Interpositions in conflicts between males in bimale groups of mountain gorillas.

In bimale groups of mountain gorillas, conflicts between the silverbacks sometimes induce infants and females to interpose between the opponents. This paper describes a set of 40 such interpositions, using data from 380 h of focal observation of the silverbacks in 2 groups at the Karisoke Research Center. Aggressive interactions between males can be disruptive for females and infants: they might prevent them from feeding and resting normally. Interpositions occurred in 10-25% of the conflicts between silverbacks. None of the males seemed to receive a greater proportion of interpositions. Interpositions increased the interval between conflicts in one of the research groups. As a mechanism for resolving conflicts, interpositions could be advantageous when control interventions are not possible, i.e. when the individuals in conflict are the most dominant of the group. Because they might reduce the rate of aggression between males, these interpositions could also be one of the mechanisms allowing male coexistence in gorillas.