Annemarie van der Marel , Xavier Francis, Claire L. O'Connell, Cesar Omar Estien, Chelsea E Carminito, Elizabeth A. Hobson

Dominance hierarchies direct and structure aggression in a myriad of species. Recent computational approaches have been able to detect additional aggression patterns within animal dominance hierarchies based on relative rank differences between individuals. Within species, distinct groups can follow different social dominance patterns, indicating that these patterns should not be thought of as a species-specific characteristic, but rather as a characteristic of that group. Yet, we know little about how and why a particular social dominance pattern emerges within a group, why groups show variation in their patterns, and whether these patterns are flexible. A better understanding of the conditions under which a group might shift from one pattern to another would provide insight into the flexibility of these group-level patterns. We tested whether the removal and reintroduction of a single key group member could be sufficient to trigger a shift in the social dominance pattern in a captive group of monk parakeets (Myiopsitta monachus). We found that the group was more resilient to the removal of a top-ranked individual but responded more consistently to the reintroduction of those key individuals. Using an experimental approach, we determined how social upheaval alters the information in groups and drive species to use more complex rules.