Persistent individual differences in tactic use in a producer–scrounger game are group dependent

Abstract

Consistent individual differences in behaviour have now been documented in a broad range of organisms over a variety of contexts. However, individual differences in social contexts have received less attention. We explored the consistency and temporal persistence of individual differences in tactic use in a producer–scrounger foraging game using two sets of flocks of wild-caught nutmeg mannikins, Lonchura punctulata. With both sets of birds, we observed significant individual differences in tactic use that persisted under different food distributions and when flock members were reunited at a 6-month interval with the same flockmates but not when flock members were different. In another experiment, in which birds with high-scrounging profiles were made to forage in the same flock, the corporate frequency of scrounging was no higher, and the intake rate no lower than in flocks made up of intermediate- or low-frequency scroungers. Taken together our experiments suggest that persistent individual differences can arise from dynamics that are peculiar to the group in which they occur, underlining the importance of companions’ identity in determining tactic use in this game. Behavioural plasticity can erase idiosyncratic individual differences in games with frequency-dependent payoffs when group composition changes.