Social rules govern vocal competition in the barn owl

Abstract

To resolve the share of limited resources, animals often compete through exchange of signals about theirrelative motivation to compete. When two competitors are similarly motivated, the resolution of con-flicts may be achieved in the course of an interactive process. In barn owls, Tyto alba, in which siblingsvocally compete during the prolonged absence of parents over access to the next delivered food item, weinvestigated what governs the decision to leave or enter a contest, and at which level. Siblings alternatedperiods during which one of the two individuals vocalized more than the other. Individuals followedturn-taking rules to interrupt each other and momentarily dominate the vocal competition. These socialrules were weakly sensitive to hunger level and age hierarchy. Hence, the investment in a conflict isdetermined not only by need and resource-holding potential, but also by social interactions. The use ofturn-taking rules governing individual vocal investment has rarely been shown in a competitive context.We hypothesized that these rules would allow individuals to remain alert to one another's motivationwhile maintaining the cost of vocalizing at the lowest level.© 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd.