The diet of the welcome swallow comprises a large variety of insects, including flies, beetles, bugs, caddis flies, dragonflies, moths and wasps. This species usually forages alone or in small groups, flying low and fast over the ground and making frequent twists and turns to catch its insect prey. The welcome swallow may also follow other animals, including other birds, to take insects they disturb, and has been recorded feeding at night on moths attracted to lights. Outside of the breeding season, the welcome swallow may gather and roost in large flocks of up to 500 individuals (2) (3).
The breeding season of the welcome swallow runs from July to April, with a peak in breeding activity between September and October (2) (3). Breeding tends to occur earlier inland than on the coast (2). During courtship, the male welcome swallow engages in chases and aerial displays, usually fanning its long tail feathers (2) (3), and the male and female may perch together, twittering to each other (3).
The welcome swallow typically breeds in solitary pairs or sometimes in small, loose groups (2) (3), and each pair aggressively defends the area around its nest (3). The nest is built by both sexes and is usually located on a vertical surface close to an overhang, such as on a wall, cliff, cave or hollow tree, or more commonly on an artificial structure such as a building, culvert, bridge, jetty, veranda, water tank or mine shaft. The welcome swallow builds its nest from mud pellets mixed with grass, and lines it with dry grass, roots, hair and feathers. The nest takes between 6 and 24 days to build, but old nests are repaired and re-used in subsequent years (2) (3).
The female welcome swallow lays a clutch of two to seven eggs, although four to five is most common (2). The eggs are incubated by the female for 14 to 19 days, and both adults feed the chicks, which fledge at 18 to 23 days old. After leaving the nest, the young welcome swallows continue to be fed by the adults and often return to the nest to roost at night for the first few days, or sometimes for the first few weeks. The adult birds may go on to raise a second or even a third brood in the same season, and usually return to the same site to breed in successive years (2) (3).