Beyond the dyad: higher-order structure within cohesive animal groups can reveal novel patterns of subgroup dynamics

Revealing the consequences of social structure in animal societies is largely determined by our ability to accurately estimate functionally relevant patterns of social contact among individuals. Of particular relevance are social contacts that drive and maintain the cohesion of moving animal groups. Prior studies have predominantly built up social structure from dyadic connections, which while effective in open societies, where groups are ephemeral and thus less cohesive, may not be sufficient to characterize the fine-grained structure within more cohesive animal groups. This is because associations or interactions can involve more than two individuals participating together, which current approaches cannot distinguish from independent sets of dyadic connections. Here we applied higher-order temporal network approaches to high-resolution GPS data from every group member in two cohesive groups of vulturine guineafowl, Acryllium vulturinum . By quantifying moment-by-moment association dynamics, we revealed clear sex-biased contributions to the group cohesion. Specifically, males form the cohesive core of the group as they participated in temporally consistent subgroups and tended to occupy forward positions in moving subgroups. Females instead remained peripheral and were more likely to leave subgroups, while also occupying rear positions in moving subgroups. These results reveal a likely pathway to leadership that is independent of dominance rank, whereby the cohesion among males, which were previously found to be more likely to lead group movements, results in subgroups that allow them to more often form a majority. Our study thus demonstrates that subgroup association dynamics derived from high-resolution GPS data can provide insights into the fine-scale spatial and social organization of cohesive groups that may shape processes such as collective movement and leadership.