Observations and recordings were made of the female songs produced by 4 adult and mated female Kloss’ gibbons (Hylobates klossii) from a site on Siberut Island, the largest island of the Mentawai Island chain in Indonesia. A statistical analysis of song characteristics revealed that individuality occurs throughout the entire song. The implications of these findings, as well as comparisons to similar studies of individuality on other gibbon species, are presente