Dominance and the initiation of group feeding events: the modifying effect of sociality

摘要

Social animals do not benefit equally from being in a group. We show how individuals engage in group foraging differs in relation to their dominance rank and social associations. High and low ranking individuals' likelihood to start a group foraging event depends heavily on how social they are. Understanding how different types of individual arrive to group foraging events can provide clues about benefits animals receive from foraging in a group.Individuals can differ in how much they benefit from being in a group depending on characteristics such as their dominance rank or their behavior. Understanding which categories of individuals influence the decisions of a group could help understand which individuals are benefiting the most. We examine these ideas in wild flocks of black-capped chickadees (Poecile atricapillus), which feature stable group membership and linear dominance hierarchies. We attempt to infer which individuals are influencing group movement by examining how individuals initiate and join foraging events in relation to their dominance rank, exploratory personality type and position within a social network. We find that the influence of dominance on these behaviors heavily depends on the social connections an individual has, and that the effect of exploratory personality was small. Dominant individuals with a high eigenvector centrality were more likely to initiate a foraging event, whereas among individuals with a low eigenvector centrality this relationship was reversed, with subordinates being slightly more likely to initiate a foraging event. Analysis also suggested that individuals with a large number of strong social connections would be less affected by dominance than less social individuals. This suggests a system where individuals might adopt different foraging strategies depending on their position within a social network, and highlights the importance of individuals' social phenotype when studying group decision-making.