This species breeds in southern and eastern Australia in a variety of habitats, mostly in open areas, man-made clearings or urban environments, but not desert or dense forest.

The welcome swallow was first described in 1842 by John Gould in his The Birds of Australia[4] as a member of the genus Hirundo, but the first publication is often incorrectly given as in the Proceedings of the Zoological Society of London.

[5][6] Both its species name and common name refer to people welcoming its return as a herald of spring in southern parts of Australia.

These birds are about 15 cm (5.9 in) long, including the outer tail feathers which are slightly shorter in the female.

[8] The call is a mixture of twittering and soft warbling notes, and a sharp whistle in alarm.

[7] Young welcome swallows are buffy white, instead of rufous, on the forehead and throat, and have shorter tail streamers.

[11] This swallow species has been observed nesting in the majority of New Zealand and its surrounding islands, Australia and some parts of Tasmania.

During the winter, the welcome swallow in Australia will move towards the north which places it closer to the equator and warm weather.

[11] The welcome swallow is a self-introduced species from Australia that is believed to have flown over to New Zealand in the early 1900s.

[12] This species is well-adapted for urban and suburban life as well; it is even able to live in high altitude areas due to the provision of nesting materials provided by humans.

[12] During winter, welcome swallows move to a warmer habitat which can provide them enough food and safe shelter.

[7] The nest is an open cup of mud and grass, made by both sexes, and is attached to a structure, such as a vertical rock wall or building.

Buildings, moveable boats and ferries, hollowed-out trees, caves and cliffs, mine tunnels and shafts, as well as underground water tanks have all been observed areas of nesting swallows.

When breeding, they usually work in pairs but often small loose groups to protect their nest and territory, especially against predatory birds.

They often fly fast and low to the ground on open fields in large circles or figure eight patterns.

It has been found welcome swallows have slow growing wings that are not affected by food intake unless they are starving.

[16] It is also believed that the swallow accumulates fat in order to survive time periods when food is scarce or conditions are bad.

[16] The hawk, snake and feral cat are the main predators that hunt welcome swallows.

[15] In swallows' excreta, there are various kinds of bacteria and parasites,[13] which breed in the nest and cause very severe diseases; for example, histoplasmosis, encephalitis, salmonella, meningitis and toxoplasmosis.