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.