Collective decision-making in nocturnal huddling sleep: The influence of social factors on fans and fandom in Tibetan macaques

Abstract

Social animals frequently exhibit huddling sleep behaviors in response to nocturnal ecological pressures. However, there remain significant gaps in our understanding of the decision-making process promoting huddle sleep. Exploring how such decision-making processes are initiated and programmed in nonhuman primates offers additional insights into various animals, with a particular focus on humans. The present research examined the social factors and individual influences involved in initiating huddle sleep among a population of wild Tibetan macaques (Macaca thibetana) at Mt. Huangshan in Anhui, China. The results showed that social rank, age, and social centrality were involved in the decision-making process for huddle sleep. Individuals with higher rank and greater social centrality not only tended to act as leaders but also frequently took on followers. Younger individuals were more inclined to be followers. If an individual consistently followed a specific member during huddles, we referred to her/him as a fan. Individuals with more fans (fandom) and those that were consistently fans of others were also more socially central in their group. Such different selection factors fostered coordination among individuals and promoted huddle formation. The study has enhanced our understanding of nocturnal huddling behavior in social nonhuman primates and the intricate mechanisms involved in decision-making. The findings provide valuable insights into the sleep behavior of wild animals, thereby increasing our understanding of how monkeys maintain long-term survival. The analysis of sleep behavior has significant theoretical and practical implications for the conservation of Tibetan macaques.

Keywords

• Tibetan macaque
• Nocturnal huddling sleep
• Collective behavior
• Leader-follower dynamics