A small dark brown swift with a slender white rump band. Underparts paler than upperside, but overall coloration still uniform brown. A social, aerial species, always seen in flocks on the wing, often mixed with other swifts. Confined to the south Moluccas. Clear, if narrow, white rump band distinguishes this species from Glossy and Uniform Swiftlets. Unbroken, gray-brown underside further differentiates it from the white-bellied Glossy Swiftlet.