Khao Yai white-handed gibbons present during the study period.

*: individual males for which only descriptive analysis is available (seeTable 4);**: H. pileatus female coupled with a lar male for several years;°: animals excluded from analysis (N = 3) because of missing samples;‡: animals excluded from analysis (N = 3) because no male solo songs were recorded (only duets were available).Only adult males were considered in the analysis.