Communication and Fission-Fusion Dynamics in White-Nosed Coatis

Abstract

There are both costs and benefits to group living. Benefits include an increased ability to find resources and reduced predation risk, while costs involve increased competition among group members for those resources. Some social groups manage these trade-offs through fission-fusion dynamics, where groups regularly split into subgroups (fission) and later merge back together (fusion). Understanding the factors that drive these events and the mechanisms group members use to navigate these processes can provide insights into the proximate and ultimate drivers of group living. In this thesis, I use white-nosed coatis as a study system to investigate the extent and nature of their fission-fusion dynamics and the role of vocal signalling during these processes. Coatis are an ideal species for studying these dynamics because they live in relatively stable social groups that frequently split into smaller foraging parties. However, the underlying drivers of fission and fusion events in coatis have remained poorly understood. By leveraging advanced tracking technologies, I simultaneously recorded the locations and vocalisations of all members of three wild white-nosed coati groups in Soberania National Park and on Barro Colorado Island, Panama. Utilising these data, I provide novel insights into the drivers of their fission-fusion dynamics and the factors that shape their collective decision-making. To determine the role of vocalisations in white-nosed coati collective behaviour, the first chapter characterises the diversity of calls in this species, describing the temporal and structural features of their vocalisations. I found that coatis have a rich vocal repertoire with calls that vary in frequency, duration, and order of emission. Additionally, there is variation in call rates between group members, potentially due to different levels of social influence within the group. In the second chapter, I characterise the extent of white-nosed coati fission-fusion dynamics and investigate the role of social and physiological factors in shaping their subgrouping behaviours. I found that individuals have consistent social preferences when deciding whom to split with, and these preferences are driven by relatedness rather than physiological factors such as age and sex. In the third chapter, I examine the fine-scale movements of group members during fissions and fusions to determine the mechanisms by which these events occur. Using new analytical tools, I characterise different fission and fusion types and demonstrate that incorporating vocalisations into these analyses provides a more comprehensive understanding of how these events unfold. I show that coatis use vocalisations to coordinate fission and fusion events and suggest that these events are driven by varying preferences for when to travel and foraging competition. This is the first study to use tracking technologies to explore how vocal communication influences group cohesion and coordination during fission and fusion events. I have demonstrated the wealth of information that can be obtained using this approach and provided a framework for investigating these processes that can be applied across diverse social and ecological contexts. My results offer new insights into the factors that shape decision-making processes, shedding light on the drivers of group living.