Pilot Study on Food-processing Behaviour by Males Long-tailed Macaques on Tinjil Island, Indonesia

Abstract

Non-Human Primates (NHP) have a slow life history compared to other mammals due to their complex brain growth. Brain complexity correlates with behaviour complexity, especially feeding behaviour, which enables primates to have the capability in leaf processing step, tool use, or even food washing. Macaca fascicularis on Tinjil Island is one of the NHP species conducting food-cleaning behaviour. Thus, this study aims to figure out the food-cleaning behaviour differences across the age classes of juvenile and male long-tailed macaques (LTM). The feeding behaviour of two age classes of male LTM through 3 different types of food processing was analysed using focal animal sampling and instantaneous recording methods. Then, the data were statistically analysed using Mann-Whitney and Kruskal-Wallis. We found that both age classes used Step 1 of the processing food type more than other types. Analysis within each age class showed different results that juvenile male LTM had a higher frequency of Step 0 and lower frequency of Step 1 than adult male LTM and vice versa. The result indicates no significant differences in the three food type processing between juvenile and adult male LTM.