ABS 2023
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Unfamiliarity drives costly aggression in interspecific avian dominance hierarchies
Gavin M Leighton1, Jonathan P Drury2, Eliot T Miller3. 1SUNY Buffalo State University, Buffalo, NY, United States; 2Durham University, Durham, , United Kingdom; 3Cornell University, Ithaca, NY, United States

Although dominance hierarchies often form between species, large-scale analyses of interspecific dominance hierarchies have been rare compared to research on intraspecific dominance hierarchies. To test alternative hypotheses about the formation, maintenance, and consequences of interspecific dominance hierarchies, we employ an especially large, community-scientist generated dataset of displacements observed at feeders in North America. Overall, we find support for the hypothesis that familiaritypredicts adherence to the structure of the dominance hierarchy. Specifically, we find that species with similar foraging ecologies and more fine-scale habitat overlap are more likely to engage in costly aggression over resources. However, among interacting species, familiarity leads to less aggressive encounters than expected and higher directionality of encounters. These results suggest that the previously documented agonistic hierarchy in North American birds is perhaps adaptive, with familiar species typically abiding by their place in the interspecific dominance hierarchy so as to avoid costly aggression.