glansseiler Hirundapus celebensis

A huge swift of lowlands and mountains, one of the fastest-flying birds in the world. Mainly black with a purplish-blue gloss, an obvious white triangle under the base of the tail, and two pale marks at angles to each other in the center of each wing. Square tail has spines that are difficult to see; tail is sometimes held closed into a point. Distinguished from other swifts in its range by much larger size and by the white under the base of the tail. Voice unknown.