Social manipulations trigger shifts in group-level dominance patterns

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

Within dynamic social systems, individuals are expected to change how they interact with each other over time. This social plasticity is critical to understand in groups with dominance hierarchies, where changes in aggression patterns could alter the characteristics of the hierarchy. However, whether changes in individual aggression decisions can alter characteristics of group-level dominance structures, and what factors might lead to these changes, are not well understood. To investigate factors affecting dominance patterns, we experimentally manipulated captive groups of monk parakeets (Myiopsitta monachus) using targeted perturbations to cause social instability through rank-based removals and reintroductions of group members. We found that 1) dominance patterns remained stable when no experimental perturbations occurred, 2) dominance patterns often shifted after experimental perturbations, and 3) the rank of the perturbed individual affected the propensity and types of group-level aggression changes. We showed that removals and especially reintroductions of top-ranked birds had group-level consequences on hierarchical organization. Determining what factors influence social dynamics, such as group-level dominance patterns, can help us understand how animals respond to changing social environments. Predicting the effects of disturbances and identifying network resilience may allow us to prevent future instability from emerging and reduce potential costs upon system collapses.