Uncommon dark swiftlet. Endemic to a smattering of the Philippines islands, from Luzon to Mindanao to Palawan. Habitat can be helpful in identifying this confusing species; generally favors ridges and slopes in montane and submontane areas above 700-800 meters. Readily confused with significantly larger Ameline Swiftlet, but present species has a more squared-off-looking tail (fork is shallow and often unnoticeable), tends to fly lower and more erratically, and more often forms flocks. Combination of dark rump, unglossed dark back, and medium size separates this species from Gray-rumped Swiftlet, Pygmy Swiftlet, and Ridgetop Swiftlet. Frequently calls while in flight, giving a squeaky chattering twitter.