Grouping promotes risk-taking in unfamiliar settings

Acting collectively in a group provides risk-reducing benefits. Yet individuals differ in how they take risks, with some being more willing than others to approach dangerous or unfamiliar settings. Therefore, individuals may need to adjust their behaviour when in groups, either as a result of perceiving greater safety or to coordinate collective responses, the latter of which may rely on within-group dynamics biased by group composition. In zebrafish we explored how these aspects of grouping affect risk-taking behaviour by comparing solitary to group conditions and testing the ability of group-member solitary responses to predict collective responses. We focused on approach-latency towards a novel object and an unusual food to test this, for shoals of five fish. There was no indication that collective latencies are predicted by how each fish responded when alone in terms of the extremes, the variance or the mean of group-member latency towards the unusual food and the novel-object. However, fish were overall faster and less variable in their approach when shoaling. This indicates lower risk aversion by individuals in groups, presumably as a result of group safety. An interesting consequence of the overall low risk-aversion in shoals is that more risk-aversive fish adjust their behaviour more than less risk averse fish.