The swallow occasionally supplements its diet with caterpillars when food is short. The swallow carries extra food in its mouth to feed its chicks. A pair of swallows can bring about 400 separate meals a day to its chicks. When it is breeding, however, it is very solitary. Several pairs may rest under one roof, but each pair defends only a small area of the enclosure.
Food becomes plentiful in spring, when mating starts.
The female lays three to six eggs after the nest is built. During this period, both parents feed the chicks. There may be two or three broods during a good year. The young from earlier broods of the sparrow help in the rearing of the young. The Swallow s song is a mixture of fluid, twittering notes, often ending with a dry trill that sounds like a watch being wound.