1. Functional diversification of contact calls contribute to the cohesion of a multi-level society.
- Author
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Yang, Yi-Jun, Yan, Ying, Fang, Gu, Song, Yu-Ting, Zang, Jing, Tian, Wen-Yong, Zhu, Dai-Bo, Garber, Paul A., Li, Bao-Guo, and Qi, Xiao-Guang
- Abstract
Golden snub-nosed monkeys (Rhinopithecus roxellana) live in multilevel societies of over 100 individuals. Despite exploiting low visibility high-altitude forests and home ranges of 14 km
2 , they maintain large and cohesive social networks that serve to coordinate travel and daily activities effectively. During traveling, foraging, and feeding, golden snub-nosed monkeys communicate using contact or coo calls. These contact calls are conspicuous (70–75 decibels), directional, and function to communicate affiliative intention, identity, and location. Based on social network analyses, we found that golden snub-nosed monkeys exchanged contact calls among individuals within their resident one-male multi-female unit (OMU) and with conspecifics from neighboring OMUs. Within each OMU, there were more frequent call exchanges among more spatially separated members than among closely located individuals. In the case of contact calls between OMUs, there were more frequent contact call exchanges among closely located leader males. These findings demonstrate that contact call exchanges communicate individual identity and location, promote social bonds, and contribute to OMU and inter-OMU coordinated behavior that is essential to a well-functioning multilevel or tiered social network. In addition, given that 34% of all contact call exchanges were initiated by adult males (twice the number given by adult females), male OMU leadership appears to play a critical role in coordinating activities, directing travel, and promoting group cohesion. Moreover, given that higher-ranking males initiated more contact call exchanges than lower-ranking males, higher-ranking males appear to play a more important role in leading and coordinating travel and the fission–fusion dynamics of this multilevel society. Significance statement: Primates living in a large multi-level society face significant challenges in coordinating group movement and promoting social cohesion. We found that golden snub-nosed monkeys use contact coo calls to regulate spatial proximity and social interactions within their resident one-male multi-female unit (OMU) and with neighboring OMUs. Adult males are the primary call-givers. Within OMUs, there were significantly more frequent call exchanges between more spatially separated members. In contrast, between OMUs, there were more frequent contact call exchanges between leader males, especially when they were in close spatial proximity. Contact calls, which are given at an average distance of 5-200 m, communicate information concerning caller identity, location, and intention. Given that more than 90% of contact call exchanges occurred during foraging and traveling, this call type is critical in coordinating activities and regulating fission-fusion dynamics in this large multi-level society. [ABSTRACT FROM AUTHOR]- Published
- 2024
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