The House Swift, is a small bird, superficially similar to a Barn Swallow or House Martin. It is, however, completely unrelated to those passerine species. The resemblances between the groups are due to convergent evolution reflecting similar life styles.
These birds have very short legs which they use only for clinging to vertical surfaces. House Swifts breed around habitation and cliffs from Africa eastwards through southern tropical Asia to western Indonesia. Unlike the more northerly Common Swift, many birds are resident, but some populations are migratory, and winter further south than their breeding areas. They wander widely on migration, and are seen as rare vagrants in much of Europe and Asia.
House Swifts build their nests in hole in buildings or sometimes on cliffs, laying 1-4 eggs. A swift will return to the same site year after year, rebuilding its nest when necessary.
House Swifts spend most of their lives in the air, living on the insects they catch in their beaks. They drink on the wing, but roost on vertical cliffs or walls. They are notoriously slow risers in the mornings.
House Swifts are readily identified by their small size. Their wingspan is 33 cm compared to the 42 cm of Common Swift. They are black except for a white rump, the white extending on to the flanks. They have a short square tail. The flight is fluttering like a House Martin.