The Atiu Swiftlet is a small swiftlet endemic to Atiu. It flies over forest, agricultural land and village gardens on the island.
The upperparts and wings are black-brown, with a pale grey rump. The underside is pale grey-brown, darkest below the tail, and the relatively long tail is forked.
It roosts and breeds in cave colonies on Atiu and catches insects over forest, agricultural land and village gardens. It was rarely seen in the dry raised-coral limestone belt except at nesting caves.
Nineteen food boluses carried to chicks on Atiu in December 1987–January 1988 contained 1,893 arthropods: 13 spiders and otherwise insects.
The prey included wasps or other hymenopterans, flies, moths, beetles and cockroaches. The largest item was a 13 mm cockroach, with three 10 mm moths also present.
An extinction-risk assessment has not been added yet.