Social networks predict immigration success in wild Japanese macaques.

Male migration is common in mammals and comes with associated benefits and costs. Male-male affiliative relationships are behavioural strategies that migrating males can adopt in order to maximise benefits and minimize costs. While we know that such strategies primarily serve to reduce tension, little is known about how they actually affect male immigration success. We investigated the influence of male-male affiliative relationships on immigration success in a group of wild Japanese macaques (Macaca fuscata). We used social network analysis to examine the distribution of male-male affiliative interactions and their association with immigration success. We found that visiting males with high eigenvector centralities and low weighted degree centralities were more likely to be integrated into the group. Other factors such as season, age-class, and dominance rank amongst visiting males did not affect male integration success. Our results suggest that strong male affiliative bonds and a centralized position within the male-male grooming network can predict future integration success of visiting males into a social group through promoting higher tolerance of resident males and reducing aggression risks.