the singing of the female kloss's gibbon is considered the most beautiful of all the gibbons' songs. unlike most other gibbon species (except for the javan silvery gibbon, hylobates moloch), kloss's gibbon males and females do not sing duets. males typically sing in the hour before sunrise, while an all-female chorus occurs after sunrise. the singing of the gibbons serves to warn off other animals from their territory, and possibly to strengthen the family bonds.