Swallow vs Swift: How to Tell These Fast Fliers Apart

Key differences at a glance

Swallows and swifts both spend the summer in Europe and North America catching insects in the air, so they are often confused. Up close they are very different birds.

• Swallows are songbirds with colorful plumage, flexible wings, long tail streamers and the ability to perch, walk briefly and gather mud on the ground.
• Swifts are all-dark aerial specialists with extremely long, narrow wings, tiny legs and a short tail. They are even more tied to the sky than swallows.

A third group, the martins, belong to the swallow family. In Europe, the house martin is a smaller, black-and-white swallow with a bright white rump, and it builds closed mud nests on the outside of houses.

Not related: swallows, swifts and hummingbirds

Despite their similar shapes, swallows and swifts are not close relatives. Swallows and martins form the family Hirundinidae, part of the perching birds or songbirds, the same huge order that includes sparrows, warblers and crows. Swifts belong to the family Apodidae in the order Apodiformes, whose other main members are the hummingbirds, such as the ruby-throated hummingbird.

Their likeness is a textbook example of convergent evolution, in which unrelated animals evolve similar features because they live in similar ways. Both groups catch flying insects in short, wide bills that open into a large gape, and both have long, pointed wings for efficient flight.

The scientific name of the common swift, Apus apus, comes from a Greek word meaning “without feet”. Ancient writers believed that swifts had no legs, because they were almost never seen on the ground.

Shape, color and flight

In good light, a barn swallow shows glossy steel-blue upperparts, a brick-red throat, a dark breast band and creamy or cinnamon underparts. The tail is deeply forked with long outer streamers, especially in adult males. The flight is graceful and swooping, often low over fields and water, with frequent turns and flicks of the wings.

A common swift looks black against the sky, although it is actually dark sooty brown with a small pale patch on the throat. Its wings are very long, narrow and swept back like a crescent or a boomerang, and the short tail is only slightly forked. Swifts fly with fast, stiff, flickering wingbeats followed by long glides, and they often feed much higher than swallows.

Size is surprisingly similar in length, but the swift has a longer wingspan of 38–40 cm (15–16 in) and is roughly twice as heavy as a swallow.

Perching, landing and life in the air

Swallows perch everywhere: on telephone wires, fences, rooftops and twigs. They also land on the ground to collect mud for their nests. In late summer, long lines of swallows on wires are a familiar sign of approaching migration.

Swifts never perch on wires. Their four short toes can all point forward, which is ideal for clinging to walls and the inside of nest holes but useless for gripping a wire. Outside the nesting season, common swifts live almost entirely in the air. They feed, drink, collect nest material and even sleep on the wing, and tracking studies have shown that some young swifts stay airborne for about ten months without landing. Read more in do swifts ever land?

Nests and nest sites

Barn swallows build open cups of mud pellets mixed with grass, usually inside barns, stables, garages and sheds, as explained in how do swallows build their nests? They often nest in small, loose colonies around farms.

Swifts cannot collect mud. They catch feathers, seeds and plant fluff in the air and glue them together with saliva into a shallow pad. They nest in dark holes, mostly in buildings, under roof tiles, in gaps in eaves and in old walls, and sometimes in tree holes and cliffs. Modern buildings and roof repairs that block these gaps have caused many swift colonies to disappear.

Calls and sounds

Swallows have a cheerful, twittering song and a sharp “witt-witt” call, and they give anxious alarm calls when a cat or a hawk comes near the nest.

Swifts are best known for their shrill screams. On warm summer evenings, groups of ten to twenty or more birds race around rooftops and streets in noisy “screaming parties”, one of the defining sounds of a European summer in towns.

When each arrives and leaves

In Britain and much of northern Europe, barn swallows arrive first, from late March and April, and stay until September or October, often raising two broods. Swifts arrive later, in late April and May, raise a single brood and leave early, mostly in late July and early to mid August. Both spend the winter in Africa.

So a bird hunting insects over the rooftops of northern Europe in late September is far more likely to be a swallow or a house martin than a swift; by then almost all swifts have gone.

Which is faster?

The swift is the faster flier. Common swifts have been measured at about 111 km/h (69 mph) in level flight during their displays, one of the highest level-flight speeds recorded for any bird. Barn swallows usually hunt at around 40 km/h (25 mph) and reach about 70 km/h (45 mph) at most. For details, see how fast can a swift fly?

Both groups face similar threats. Barn swallows have declined in parts of Europe and North America as farming has changed, while in Britain the common swift is now red-listed as a bird of high conservation concern because of falling numbers. In North America, the chimney swift is listed as Vulnerable by the IUCN.