Social manipulations trigger shifts in group-level dominance patterns

Within dominance hierarchies, individuals often direct aggression based on their own rank and the rank of others. When many group members make the same rank-informed aggression decisions, a broader group-level "dominance pattern" can emerge which further structures aggression within the framework of the dominance hierarchy. However, whether groups can change their group-level dominance patterns over time, and what factors might drive these changes, are not well understood. We investigated aggression dynamics by experimentally manipulating captive groups of monk parakeets (Myiopsitta monachus) using targeted rank-based removals and reintroductions of group members to induce social instability. Dominance patterns often shifted after experimental perturbations but remained stable in their absence. The rank of the perturbed individual affected both individual aggression decisions and the shifts in dominance patterns observed. In particular, reintroductions of top-ranked birds led to marked changes in aggression and shifts in dominance patterns. Understanding the factors that shape these dynamics can help explain how animal societies respond to social disturbance.