Small gray swift with a slightly paler rump and belly. Flight is fast but erratic, with the wings pushed forward. Nests in caves, but can be seen in flight over all habitats on the islands of Mauritius and Reunion. The calls include high-pitched twitters and echolocation clicks. Usually easy to identify, as it is the only resident swift on the Mascarenes. Occurs alongside Mascarene Martin, but distinguished by the gray rather than brown overall coloration, unstreaked underparts, and more erratic flight style.