Intragroup sociality drives individual participation in intergroup competition in an urban-dwelling nonhuman primate

There is significant variability in the extent to which individuals from group-living species participate in intergroup competition (IGC) over resources. Such variability may be particularly robust in human-impacted environments, wherein anthropogenic resources may strongly impact intergroup overlap and competition. Examining the socio-ecological causal factors driving these differences can shed new lights on animals costs-benefits trade-offs driving engagement in such interactions. Here we use (peri)urban-dwelling rhesus macaques (Macaca mulatta) as model-systems to examine how individual differences in socio-ecological characteristics (i.e., animals sex, rank, and affiliative connections) may influence propensities to participate in IGC in anthropogenic environments. We found that participation was strongly influenced by individuals affiliative connections. Interestingly, monkeys with more coalitionary support partners had higher IGC participation, but this was more pronounced for individuals that are more peripheral in their proximity and multilayer affiliative networks, compared to more socially central individuals. Moreover, males and low-ranking individuals were more likely to participate in IGC. Our findings suggest that differential access to socio-ecological resources likely drives IGC participation. The evaluation of such inter-individual differences in socio-ecological flexibility and decision-making in dynamic environments is critical for future research related to the links between behavioural ecology, health outcomes, and human-wildlife co-existence in anthropogenic landscapes.