The Organization of Song in the Agile Gibbon (Hylobates agilis)

The acoustical and organizational features of the singing behaviour of several groups of the monogamous and territorial agile gibbon (Hylobates agilis) were analyzed in detail. The mated adult pairs produce loud and long duet bouts, while the males also produce solo bouts. The duets were found here to be complex, sequentially and interactively organized, while being dominated by the female; whereas the male solos were less complex and there was a distinct progressive elaboration of the phrases as the bout continued. Some functional and evolutionary implications regarding these findings on the songs of this species are discussed.