Altruistic behavior in mother-calf pairs of bottlenose dolphins (Tursiops truncatus) and the possible role of the social bond: a preliminary study

Abstract

In this study, we tested two mother-calf pairs of bottlenose dolphins in a helping task. Specifically, we provided dolphins with an enrichment tool based on the rope-pulling task paradigm to obtain a resource. The calves were unable to solve the task and get the resource on their own, and then we evaluated whether their mothers helped them. Moreover, we also evaluated whether the social bond strength among mother and calf, measured with the simple ratio index, may play an important role in determining altruistic behaviors. Our findings show that mothers performed altruistic behaviors toward their calves only when they had a strong social bond with them. Indeed, only a mother had a strong social bond with her calf, and only she acted altruistically. Moreover, as her calf grew, their social bond weakened and the mother stopped performing altruistic behaviors. As a result, our data seem to suggest the strength of social bonds has an important role in determining altruism.