Social ties drive post-fission group choice in blue monkeys

Permanent group fissions present rare opportunities for individuals in philopatric groups to select their groupmates. Studying post-fission group choice allows insights into how sociality influences animal decision-making and which social ties are important to group-living individuals. Our first analysis investigated which social ties influenced post-fission group choice in adult female blue monkeys by considering the strength and consistency of their ties with their original group’s members, as well as their dominance relations, relatedness to other female group members, and risk of infanticide. We used these dyadic and nodal characteristics in a separable temporal exponential random graph model to model edge persistence across two timesteps, before vs. after fission. Our second analysis used a conditional logit model to investigate the role of the original group’s resident male in a female’s post-fission group choice, assessing the strength of her tie to him and her vulnerability to i..., Observational data were collected from blue monkeys (Cercopithecus mitis stuhlmanni) in the Kakamega Forest, western Kenya surrounding five instances of group fission that occurred between 2008 and 2019. During the study period, trained observers monitored the different groups on a near daily basis, conducting focal animal samples on all adult females (classified as adults from the day they give birth to their first offspring). Focal animal samples were designed to last 30 min, and were retained in the dataset if they were at least 20 min long. On each day, females were chosen as subjects so that focal samples accumulated evenly across individuals and among different periods of the day (morning, midday, afternoon). Instantaneous recording of the focal subject’s behavior occurred at 1-minute intervals and included the identities of any social partners and individuals in proximity (within 1m). Agonistic interactions (with one individual showing submission) were recorded during focal sampl..., , # Social ties drive post-fission group choice in blue monkeys

[https://doi.org/10.5061/dryad.xd2547drj](https://doi.org/10.5061/dryad.xd2547drj)

Permanent group fissions present rare opportunities for individuals in philopatric groups to select their groupmates, and so by studying post-fission group choice, we can gain insight into how sociality influences decision-making. Our study investigated which social ties and individual attributes influence post-fission group choice in blue monkeys by considering the strength and consistency of female’s ties to social affiliates, her relatedness to female peers, her relative rank, her vulnerability to infanticide, and her tie with the original group’s resident male. We found that females maintained different kinds of relationships during fission (those with social affiliates and the original group’s resident male). Here we present two datasets (and associated R code) used in this analysis, one (Dataset 1) including attributes of dyadic ties an...,