifts do not breed until they are about four years old. The female lays two or three eggs, and both parents incubate them for about 18–24 days. The chicks stay in the nest for 37–56 days, a long time for a bird of this size. When food is short, the chicks can lower their body temperature and enter a sleep-like state called torpor, which lets them survive several days with little food.

Young swifts leave the nest fully independent. They drop out of the hole and fly, and they do not return to their parents. Many then head straight for Africa.

How long do swifts live?

For a small bird, the common swift lives a long time. According to ringing data from the British Trust for Ornithology, a swift that survives to breeding age typically lives about nine years. The oldest ringed swift in Britain lived almost 18 years. About 80 percent of adults survive from one year to the next, which is high for a bird of 40 g.

Predators and threats

Adult swifts have few predators, although the Eurasian hobby, a small falcon, can catch them in flight, and peregrines and sparrowhawks occasionally take them. Nests are rarely raided, because the entrance holes are small and usually high up.

The main threats today come from people. Renovation, roof repairs and modern building methods seal up the gaps that swifts nest in, and new houses often have no openings at all. Fewer flying insects, linked to intensive farming and pesticide use, also reduce food. Heat waves can overheat nests under roofs, and long periods of cold, wet weather in summer can starve chicks. Read more in why are swifts declining?.

Conservation status

The IUCN lists the common swift as Least Concern worldwide, because it has a vast range and a very large population. In Europe, however, it is rated Near Threatened on the regional Red List. In the United Kingdom it was moved to the Red List of Birds of Conservation Concern in 2021, after the Breeding Bird Survey recorded a fall of about 70 percent between 1995 and 2024. The UK population was estimated at around 59,000 pairs in 2016.

Conservation work focuses on nest sites. Special swift bricks, which have a nest chamber built into the wall, and swift nest boxes can be added to new and old buildings. Many towns now run swift projects that map nest sites and protect them during building work.

Swifts and people

Swifts have lived alongside people for centuries. In medieval Italy, special nesting holes were built into towers and walls. The heraldic “martlet”, a bird drawn without feet on coats of arms, may have been inspired by swifts or martins. Today, the first screaming swifts of May are celebrated in many European towns as a sign that summer has arrived, and webcams inside nest boxes let thousands of people watch the birds raise their young.