Anti-predatory vigilance and the limits to collective detection: visual and spatial separation between foragers

摘要: Collective detection concerns the idea that all members of a socially feeding group are alerted to an attack as long at least one member detects it. We found collective in mixed flocks emberizid sparrows is limited markedly by relatively small degrees visual and spatial separation between foragers. These limits on appear influence degree which flock lower their vigilance with increasing size (the effect). Specifically, decrease isolation foragers accompanied concomitant strength effect. Explanations for vigilance-related effects such based upon bird’s ability monitor behavior flockmates can be ruled out our experimental system. Our results also shed light issue whether effect influenced more or simple dilution risk size. argue not only important determinant effect, but phenomena interdependent.