Large dark swift with long sickle-shaped wings and a forked tail, which is often kept closed in a needle-tipped point while in flight. Black overall with an ashy gray throat and a thin white rump. Distinguished from needletails by proportionally longer wings, longer and more slender body, and much longer tail. The very similar and closely related Pacific Swift has a broader and brighter rump patch and a whiter throat. Faint greenish gloss on the back is diagnostic but difficult to see. Like other ‘fork-tailed swifts’, usually seen in flight over hills, forests, and open areas.