Leaders and Followers: Probing the navigational knowledge of followers during ant tandem runs (#872)
In addition to foraging individually, several species of ants guide nestmates to a goal by tandem running. We found that the Australian ant, Camponotus consobrinus, forages both individually and by tandem running to head to the same goal, nest-specific native Australiantrees on which they forage. While paths of solitary foragers and tandem followers showed no differences in heading or straightness, ants in tandem pairs moved at about half the speed of solitary runs. When leaders were experimentally removed, follower ants initially engaged in a systematic search around the point of interruption, following which they either (a) headed directly towards and successfully reached the foraging trees, or (b) continued searching or (c) returned to the nest. The high incidence of followers that successfully navigated towards the foraging trees or the nest on their own provides strong evidence that many tandem followers are in fact experienced foragers. Detailed analysis of the searching behaviour revealed that even seemingly lost followers displayed a directional bias towards the foraging trees in their search path. Our results show that in a foraging context tandem followers need not be entirely naïve towards the goal location.