A small, short-tailed swift over lowland forest and open areas. Stubby-body, pale belly contrasting with short, dark, square tail. Distinguished from other swiftlets by distinctive cut-out in the base of the hindwing and also translucent base to the flight feathers. Less soaring and more ‘twitchy’ flight than other swiftlet species. Voice, typical swiftlike chips, screeches and chatters.