TitleThe effect of group size on vigilance in Ruddy Turnstones Arenaria interpres varies with foraging habitat
Publication TypeJournal Article
Year of Publication2013
AuthorsFuller RA, Bearhop S, Metcalfe NB, Piersma T
Date PublishedApr
Type of ArticleArticle
ISBN Number0019-1019
Accession NumberBIOSIS:PREV201300310150
Keywords07002, Behavioral biology - General and comparative behavior, 07003,, 07502, Ecology: environmental, 07508, Ecology: environmental biology -, Animal, Animals, Birds, Chordates,, applied and field techniques, Aves, Vertebrata, Chordata, Animalia, Behavior, Behavioral biology - Animal behavior, biology - General and methods, Charadriiformes [85518], field setting, flock density, species habitat type, intake rate affect, vigilance size,, interpres, Nonhuman Vertebrates, Vertebrates, predation risk, foraging habitat, predator attack, vigilance behavior,, ruddy turnstone], Terrestrial Ecology (Ecology, Environmental Sciences), vigilance contribution, [Arenaria
AbstractForaging birds can manage time spent vigilant for predators by forming groups of various sizes. However, group size alone will not always reliably determine the optimal level of vigilance. For example, variation in predation risk or food quality between patches may also be influential. In a field setting, we assessed how simultaneous variation in predation risk and intake rate affects the relationship between vigilance and group size in foraging Ruddy Turnstones Arenaria interpres. We compared vigilance, measured as the number of head-ups' per unit time, in habitat types that differed greatly in prey energy content and proximity to cover from which predators could launch surprise attacks. Habitats closer to predator cover provided foragers with much higher potential net energy intake rates than habitats further from cover. Foragers formed larger and denser flocks on habitats closer to cover. Individual vigilance of foragers in all habitats declined with increasing flock size and increased with flock density. However, vigilance by foragers on habitats closer to cover was always higher for a given flock size than vigilance by foragers on habitats further from cover, and habitat remained an important predictor of vigilance in models including a range of potential confounding variables. Our results suggest that foraging Ruddy Turnstones can simultaneously assess information on group size and the general likelihood of predator attack when determining their vigilance contribution.