Supportive and tolerant relationships among male Tibetan macaques at Huangshan, China

Tibetan macaque males at Huangshan (Macaca thibetana huangshanensis) display highly skewed mating success and highly asymmetric patterns of aggression, but also high levels of tolerance. We examined affiliation, tolerance and agonistic support to test the hypothesis that increased tolerance in otherwise despotic males may occur when high-ranking males require support from other males to prevent (1) potentially destabilizing revolutionary coalitions against them, or (2) young adult males from usurping the alpha position. Several predictions of the first hypothesis were supported: Support was unrelated to kinship or affiliation and was generally conservative, serving to reinforce the current hierarchy. Nevertheless revolutionary coalitions posed a threat, particularly to alpha males. High-ranking males displayed tolerance in the form of co-feeding toward lower ranking males that supported them, and alpha males showed the most cooperation with the males that targeted them in revolutionary coalitions. Predictions of the second hypothesis were not consistently supported; male coalitions targeted young potential usurpers of the alpha position during only one of two periods of hierarchical stability. We suggest that high ranking males discourage revolutionary alliances by using two strategies. They primarily rely on conservative alliances, but also offer tolerance in cases in which conservative coalitions are less effective.