What are leaders made of? The role of individual experience in determining leader-follower relations in homing pigeons

Negotiating joint routes during group travel is one of the challenges faced by collectively moving animals, on spatial scales ranging from daily foraging trips to long-distance migrations. Homing pigeons, Columba livia, provide a useful model system for studying the mechanisms of group decision making in the context of navigation, owing to the combination of their gregarious nature and the depth of our understanding of their individual orientational strategies. Previous work has shown that during paired flight, if two birds' individually preferred routes are sufficiently different, one bird will emerge as leader whom the other follows. What determines the identity of a leader has important implications for the efficiency of a moving collective, since leaders with higher navigational certainty can increase the accuracy of the group. We examined factors contributing to the establishment of leadership/followership, focusing on the role of previous navigational experience. We tested, on a homing task, pairs of pigeons in which the two partners had relatively greater and lesser prior experience, generated through individual training. Analysis of the GPS-tracked routes taken by such pairs revealed a negative correlation between homing experience and the probability that a pigeon would follow a co-navigating partner. Thus, the larger the difference in experience between two partners, the higher the likelihood the more experienced bird would emerge as leader. Our results contribute to a better understanding of the mechanisms and potential payoffs of collective navigational decision making in species that travel in mixed-experience groups. (C) 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.