Abstract
It is well established that living in groups helps animals avoid predation and locate resources, but maintaining a group requires collective coordination, which can be difficult when individuals differ from one another. Personality variation (consistent behavioural differences within a population) is already known to be important in group interactions. Growing evidence suggests that individuals also differ in their consistency, i.e. differing in how variable they are over time, and theoretical models predict that this consistency can be beneficial in social contexts. We used three-spined sticklebacks (Gasterosteus aculeatus) to test whether the consistency in, as well as average levels of, risk taking behaviour (i.e. boldness) when individuals were tested alone affects social interactions when fish were retested in groups of 2 and 4. Behavioural consistency, independently of average levels of risk-taking, can be advantageous: more consistent individuals showed higher rates of initiating group movements as leaders, more behavioural coordination by joining others as followers, and greater food consumption. Our results have implications for both group decision making, as groups composed of consistent individuals are more cohesive, and personality traits, as social interactions can have functional consequences for consistency in behaviour and hence the evolution of personality variation.