Peers over the past: prior predation-risk experience does not dictate antipredator responses of individuals in groups.

Abstract

Animals can use predation-risk experiences to modulate their antipredator responses and improve survival under future risk conditions, a phenomenon known as behavioural carryover. However, different contexts, such as group living, may alter both risks and associated responses for an individual. A group can provide multiple antipredator benefits, including dilution and confusion effects, potentially modifying the payoffs of behavioural carryover. Despite the prevalence of both antipredator strategies, we know little about how group living and behavioural carryover interact. We tested the influence of group living on the behavioural carryover of predation-risk experience in Aedes aegypti. Previous work showed that predation-risk experience shapes future behaviour when individuals are solitary. We hypothesized that these carryover effects would become redundant in groups due to the protective benefits of group living. To test this, we compared the behaviour of risk-experienced and naive individuals in groups, both in the presence and absence of an immediate threat, and contrasted it with that of solitary individuals. As expected, past predation-risk experience did not influence behaviour in a group. Surprisingly, both experienced and naive individuals altered their behaviour in response to an immediate threat. These results suggest that predation-risk experience is more relevant when prey are solitary than in groups.