Dominance style predicts differences in food retrieval strategies

In several species, rank predicts access to food, and subordinates may need specific behavioural strategies to get a share of resources. This may be especially important in despotic species, where resources are strongly biased in favour of dominants and subordinates may more strongly rely on specific tactics to maximize food intake. Here, we compared three macaque species with an experimental set-up reproducing feeding competition contest. Following our predictions, more tolerant species mostly retrieved food in the presence of others and were less dependent on specific tactics. Contrarily, subordinates in more despotic species more likely collected food (1) when dominants could not see food or (2) were attacking others, (3) while “dissimulating”, or (4) “storing food”. Our study reveals that dominance styles reliably predict the probability of using specific food retrieval tactics and provides important insights on the social conditions that might have led to the emergence of tactical deception.

Dominance style only partially predicts differences in neophobia and social tolerance over food in four macaque species

Primates live in complex social systems with social structures ranging from more to less despotic. In less despotic species, dominance might impose fewer constraints on social choices, tolerance is greater than in despotic species and subordinates may have little need to include novel food items in the diet (i.e. neophilia), as contest food competition is lower and resources more equally distributed across group members. Here, we used macaques as a model to assess whether different dominance styles predict differences in neophilia and social tolerance over food. We provided familiar and novel food to 4 groups of wild macaques (N = 131) with different dominance styles (Macaca fuscata, M. fascicularis, M. sylvanus, M. maura). Our study revealed inter- and intra-specific differences in individuals’ access to food, which only partially reflected the dominance styles of the study subjects. Contrary to our prediction, social tolerance over food was higher in more despotic species than in less despotic species. Individuals with a higher dominance rank and being better socially integrated (i.e. higher Eigenvector centrality) were more likely to retrieve food in all species, regardless of their dominance style. Partially in line with our predictions, less integrated individuals more likely overcame neophobia (as compared to more integrated ones), but only in species with more tolerance over food. Our study suggests that individual characteristics (e.g. social integration or personality) other than dominance rank may have a stronger effect on an individual’s access to resources.

Dominance Styles of Female and Male Barbary Macaques (Macaca Sylvanus)

Dominance styles can be understood as consequences of different competition regimes imposed by socio-ecological conditions. As vital resources differ for males and females of the same species, one might expect different competitive tactics, hence differential dominance styles in both sexes. This was investigated on the basis of dyadic competition over a food resource (peanut) or mating partner (estrous female) in the semifree ranging colony of Barbary macaques at 'Affenberg Salem'. Both, females and males competed over nuts. The dominant typically won the nut by eliciting the retreat of the subordinate with a ritualised assertive signal, the 'rounded-mouth threat face'. The competitive style in adult male dyads (AM-AM) differed from that of all other age-sex class combinations, including adult versus subadult males, and did not change with the kind of incentive: Use of threat faces and retreat was replaced by ignoring, tension, or recruitment behaviour, and in 115of AM-AM dyads at least one nut was taken by a third party. In the few cases where a male did perform a threat face his rival responded by counter aggression, recruitment or appeasement/affiliation, or by taking the nut nevertheless. It is concluded that (1) dominance relations among adult females are stricter than those between males, indicating different dominance styles for the two sexes; (2) the 'egalitarian' competitive style of adult males was compatible with an absence of formalisation of dominance-subordination relations and did not indicate an absence of competition among them; (3) Adult males behaved as dominance oriented as females if the risk of injury was small (as in AM-SM dyads). The 'egalitarian' behaviour in AM-AM dyads is best understood as the result of a stalemate where the risks of escalation are high relative to the value of the resource. In sum, the results suggest that variance in power asymmetries and differential cost-benefit ratios of escalated competition may produce different dominance styles even within the same species.