The composition of the study groups.

Males are scored as adults through size and testis bright colours, while females are scored as adults once they have given birth. Group members that did not fulfil these criteria were scored as juveniles if they were over one year old. The individuals under one year old were categorized as infants and were not included in our analyses. Identity of the model is showed in last column: hierarchical rank (Dom = dominant, Sub = subordinate), age (A = adult, J = juvenile) and sex (F = female, M = male).