Cook's swift (Apus cooki) is a small bird, superficially similar to a house martin.

The resemblances between the groups are due to convergent evolution reflecting similar life styles.

Cook's swifts breed in limestone caves of Thailand, Myanmar and Indochina.

The species has a green iridescence, a shallow tail fork and is a short distance migrant.

They can be distinguished from a partially leucistic common swift by the deeper tail fork, longer wings, bigger head and larger white throat patch.