A large scimitar-winged swift of valleys, cliffs, and gorges. Nests in buildings and rock crevices; often gives a chattering scream when entering and leaving the nest. Dusky brown with a pale grayish belly, bright white rump, and forked tail. Essentially indistinguishable from the closely related Pacific Swift, but ranges do not overlap; Salim Ali’s Swift is restricted to the highlands of the Qinghai-Tibetan plateau and adjoining foothill regions.