Investigating the Effect of Flock Size on Vigilance in the American Coot (Fulica americana) in Relationship to Habitat

Abstract

Among many anti-predator behaviors, vigilance is observed in many species and plays an important role in survival. In this study, we investigated the effect of flock size on vigilance in American Coots (Fulica americana)foraging on land and water, by observing individual birds in these habitats and recording the time spent scanning (i.e., vigilance). Mean flock size was larger on land compared to water and vigilance negatively correlated with flock size. Birds in water were more vigilant compared to on land, regardless of whether they were foraging alone or in flocks. However, the effect of flock size on vigilance showed a weak linear correlation as it was possible that other factors (e.g., human habituation, food kleptoparasitism, or scramble competition) could have also played a role in shaping vigilance. These results suggest that there is a relationship between flock size and vigilance, which are related to previous researches that show a negative correlation between vigilance and flock size. KEYWORDS: Birds; American Coot; Vigilance; Scanning; Foraging; Flock Size; Habituation; Competition; Behavior