Recruitment boosts participation and transfers route information during collective migration in ants

Collective behaviors are widespread across the animal kingdom and often crucial to the persistence of social groups. These behaviors emerge from local interactions among individuals, leading to coordinated actions at the group level. When carrying out collective tasks, task participants guide naïve group members to a valuable resource through recruitment behaviours. Recruitment can improve group efficiency if recruited individuals transfer information about completing the task to others (hereafter referred to as information transfer). Task participants can activate others to join the task through recruitment behaviors (which we term activation). In this study, we investigated these two processes using the rock ant Temnothorax rugatulus as a model system. We focused on two recruitment behaviors–social carrying and reverse tandem running– used during nest emigration. We found that reverse tandem runs resulted in both activation of individuals and information transfer to individuals: recruited individuals subsequently recruited others to the task and learned routes from their leaders. In contrast, social carrying did not lead to activation of individuals or information transfer. Together, our results suggest that different recruitment behaviors play distinct roles in group tasks. Understanding the contribution of these processes to recruitment behaviour is crucial for understanding how individual behaviors scale up to influence collective performance.