Swallow

Swallow

19, see text.

The swallows and martins are a group of passerine birds in the family Hirundinidae which are characterised by their adaptation to aerial feeding. Swallow is used colloquially in Europe as a synonym for the Barn Swallow.

This family comprises two subfamilies: Pseudochelidoninae (the river martins of the genus Pseudochelidon) and Hirundininae (all other swallows and martins). Within the Old World, the name "martin" tends to be used for the squarer-tailed species, and the name "swallow" for the more fork-tailed species; however, there is no scientific distinction between these two groups. Within the New World, "martin" is reserved for members of the genus Progne. (These two systems are responsible for the Sand Martin being called "Bank Swallow" in the New World.) The entire family contains around 83 species in 19 genera.

The swallows have a cosmopolitan distribution across the world and breed on all the continents except Antarctica. It is believed that this family originated in Africa as hole-nesters; Africa still has the greatest diversity of species. They also occur on a number of oceanic islands. A number of European and North American species are long-distance migrants; by contrast, the West and South African swallows are non-migratory. A few species of swallow and martin are threatened with extinction by human activities, although other species have benefited from human changes to the environment and live around humans.