The Role of Sex in Structuring Aggression, Rank, and Hierarchy in Monk Parakeets

In gregarious species, aggressive interactions often mediate the establishment of social rank and dominance hierarchies. Following the assumption that females and males compete under different selection pressures, many studies examine aggression and dominance in each sex separately. However, social selection pressures such as competition for resources or social status may influence the sexes similarly, and more work is needed to directly examine the role of sex in aggression and dominance. To address this, we compared aggression levels, choice of aggression targets, and dominance hierarchies between sexes in captive, mixed-sex groups of highly social monk parakeets (Myiopsitta monachus). We examined interactions at the individual, dyadic, and group levels in 5 groups of 10 individuals each. We asked whether sex predicted aggressiveness, choice of aggression targets, and social rank. We found no evidence that one sex was more aggressive than the other. In most cases, sex did not impact the choice of target in an aggressive interaction. The sex of an individual did not significantly predict the rank they achieved in the group; females and males were equally likely to be high-ranked. Overall, we found that sex had limited impacts on aggression and rank in these mixed-sex groups. Our study provides new insights into social aggression and dominance in monk parakeets by examining both sexes and highlights the importance of studying sex similarities and differences within complex social environments.