A swiftlet of the western Lesser Sunda Islands. It occurs in forest and dense habitats and feeds on invertebrates.
It has a dark mantle and wings with a blue-green gloss, a dusky-gray throat, white lower underparts, and white spots on the black tail.
It lives in forest and dense vegetation and feeds on invertebrates.
The Sumba subspecies sumbae has broader off-white feather edges on the rump and lower back and more white on the belly, with fewer, rounder dark markings on the lower breast and flanks.
The Sumba subspecies sumbae has a proportionally slightly shorter tail than the nominate form and an unfeathered hind toe.
An extinction-risk assessment has not been added yet.