Gray below with a paler belly, a darker throat, and dark patches on the underside of the base of the forewing.

Similar to Gray-rumped Swiftlet, but Pygmy is slightly smaller, with a cleaner white rump band.

Swiftlets that nest in complete darkness in caves can use echolocation, the ability to position an object by reflected sound, used by other animals such as dolphins and bats.

Breeding season varies per island but usually within the window from May to September[2] This is a lowland species thats mostly found near forest and bodies of water.

However, it has a declining population due to deforestation from land conversion, Illegal logging and slash-and-burn farming.