Social and ecological drivers of behavioural diversity in wild Costa Rican capuchins

The extent of behavioural diversity versus synchrony exhibited among
members of the same social group impacts group cohesion. Understanding
social and environmental drivers of behavioural diversity has implications
for understanding the evolution of group living and has been an enduring
goal of biologists. Here we analyse a 15 years behavioural dataset from
wild habituated capuchin monkeys to explore social and environmental
drivers of behavioural diversity. Between 2007-2022, instantaneous scan
samples were recorded every 30 minutes from 214 individuals across 8
social groups, ranging in size from 7-35 individuals. We examine social,
ecological, and demographic predictors of behavioural diversity at the
group and individual level, with a focus on the impact of group size. We
find that the behavioural richness and diversity of behaviours were
greater in large groups compared to small and medium-sized groups, that
individuals in small groups exhibited higher diversity across the day
compared to individuals in medium and large groups, and that daily maximum
temperature and rainfall were associated with decreased behavioural
diversity at the group level. Overall, group size appears to impact
important aspects of behavioural diversity within a group and among
individuals in this socially complex species. The breakdown in behavioural
synchrony of large groups likely influences movement ecology and social
relationships and may contribute to fission events that occur at upper
limits of group size. In the present study, we leverage a large dataset to
provide new insights into how social and environmental variables can
influence behavioural dynamics in an intelligent, social mammal.