The sociality, ontogeny, and function of corvid post-conflict affiliation

Abstract

Humans and non-humans alike seek support after conflicts by making up with their former opponent (former opponent affiliation) or by affiliating with a bystander (thirdparty affiliation). Post-conflict behaviour has been studied in many mammals but only in two bird species: rooks and ravens. Consequently, the prevalence and function of avian post-conflict affiliation is unknown. My objectives were to expand the study of post-conflict affiliation to more bird species and examine two potential functions of this behaviour. I hypothesised that differences in sociality would influence corvid postconflict affiliation, and that this behaviour would change as individuals developed from juveniles to adults. I predicted that social rooks (Corvus frugilegus) and jackdaws (C. monedula), but not the less social Eurasian jays (Garrulus glandarius), should have post-conflict affiliation because this behaviour should be dependent on the presence of high quality social bonds. Affiliation should only occur with their mate because they are monogamous; the pair-bond being by far the highest quality relationship in the group. My results showed that the social species have third-party affiliation with their mate, while the less social jays have third-party affiliation with anyone. This behaviour became more frequent and lasted longer as jackdaws went from the pair formation stage to sexual maturity. Exploring the function of third-party affiliation, I found that it decreased the likelihood of receiving non-conflict aggression, thus buffering postconflict aggression for jackdaw and rook aggressors, as well as for rook victims. Hypotheses about post-conflict affiliation primarily concern former opponent affiliation and primates. I reviewed post-conflict affiliation across taxa and proposed a broad hypothesis that includes all forms of post-conflict affiliation: former opponent, thirdparty, quadratic, inter-group, and inter-species.