Affiliation among subadult males varies between populations of long-tailed macaques

Abstract

The patterns of affiliative interactions between subadult males are not well known. In female philopatric species, like long-tailed macaques, such relationships may be important in fully understanding socioecological contexts and processes. Subadult males have particularly important relationships with other males, often associated with the challenges of dispersal. This study assesses the patterns of affiliation among subadult males by comparing data from two allopatric populations. We collected over 400 hours of behavioral data on 27 total subadult male long-tailed macaques in Bali, Indonesia. We found that patterns of affiliation between subadult males measured by dyadic interaction rates and individual interaction rate composites varied between these populations. We observed significant variation across three domains of affiliative behavior: (1) resting in spatial proximity, (2) allogrooming, and (3) affiliative gesture exchanges. In each context, the subadult males of one population exhibited higher rates of affiliation than the other. We conclude patterns of affiliation between subadult males, and the importance of maintaining those relationships, respond to variation in socioecological contexts that may be population-specific rather than species-specific.