An unmistakable, sexually dimorphic, long-tailed cuckoo. The male is glossy-black with a pale bill while the female is dark brown above with white bars and spots, barred underparts, and a strongly speckled throat. Known for the distinctive “ko-el” song of the male. Calls include a “kow-kow-kow-kow” call of the male and the shrieking “kik-kik-kik-kik” call of the female. Present in all types of habitats except dense forests. Mostly solitary, sometimes seen in pairs, and is well known for parasitising the nests of crows. Races differ mainly in the plumage of the females and the amount of gloss on the males.