A medium-sized, blackish brown swift with a square tail, Sooty Swift is normally found flying over montane or tropical, lowland, evergreen forest, and second-growth scrub. Its distribution lies primarily in eastern Brazil, and also includes eastern Paraguay and northeastern Argentina. Sooty Swift spends most of the day on the wing, in groups of 3-6 individuals, hunting for flying insects. Like other species of Cypseloides, the Sooty Swift nests on canyon walls or vertical cliff faces and lays only one egg per clutch. Despite limited information on the species’ overall abundance, the Sooty Swift's population is believed to be stable, and consequently has not been placed on any threatened species lists.