1Animal Behavior Graduate Group, University of California Davis, 2Population Health & Reproduction, University of California Davis, 3California National Primate Research Center, University of California Davis, 4Anthropology, University of California Davis, 5Anthropology, University of Notre Dame, 6, Gibraltar Ornithological and Natural History Society
April 14, 2016 , Atrium Ballroom A/B
Social network topology provides insight to the structure of a group, but deciding which networks represent important components of group dynamics is a challenge. Dominance relationships can be represented by aggressive interactions or formal status signaling which may consist of signals of subordination or dominance. We investigated the structure of these networks in two groups of Barbary macaques from the Upper Rock Nature Reserve in Gibraltar. Focal sampling was used to record all occurrences of aggression and signaling of 35 adult individuals over two months. A Beta Random Field Percolation and Conductance method was used to calculate dominance probability of dyads using direct and indirect pathways in an aggression network. In addition, directional transitivity of aggression, unidirectional chatter (a bared teeth display associated with submission and affiliation), and round-mouth threat (RMT; associated with dominance) networks were calculated. Dominance probabilities show that rank was not completely linear, but rather consisted of tiers in the rank order such that individuals within the same tier had more ambiguity. Further, both groups’ RMT networks had perfect or near perfect transitivity (100% and 97.14%), greater than a network of unidirectional chattering (78.67% and 71.62%) and aggression (62.84% and 58.44%). The transitivity of RMT networks supports its previous classification as a status signal and its potential to represent dominance structure. Together, sections of uncertainty in a rank ordering of individuals and sparse hierarchical organization of signaling networks provide quantitative and qualitative evidence of non-linear dominance structure in these groups, supporting previous claims about this species’ hierarchies.