Collective movement decision-making in primates in crop-raiding contexts

Abstract

Crop-raiding by wildlife species often involves collective group movement and animal decision-making in this context is an important area of investigation as the risks and rewards associated with crop-raiding are greater than those that are likely to occur in wild food foraging situations. Yet, the form of consensus decision-making involved in wildlife crop-raiding has not been evaluated. In the current study, we assessed the decision-making process exhibited by rhesus macaques, a generalist primate species, in the context of crop-raiding. We predicted that rhesus macaques would display unshared consensus decision-making during the higher risk-entailed crop-raiding collective movements. We followed two groups of rhesus macaques and collected data on their movement and foraging behavior during crop-raiding events. The results from our study showed that collective movements in the context of crop-raiding were largely led by single individuals. However, individuals of all age-sex categories successfully led crop-raiding collective movements. Although adult individuals joined adult-initiated raid movements most often, they also joined raids initiated by other age classes. Contrary to our predictions, in crop-raiding contexts, rhesus macaques demonstrated a tendency towards equally shared decision-making for group movements.