Raw Data: Reconciliation in captive zebra species

In social mammals, reconciliation, the peaceful reunion of former opponents after a conflict, serves to repair damaged relationships, reduce stress among the individuals involved and decrease the likelihood of renewed aggression. The aim of our study was to investigate whether plains zebras (Equus quagga) and Grevy´s zebras (E. grevyi) show reconciliation after intragroup aggressive events, and to identify factors facilitating this process. Based on literature in other species, we predicted that reconciliation would be more likely when former opponents had a higher relationship quality (Composite Sociality Index), when the aggressor had a lower rank, after unidirectional aggression, and following less intense conflicts. Additionally, given their typically more stable groups, we predicted that plains zebras would be more likely than Grevy's zebras to show reconciliation. We conducted behavioural observations on a group of plains zebras (n=4, 1 male and 3 females) at the Barcelona Zoo, Spain, and on a group of Grevy´s zebras (n=7, 1 male, 4 females, 2 juveniles) at the Leipzig Zoo, Germany, documenting all aggressive conflicts and affiliative post-conflict behaviours. In line with our predictions, reconciliation was more likely when former opponents had a higher relationship quality and when the aggressor had a lower rank. However, we found no differences between species and no effect of the directionality and intensity of conflicts on the probability of reconciliation to occur. These findings support the hypothesis that reconciliation contributed to group stability by repairing social relationships after conflicts and reducing the risk of renewed aggression, and suggest evolutionary continuity in patterns of reconciliation in mammals.