A very slender, gray-brown swift with a long, deeply-forked tail that is often held in a closed pointed position. Its erratic flight pattern, comprising frequent direction changes using rapid wingbeats on long, scythe-shaped wings, is distinctive. It nests and roosts in palms and uses its tiny legs with hook-like claws to cling to the undersides of fronds. Less gregarious than other swifts; pairs and small flocks forage over varied habitats from sea level up to 1800 m; prefers lowlands. It gives a high-pitched, metallic “Tre-tit-tit-tit-tit-tit-tit-tit” call, solitarily or in unison with others.