The song of Dark-billed Cuckoo has been described as "six to eight resonant, buzzy kazoo-like notes" (Payne 1997, 2005) or as "a ventriloquial ga-ga-ga-go-go" (Sick 1993).
For a representative audio recording with sonogram, see audio
Also gives another song (?) that is a descending series of guttural notes.
A call of Dark-billed Cuckoo is a dry-sounding buzz that has been described as "dddddrr" (Payne 2005).
In Brazil, Dark-billed Cuckoo vocalizes at night (Sick 1983).