Colomer-Vilaplana, A.; Williams, T. C.; Glaser, S. M.; Grueter, C.

Tandem running in ants is a form of social learning that involves an informed leader guiding a naive nestmate to a valuable resource, such as a nest site or a food source. Little is currently known about what tandem followers learn and how socially acquired navigational information affects future trips. While some studies suggest that tandem followers learn the resource position but not the route taken by the tandem pair to reach the resource, more recent evidence contradicts this view. We studied tandem running in foraging acorn ants Temnothorax nylanderi and provide evidence that tandem followers socially learn routes from their leaders and later use these routes when travelling between their nest and a food source. Followers that became tandem leaders themselves then guided their follower along the same routes in 90% of tandem runs, demonstrating that navigational information can spread in a forager population through sequential social learning. Ants increased their travelling speed, but not path straightness over successive trips. We also found that ants needed less time on subsequent trips if they experienced longer-lasting tandem runs, suggesting that longer lasting tandem runs allow followers to learn routes more efficiently. Adding visual cues did not affect most of the quantified variables, and we currently know little about the cues used by T. nylanderi during navigation. We discuss how the visual environment inhabited by different species might affect the importance of route learning during tandem running.