Social tolerance plays a key role in shared leadership

Abstract

Shared leadership in consensus decision making has been observed in the collective movements of various mammalian species. While multiple social interactions influence this decision-making pattern, the link between social tolerance and the characteristics of collective movement remains underexplored. In this study, we propose a new ‘social tolerance’ hypothesis, suggesting that ‘social tolerance covaries with the level of shared leadership in collective movement’. We filmed 50 groups of Père David's deer, Elaphurus davidianus, by drone and collected collective movement characteristics and social tolerance characteristics on group and individual levels. Our findings revealed that (1) at the group level, tolerant groups showed higher levels of shared leadership, characterized by a higher proportion of leaders. Groups with higher proportions of females distributed leadership more evenly among their members. (2) At the individual level, females who formed more proximity interactions and males with higher dominance displayed higher leadership scores. Low-ranking females adopted an accelerated pace in recruiting followers, whereas none of the social tolerance characteristics in males correlated with followers' joining latency. In addition, females demonstrated a more equal distribution of shared leadership than males. These results may be due to differences in reproductive strategies between males and females. Although our work provides limited evidence for the ‘social tolerance’ hypothesis, we aimed to provide a deeper insight into the mechanisms by which social tolerance influences collective movements.