Ranging Behavior of Wild Silvery Lutungs (Trachypithecus cristatus) in the Coastal Forest of West Sumatra, Indonesia

Ranging behavior, including home range use and daily travel distance, provides valuable information on the behavioral responses of primates to their habitats. We evaluated the ranging behavior of wild silvery lutungs (Trachypithecus cristatus) inhabiting a coastal forest in West Sumatra, Indonesia, for 614 h over 15 months in 2018–2021, focusing on the relationships between ranging behavior and activity budgets, dietary composition, and food availability. The annual home range was 8.1 ha (minimum convex polygon) and 11.7 ha (95% kernel), and the mean (± standard deviation [SD]) daily travel distance was 926 ± 385 m. Daily travel distance showed a positive correlation with percent resting and negative correlations with percent feeding and moving. Furthermore, daily travel distance was correlated positively with percent young leaf feeding and negatively with percent mature leaf feeding, ripe fruit feeding, and dietary diversity. In contrast, home range size did not vary significantly across the study period, and we found few significant correlations between home range size and dietary composition or activity budget. The longer daily travel distances in food scarce season are likely due to the lutungs needing to travel further to find trees bearing young leaves. We conclude that the silvery lutungs’ ranging behavior is linked to their high-risk, high-return strategy.