A common, mid-sized swiftlet found over forests and open areas, mainly in the mountains. Slender shape and a notched tail that it sometimes fans. Gray-brown with a contrasting darker tail and forewing. Often seen in flocks and can fly at all levels. Does long glides with tips of the wings held down slightly, and sometimes tipping from side to side. Not safely distinguished from the lowland Uniform Swiftlet. Call, a high-pitch, up-and-down chatter including some grating notes.