Easily recognized by pale reddish rump, pale finely streaked throat and breast, and black squared-off undertail coverts. Varies significantly across range, with European and African birds being fairly unstreaked below, while Asian populations have well-streaked underparts; compare carefully with other Cecropis species. Juveniles paler, lack reddish tones; may resemble house-martins but note deeply forked tail. Typically glides on stiff, flat wings, flight quite languid with shallow wingbeats. Builds mud nests in mountains, sea cliffs and on buildings and other structures. Forages over open areas.