Hani Khoirunnisa, Astuti Kusumorini

The Javan gibbon (Hylobates moloch), an endangered primate endemic to Java, faces increasing threats from habitat loss and human disturbance that alter natural behavior and limit opportunities for direct observation in the wild. Under these conditions, behavioral studies in captivity are essential for understanding activity patterns and human animal interactions that support welfare management and conservation planning. This study aimed to describe the daily activity budget of captive Javan gibbons and to examine their behavioral responses to visitor presence in a zoo environment. Observations were conducted over 31 consecutive days at Bandung Zoo on two individuals: one male (Ukis, 16 years) and one female (Kiskis, 15 years), using ad libitum sampling. Activities were classified into locomotion, resting, feeding, grooming, vocalization, agonistic behavior, and urination. Locomotion was the most dominant activity in both individuals, accounting for 55.30% in the male and 48.27% in the female, followed by resting (19.23% and 22.46%, respectively), while urination and agonistic behaviors were rarely observed. Resting showed the longest average duration, particularly in the female. Environmental conditions during observations ranged from 25–28 °C in temperature and 74–85% in relative humidity and were associated with daily activity patterns, with increased resting during warmer periods. Behavioral responses to visitor presence varied between individuals; the male more frequently displayed agonistic and avoidance-related responses, whereas the female showed more affiliative and neutral behaviors. These findings indicate that captive Javan gibbon behavior is associated with environmental conditions and visitor interactions.