Individual and social learning in tandem-running recruitment by ants

Animals may acquire information socially, but do they also need to learn independently to make effective use of such information? Tandem running is a form of recruitment in certain ants in which one individual leads another to an important resource such as a better nest site. Tandem runs speed information flow because tandem followers typically discover new nest sites much more rapidly than through independent searching. Moreover, tandem followers often go on to lead new tandem runs, thereby recruiting others. However, former tandem followers do not slavishly follow the route they have been shown. Here, we show that individual ants can improve upon the directness and reduce the duration of tandem runs they subsequently lead but do so only if, between being a follower and becoming a tandem leader, they have explored independently. Similarly, an ant that independently discovers a new nest site, and subsequently leads tandem runs to such a discovery, improves upon the route taken only when she has also explored independently after finding the nest site. Thus, we show that learning through independent exploration is important both to individuals and to their society because it augments information gained through tandem runs and is the basis of route improvement. This will further hasten the transfer of information between members of the society, causing more effective information cascades. Tandem running allows one ant to teach another the location of a resource, but to improve their routes, taught ants also need to learn for themselves.