The song of Darwin's Nothura is described as a "whistled song pi-pi-pi-pi-pi pi pi pi", which does not accelerate and descend towards the end (as does the song of Spotted Nothura Nothura maculosa) (Bump and Bump 1969, Fjeldså and Krabbe 1990); and as "a rapid, incessant series of short piping whistles" (Lane, in Schulenberg et al. 2010).
For a representative audio recording with sonogram, see audio
Darwin’s Nothura sings less frequently on hot or on cold, windy days. Singing is most frequent in the morning and in late afternoon. Songs are made up of two to four notes per second and contains from 9 to 64 notes with 15 to 25 being most common. Both sexes sing (Bump and Bump 1969).
When flushed, gives "a disconcerging whistle" (Wetmore 19360 or "a single, stressed scream kyyit" (Fjeldså and Krabbe 1990).