Barn Swallow (Hirundo rustica): Facts, Migration and Nests

What does a barn swallow look like?

An adult barn swallow is glossy steel blue above with a rusty red forehead, chin and throat. A dark blue band crosses the upper breast, and the underparts range from creamy white in Europe to deep cinnamon in North America. The most famous feature is the deeply forked tail with two long outer feathers, called streamers, and a row of white spots across the spread tail.

Males and females look similar, but females have shorter streamers, slightly duller blue plumage and paler underparts. Young birds are browner above, have a paler orange face and lack the long streamers, which makes them easy to confuse with other swallows in late summer.

Scientists recognize eight subspecies. The European form (H. r. rustica) has whitish underparts and a complete breast band, while the North American form (H. r. erythrogaster) is reddish below with a narrower, often broken band. East Asian birds (H. r. gutturalis) have whitish bellies and a chestnut breast. In Britain and Ireland, the species is simply called “the swallow”.

How big is a barn swallow?

The barn swallow is a light, slender bird built for long flights rather than strength. Its long, pointed wings make it look larger in the air than it really is.

Barn swallows are not record-breaking fliers. Their normal hunting speed is around 40 km/h (25 mph), and short bursts can reach roughly 70 km/h (45 mph). The superficially similar common swift is larger, heavier and faster, even though the two birds are not related. The main differences are explained in our swallow vs swift guide.

Habitat and range

Barn swallows breed in open country with low vegetation: pastures, meadows, farmland and wetland edges, ideally with water nearby and open buildings for nesting. They avoid dense forest, steep mountains and the centers of big cities. The breeding range covers almost all of Europe, temperate Asia, North Africa, the Middle East and North America from Alaska to southern Mexico, from sea level up to about 2,700 m (8,900 ft).

In winter the species spreads across much of the Southern Hemisphere. European birds winter throughout sub-Saharan Africa, Asian birds in India, Southeast Asia, Indonesia and northern Australia, and North American birds in Central America, the Caribbean and South America. Since about 1980, a small population has even begun breeding in Argentina, in the bird’s own winter range.

Two subspecies barely migrate. H. r. savignii lives year-round in the Nile valley of Egypt, and H. r. transitiva of the eastern Mediterranean is partly resident.

What do barn swallows eat?

Barn swallows are insectivores that catch nearly all their food in the air. They hunt low, often only 7–8 m (23–26 ft) above meadows or water, in swooping, twisting flights, and frequently follow cattle, horses, tractors or people to catch the insects they disturb.

In the breeding season, large flies such as horseflies and blowflies make up a large part of the diet, together with aphids, beetles, moths and small wasps. On the wintering grounds in Africa, flying ants and other Hymenoptera become important. Barn swallows even drink and bathe on the wing, skimming the surface of a pond and scooping up water with the open bill.

Their low flight on dull, humid days, when insects stay close to the ground, is the origin of a well-known piece of weather lore, discussed in do swallows fly low before rain?

Migration: an epic journey twice a year

The barn swallow is one of the best-studied long-distance migrants on Earth. Swallows from Britain and western Europe travel to southern Africa, a journey of roughly 10,000 km (6,200 mi) each way. They migrate by day, feeding as they fly, and cross the Mediterranean and the Sahara before spreading out across the African savannas. Birds from eastern Europe and western Asia winter in eastern and southern Africa.

Ringing first proved this route. In December 1912, a swallow ringed at a nest in Staffordshire, England, was found in Natal, South Africa. Today, winter roosts in South African reed beds can hold millions of birds; the reed bed at Mount Moreland near Durban is used by more than three million swallows from all over Europe and western Asia.

European swallows usually reach Britain in late March and April and leave in September and October. North American birds arrive in the southern United States from February and in Canada by May. Find out more in where do swallows go in winter?

Mud nests and breeding

Before buildings existed, barn swallows nested on cliffs and in caves. Today almost all of them nest in human structures: barns, stables, garages, porches, sheds, bridges and culverts. The nest is a neat open cup of mud pellets mixed with grass, carried one beakful at a time and lined with feathers. Building a new nest takes a pair about one to two weeks, so old nests are highly prized and are often repaired and reused for 10–15 years. The details are in how do swallows build their nests?

Males return first in spring, claim a nest site and advertise it with song and circling flights. Females lay two to seven eggs, usually four or five, and incubation takes 14–19 days. The chicks are fed by both parents and leave the nest after 18–23 days, then stay with their parents for about another week. Most pairs raise two broods a year. In Europe the female does almost all the incubation, while in North America the male helps more.

Barn swallows often nest in small, loose colonies, and each pair defends only a few square meters around its nest. In North America, they sometimes nest under osprey nests, where other birds of prey rarely venture.

Why are the tail streamers so long?

The barn swallow’s streamers are a classic example of sexual selection, the process by which features evolve because they help in winning a mate. In experiments in Denmark in the late 1980s, the biologist Anders Pape Møller lengthened or shortened the streamers of male swallows. Males with artificially lengthened tails found mates sooner and fathered more chicks than males with shortened tails.

Long streamers seem to be an honest signal of quality: males with long tails tend to be healthier and live longer, and the length differs by region. In northern Europe, male streamers are much longer than females’ streamers, while in Spain the difference is only about 5 percent. The streamers also help in flight, improving maneuverability during tight turns, so they are not purely ornamental.

Lifespan, predators and threats

Most barn swallows live less than four years. Mortality is high in the first year, when young birds face their first migration, and roughly half the adults die each year. The oldest known wild barn swallow, identified from a ring, lived a little over 11 years.

Adults are fast and agile, but hobbies, peregrine falcons, sparrowhawks and owls catch some, especially at crowded autumn roosts. In Africa, tigerfish have been filmed leaping from the water to grab low-flying swallows. Cats, rats and snakes take eggs and chicks at nests. Long migrations also bring dangers: storms, cold snaps on arrival and drought in the Sahel can kill many birds in a single season.

Conservation status

The IUCN Red List classifies the barn swallow as Least Concern (assessment 2019) because its range is enormous and its population is estimated in the hundreds of millions. The overall trend, however, is downward. Numbers have fallen in parts of Europe and North America, mostly because modern farming offers fewer insects, fewer open barns and fewer livestock yards, and because of droughts on migration routes.

Historically, the species gained from people. Forest clearance created open land, and buildings provided safe nest sites, which allowed barn swallows to spread, including into northern Alberta in Canada during the 20th century. Today, keeping old barns and stables open in summer and leaving nests in place helps local populations.

Myths and facts

Myth: swallows hibernate in mud over winter. For centuries many Europeans, including some scholars, believed that swallows spent the winter asleep at the bottom of ponds. The idea probably came from autumn flocks roosting in reed beds and then vanishing. Bird ringing in the early 20th century proved that they migrate to Africa.

Myth: one swallow makes a summer. The proverb actually says the opposite. It goes back at least to Aristotle, who wrote that one swallow does not make a spring, and it warns against drawing conclusions from a single sign.

Fact: swallows are good neighbors for farmers. A pair and its chicks catch huge numbers of flies around livestock. Old folk beliefs held that destroying a swallow’s nest would make cows give bloody milk, which helped protect nests on farms for generations.

Barn swallows and people

Few wild birds live so closely with people. The barn swallow has nested in human buildings since ancient times; the Roman poet Virgil described the “twittering swallow” hanging its nest from the rafters. Sailors traditionally wore swallow tattoos as a symbol of a safe return home after long voyages.

The barn swallow is the national bird of Estonia and of Austria, and its arrival in spring is celebrated in poems and proverbs across Europe, Asia and North America. For many people, the first swallow over the fields is still the surest sign that summer is on its way.