The barn swallow is the most widespread species of swallow in the world. It is one of the first signs of summer, arriving the UK from its wintering grounds in Africa to breed, and often returning to the same nesting site each year. After breeding, swallows gather in huge communal roosts, sometimes thousands strong, when they can be spotted swirling in the sky, or perched on telegraph wires before heading south for winter.
Breeding birds: 860,000 territories
Family: Swallows & martins
Adult male swallows have black plumage with glossy blue on the upperparts and black flight feathers. The deeply forked tail is black with long streamers.
On the underparts, the breast and belly are cream and there is a dark blue collar on the throat. The flight feathers on the underwing are dark grey with cream-coloured coverts, and the undertail coverts are cream with black rectrices. There are white patches on the outer rectrices which form a white band across the tail.
On the head the forehead and chin are orange-red, the crown and nape are dark blue, and the lores and area around the eyes are black. They have short, thin black bills, black eyes and black legs and feet.
Female swallows are similar to the male but with shorter tail streamers and a less distinct blue collar on the throat.
Juvenile swallows are duller than adults with a buff-white forehead and chin, and short tail streamers.
Swallows breed from May to July and produce 2 or 3 broods a season. They nest under the rafters of buildings or ledges on cliff faces. Both male and female build the nest which is a shallow cup open at the top. It is made from mud and dried grass, and lined with softer materials such as feathers and plant down.
Swallows lay 4-5 white eggs with reddish-brown speckles which are incubated mainly by the female for 14-16 days. If she leaves the nest to feed the male may incubate for 15 minutes at a time, but if she dies, the nest is abandoned. Chicks are covered in long, grey down and are fed insects by both parents. After 2 weeks they appear above the edges of the nest with open bills. They fledge at 20-24 days after hatching but return to the nest at night. They are sexually mature at 1 year.
Swallows feed and drink on the wing, catching insects including flies, grasshoppers, crickets, beetles, moths, butterflies and dragonflies. They will often follow tractors to take advantage of disturbed insects.
Swallows arrive in the UK in March and have departed by October. They can see across the UK in areas where there is a good supply of insects such as near open water, farmland. Before migrating they can often be found near reed beds.
Swallows appear to have used man-made structures for their nests for thousands of years. In Virgil’s Georgics written in 29 BC reference is made to the swallow: Ante garrula quam tignis nidum suspendat hirundo (Before the twittering swallow hangs its nest from the rafters).