ABSTRACT
The cost-benefit of social behavior depends on group size and the social interaction. As group size increases, competition for resources increases, while individual vigilance may decrease due to the lower probability of individual predation or increased competition for resources. To test predictions of the "many eyes hypothesis" and the "competition hypothesis", we investigated the effects of social attributes on the vigilance, foraging, direct conflict and sex on social groups of ruddy ground-doves (Columbina talpacoti) in an urban area. We observed that the number of conspecifics did not influence individual foraging behavior, instead, the vigilance decreased as flock size increased. Moreover, the number of conflicts within the flock negatively affected individual vigilance. However, larger flocks exhibited more direct conflicts, and males were more frequently involved in social conflicts, regardless of the sex ratio of the flock. Finally, the investment in both vigilance and foraging was not influenced by the sex of the focal individual or the sex ratio of the flock. Our findings indicate that conspecific numbers and flock social organization significantly influence the cost-benefit dynamics of flocking behavior. Larger flocks enhance vigilance for predator detection but come at an individual cost due to increased resource competition and conflicts.
