Route learning during tandem running in the rock ant Temnothorax albipennis

Many animals use information from conspecifics to change their behavior in adaptive ways. When a rock ant, Temnothorax albipennis, finds food, she returns to her colony and uses a method called tandem running to lead nestmates, one at a time, from the nest to the food. In this way, naive ants can learn the location of a food source. Less clear is whether they also learn navigational cues that guide them from nest to food, although this is often assumed. We tested this idea by tracing the routes of individually marked ants as they followed tandem runs to a feeder, returned to the nest, and later traveled independently back to the food. Our results show, for the first time, that tandem run followers learn specific routes from their leaders. Independent journeys back to the food source were significantly more similar to the routes on which the ants had been led, compared with the routes taken by other tandem runs. In contrast, the homeward journey did not resemble the tandem run route. These results are consistent with followers memorizing visual cues during the tandem run that are useful for recapitulating the outward journey, but not as effective when facing in the opposite direction on the homeward journey. We further showed that foraging routes improved through individual experience over multiple trips but not through the social transfer of route information via tandem running. We discuss our findings in relation to social learning and integration of individual and social information in ants.