Effects of individual and group factors on the social relationships of Budgerigars

Social animals often form dynamic relationships with group members, which have been associated with increased social learning, survival and reproductive success. Social relationships can be shaped by both group and individual factors; however, few studies have addressed their combined impact. In this study, we aimed to examine whether group factors and individual factors jointly affect social relations. We selected Budgerigars (Melopsittacus undulatus) as the focal species to investigate the influence of sex, personality, and body length as well as sex ratio and group size on social relationships. The results showed that the birds in 3-individual groups had higher aggression network weighted degree values than those in 5-individual groups. Individuals within opposite-sex groups showed higher levels of aggressive and affiliative interactions than those in same-sex groups. Additionally, females attained higher social ranks despite exhibiting significantly lower aggression behaviors than males. Individuals with longer body lengths exhibited higher aggression network weighted degree values. Our results suggest that group factors primarily influence the social networks, while individual factors play important roles in shaping the social relationships.