Is dominance the only factor determining access to food in an agonistic context? An experiment with captive male mouflon

Abstract

In fulfilling their daily activities, animals must expend the least amount of energy possible while feeding in order to optimise their energy balance. Food is removed by congeners as a result of exploitation competition. When a resource becomes limited, an increase in the probability of interference competition (direct competition for the resource) is triggered. While a high social rank may increase foraging time and resource access, this status also has detrimental facets. To explore the benefits of dominance/aggression in a context where true monopolisation of resources could be advantageous, we tested three hypotheses related to the patchiness of resources, agonistic activity (i.e. dominance and aggression) and individual attributes (i.e. morphology and behaviour) in a group of captive mouflon males (Ovis ammon musimon). Feeding performance was analysed using linear mixed models based on predictors about patchiness of the resource, and behavioural and morphological indices. No clear relationship was found between dominance and feeding performance. However, the general pattern showed (i) a decrease in overall feeding performance with the dispersion of the resource; (ii) that the discrepancy in feeding performance among individuals was maximal when confronted with intermediate conditions; and (iii) that alternative tactics allowed subordinate individuals to achieve a similar feeding performance to dominants. The results of this study suggest that, over and above agonistic behaviour and dominance, the motivation of individuals and its variation over time, though difficult to evaluate, could be key to understanding the coexistence of alternative behavioural tactics.