The most common vocalizations of Mangrove Cuckoo are variations on a series of guttural "awww awww awww awww awww" notes, often rising and then falling slightly in volume and pitch. The drop in pitch of the final series of notes in the sequence may be abrupt, but not always. The first note may be longer and more drawn out than subsequent notes. Vocalizations also may begin with a rapid, almost trilled series of staccato "kuk" notes preceding the “aww” notes. This sequence of rapid "kuk" notes may be delivered alone, too, as a short sequence that sounds like a growl as the notes run together (for a good example of the growl, see seconds 11-13 in ML 145607). The length of vocalization highly variable, depending on which elements are included, but generally ranging from 2-8 seconds.
For a representative audio recording with sonogram, see audio