Social and reproductive behaviour of proboscis monkey Nasalis larvatus (van Wurmb, 1787) at Taman Safari Bogor, West Java

Research on social and reproductive behaviours of proboscis monkey Nasalis larvatus (van Wurmb, 1787) at Taman Safari Bogor has been done. The purposes of the research are to evaluate social interactions between male and female proboscis monkeys, between the females, and to evaluate reproductive behaviours in male and female pairs. Observation methods used were scan sampling and ad libitum sampling with fifteen minutes intervals without pause. The observation time was six hours per day and was done for four weeks in November 2019. Subjects observed in the study were one adult male aged 20 years (J) and two adult females aged 14 years (B1) and 11 years (B2) in a glass cage. Social behaviours observed indicate high affiliative behaviours (average 99.28 %) and low aggressive behaviours (average 0.72 %). Reproductive behaviours were carried out by both pairs with the higher frequency of reproductive behaviours happened between J and B1 than J and B2. Based on the t-test carried out with the value of α = 0.05, the frequency of reproductive behaviours of the pairs significantly different with the value of P < 0.05.