Swallow

The swallow (Hirundo rustica) is a familiar and welcome sight in temperate latitudes as a harbinger of spring after a long winter. It has entered common parlance in proverbs such as “One swallow does not make a summer”, but a summer without swallows swooping about would be unthinkable to many. 

Distribution and habitat

There are a number of swallow species in different parts of the world, and the bird known simply as the “swallow” in Europe is the “barn swallow” in North America. 

Swallows migrate between Europe and southern Africa, their European sojourn lasting from early April to September or October, when a large local population can fly off together. During the summer they can be seen virtually anywhere within the British Isles. 

Swallows were originally cliff dwellers, but have taken to living near human habitation, especially farms and horse stables where the concentration of flying insects is greatest. 

Appearance

 

The swallow is superficially similar to the swift, although the two species are not related. The main distinguishing feature is the long tail streamers displayed by adult swallows, with male birds having longer streamers than females. Swallows have long pointed wings, although they are not scythe-shaped like those of swifts.

 

The plumage of male and female swallows is similar, being metallic blue above and creamy white below, with the darker colouring extending across the upper chest. The forehead and throat are chestnut red. 

Swallows are small birds, measuring around 18 centimetres (7 inches) in length. 

Behaviour

 

Swallows spend much of their time on the wing, swooping for insects. They are accomplished fliers but do not fly as high or as fast as swifts. They will perch readily on roof ridges, tree branches and telephone wires. They rarely come to the ground, their only reason for doing so being to collect nesting materials; when they do so they can only walk with an ungainly shuffle. 

Swallows are not great songsters but produce a succession of high-pitched trills and twitters. This page on the RSPB website includes a recording of the swallow’s call as well as other information. 

Breeding 

Swallows typically nest in the roof spaces inside farm buildings that have permanent access, such as open barns and horse stables. Adult swallows will return to the same building year after year and will often renovate a previously used nest or build a new one alongside it. Favoured buildings will be close to a water supply that offers a source of soft mud that is used for nest building. 

The nest is an open structure made from mud and saliva with plant matter such as straw incorporated in it. This is then lined with feathers. Five eggs comprise the usual clutch, which is incubated by the female swallow alone for up to 16 days while she is fed by the male. 

When the young birds hatch the parent birds feed them by constantly swooping in and out of the building, which can be disconcerting to any human who is using the entrance at the same time! 

When they have fledged, the swallow families form flocks in places such as reedbeds where they roost when not feeding.

A second, or even a third, brood may be raised, although later clutches are generally smaller than the first one. The young of the first brood may assist in raising the second, and adult swallows which have not bred successfully may give help to their more fortunate neighbours. 

Feeding 

As mentioned above, swallows only take insects on the wing, and it is this behaviour that determines the progress of their migrations. There has to be a food supply at all times, so if the temperature has not reached the point where insects hatch and become active, the swallows will delay their arrival until it does. 

Conservation status

 

Swallows have amber conservation status in the United Kingdom, with the main concern being loss of habitat. One problem that swallows sometimes face is that a farm building could be demolished or its entrance blocked between one breeding season and the next. Although swallows are generally reasonably adaptable at finding a new home this is not always easy, and whereas two broods might have been raised in the old home, a pair might only raise one in a new environment, or be less successful at producing chicks that fledge.

© John Welford