Individual determinants of social foraging tactic use when resources are defendable: An experiment with zebra finches

In a social foraging context where individuals can search either for food (i.e. produce) or for opportunities to join (i.e. scrounge), bold individuals, generally, tend to produce more than shy individuals. Yet, the underlying cause of this link remains poorly understood. In particular, bold individuals might rely more on the producer tactic because they have less chance to detect joining opportunities compared to shy individuals or because they prefer more risky and uncertain behavioural tactics. To assess the importance of both mechanisms, we conducted a laboratory experiment with zebra finches (Taenyopigia guttata) that were observed while searching for defendable food patches using either the producer or the scrounger tactic, when their arrival order on the grid was either free or imposed by the experimenter. As anticipated, we detected a strong effect of neophobia on producer-scrounger tactic use, but contrary to most previous experiments in which food patches were not defendable, shy individuals, in the present study, relied more on the producer tactic. In addition, we found that arrival order had no significant effect on foraging tactic use in bold and shy individuals. Thus, our results support the hypothesis that producer-scrounger tactic use would not be determined by the ability of individuals to detect scrounging opportunities, but rather by their tolerance to uncertainty and risk. Furthermore, our findings have important evolutionary implications as they suggest that temporal and/or spatial heterogeneity in resource distribution, through influencing the success of each behavioural type, would contribute in maintaining personality differences within populations.