This is the first study of vocal individuality in male songs of black crested gibbons. The sound
recordings were carried out at two field sites, Pinghe, Ailao Mountains, and Dazhaizi, Wuliang
Mountains, both located in Yunnan province, China. A total of 127 coda phrases of 38 male songs bouts
of eight individual male gibbons were analyzed. Stepwise discriminant function analysis was used to
examine the acoustic individuality of the males. We found that individuality among neighbors was very
pronounced. Moreover, individuality within a site (i.e. among neighbors) is higher than among
individuals between sites. Our finding suggests that black crested gibbons may actively increase their
degree of vocal individuality against that of their immediate neighbors by vocal adjustment.