Reactivity and social rank in male bighorn sheep (Ovis canadensis)

Group living in animals offers advantages like access to resources, yet also fosters competition, often leading to dominance hierarchies. These hierarchies influence resource distribution and aggression levels. This study investigates individual behavioural traits, including aggression, and their correlation with social rank. Through standardized individual reactivity tests and observational data, we discerned links between dominance rank, group living, and individual behaviour in male Rocky Mountain bighorn sheep (Ovis canadensis). Dominance rank (strongly correlated with age) influenced behaviour, with lower-ranking, younger individuals standing up earlier when approached. More dominant individuals displayed greater boldness, resuming foraging sooner after a human approach. Furthermore, aggression levels correlated with social rank between ages 1 to 6 and then gradually declined with age, with higher-ranking males exhibiting fewer agonistic interactions than middle-aged males. Notably, the study indicates that experimental approaches, in addition to traditional ratings, are viable for understanding personality-dominance associations. While some tests of individual behaviour, such as novel object trials and reactivity assessments, did not yield significant relationships, the research underscores the importance of tailoring tests to the species’ ecological context. The findings contribute valuable insights into the intricate interplay between individuality, dominance hierarchies, and social dynamics. Understanding these relationships enhances comprehension of species’ behaviour and fitness implications.