Social connectivity among female Tibetan macaques (Macaca thibetana) increases the speed of collective movements.

Abstract

Social network analysis provides insights into patterns of group movements in primates, but fewer studies to date have focused on the dynamics of how such movements occur. In this study, we proposed and tested two hypotheses about the influence of sex on social connectivity and group movement in Tibetan macaques (Macaca thibetana): (1) adult females are socially more connected than are adult males and (2) social connectivity facilitates the speed of collective decision-making. We collected data from 128 successful collective movements (≥ 2 individuals followed an initiator within 5min) over a 2-month period in a group of adult Tibetan macaques at Mt. Huangshan, China. Although high-ranking individuals of both sexes in our dataset were more central in their social network than were low-ranking individuals, our results show that affiliations between females were stronger, with more preferred associations than those between males. Groups with more females reached collective decisions faster than groups with fewer females. We conclude that female Tibetan macaques use their social networks to enhance the speed of collective decision-making, which may have associated fitness benefits.