Aging can induce changes in social behaviors among humans and nonhuman primates (NHPs). Therefore, investigating the aging process in primate species can provide valuable evidence regarding age-related concerns in humans. However, the link between aging and behavioral patterns in nonhuman primates remains poorly comprehended. To address this gap, the present research examined aging-related behaviors exhibited by Tibetan macaques (Macaca thibetana) in their natural habitat in Huangshan, China, during the period from October 2020 to June 2021. We collected behavioral data from 25 adult macaques using different data collection methods, including focal animal sampling and ad libitum sampling methods. We found that among adult female macaques, the frequency of being attacked decreased with their age, and that the frequency of approaching other monkeys also decreased as age increased. In males, however, this was not the case. Our findings demonstrate that older female macaques exhibit active conflict avoidance, potentially attributed to a reduction in the frequency of approaching conspecifics and a decreased likelihood of engaging in conflict behaviors. This study provides some important data for investigating aging in NHPs and confirms that Macaca can exhibit a preference for social partners under aging-related contexts similar to humans.

Sleeping-site selection is a critical decision-making process in animals, influenced by evolutionary pressures. However, the key factors controlling this choice under group demography, and how these vary seasonally, remain poorly understood. This study investigated the selection of arboreal versus terrestrial sleeping sites and the underlying decision-making processes in a free-ranging group of Tibetan macaques (Macaca thibetana) at Huangshan, China, across mating (July–January) and non-mating (February–April) seasons. Generally, Tibetan macaques slept arboreally during mating season (July–September), switched to terrestrial sites afterward (October–March), and returned to trees in the following April. As for the decision-making, females consistently played a central role, initiating collective movements to arboreal sites more frequently and attracting more followers during the mating season, and joining the collective movements earlier across all seasons. Decision-making rules also varied seasonally. Females and middle-aged/older individuals mainly initiated movements to arboreal sites during the mating season, whereas terrestrial movements were led primarily by older individuals, with high social centrality attracting more followers. In the non-mating season, no specific social traits predicted initiators across sleeping sites, though females consistently attracted more followers and joined movements earlier. In terrestrial movements specifically, older individuals joined later, whereas highly socially central individuals joined earlier. Our research reveals that the sleeping-site selection decisions of Tibetan macaques are influenced by their matrilineal group structure. This study provides insights into the ecological adaptability of primates, demonstrating how dynamic decision-making supports survival in seasonal environments among social animals.