Social behaviours of captive Hylobates moloch (Primates: Hylobatidae) in the Javan gibbon rescue and rehabilitation center, Gede-Pangrango national park, Indonesia

Abstract

Hylobates moloch, Silvery Gibbon occure on the Java island (in the western half of Java), Indonesia. This study presents preliminary data on social behaviours for Silvery Gibbon in captivity. All the individuals had an average active period from 6:30 hr to 16:00 hr (total 9.5 hours). Resting behaviour had the highest percentage (57.05%[plus or minus] 0.45), followed by movement (21.99%[plus or minus] 0.14), feeding ( 15.73%[plus or minus] 0.34), courtship (5.16%[plus or minus] 0.03), calling (2.35%[plus or minus] 0.02), social behaviours (1.6%[plus or minus] 0.09), agonistic behaviours (0.37 %[plus or minus] 0.01), and copulation (0.05%[plus or minus] 0.01). Gibbons showed two peaks of feeding, from 06:35 to 07:30 and from 14:35 to 15:30. Gibbons in the JGC made two types of calls: male solo and female solo calls. Males had a lower time budget for calling behaviour than females. All the gibbons showed four types of locomotor behaviours: brachiating, climbing, jumping (including ricocheting) and bipedal. The most frequent locomotor behaviour was brachiation type. All individuals in the study groups showed autogrooming. Courtship included approach, follow, and contact behavior. The copulation position was dorso-ventral. Stages of copulation consisted of intromission, pelvis thrusting, ejaculation, and dismounting except mounting.