Age-related shifts in leadership patterns during group movements of Tibetan macaques: evidence from a long-term dataset

Collective movement is fundamental in animal societies, yet how the drivers of leadership roles change across an individual’s lifespan remains poorly understood. In particular, the combined effects of age and social factors on movement initiation lack investigation over biologically meaningful timescales, as most prior studies are limited to short-term observations. We analyzed a longitudinal dataset (2012–2023) from a group of free-ranging Tibetan macaques ( Macaca thibetana ) in Huangshan, China. Using analysis of variance, correlation analysis, and generalized additive models, we examined how age, social rank, and social relationships influenced movement initiation. Females initiated group movements more frequently than males. The tendency of females to act as initiators followed a unimodal distribution across age groups, increasing from youth to midlife before declining in older adults. Among old females (≥ 15 years), initiation rates correlated negatively with age, whereas male initiation patterns remained stable with age. In these aging females, higher social rank and greater centrality in proximity-based social networks were key predictors of successful initiation. Our long-term dataset reveals that leadership dynamics in collective movement, particularly among females, are governed by the interplay of age, social status, and social connectivity, highlighting how aging factors delicately shape decision-making processes in group-living animals.