Geographic and Environmental Variation in Activity Budget and Dietary Habits of Javan Langur (Trachypithecus auratus)

Abstract

Environmental and climatic conditions affect food abundance, affecting animals' dietary composition and diversity. Activity budgets are key information for evaluating the feeding strategy of primates. This study aims to analyze the effects of geographic and environmental factors on activity budget and dietary habits of Javan langurs (Trachypithecus auratus) across their geographical range or among forest types. This study’s data were gathered by conducting a web-based survey of the activity budget and dietary habits of the Javan langur. This study analyzed relationships between the geographical/environmental and activity, dietary composition, and social/behavioral aspects by the Spearman’s rank correlation tests and tested differences in the above variables among three forest types by the Kruskal-Wallis tests. The langurs’ diets were composed of foliage (49.0-75.7%), fruits (21.6-48.1%), and flowers (2.7-23.0%). The activities of the langurs were mainly composed of feeding (range: 20.2-44.2%), moving (9.8- 32.1%), resting (9.3-43.6%), and social behavior (2.5-28.9%). There were no significant differences between forest types and activity budget and dietary habits of the langurs and no significant correlations between geographic/environmental variations and their activity budget and dietary habits. The folivorous-based diets and their specialized digestive strategy would be the main reason for the lack of regional variation in activity and dietary habits.