Anti-Predatory Vigilance

Abstract

Anti-predatory vigilance allows prey to detect predators before it is too late to escape. Vigilance can be a state or a behavior. External markers of vigilance are not always sensitive or specific to the state of vigilance, which makes it difficult to document vigilance unambiguously. Vigilance research has focused mostly on functional hypotheses and neglected causation and development of vigilance. Drivers of vigilance include any social or environmental factor that has an impact on predation risk and food availability, and thus ultimately on anti-predatory vigilance. Of all the drivers of vigilance, group size has attracted the most attention. Models predict that vigilance decreases with group size through several mechanisms including the many-eyes effect (greater ability to detect predators in a group) and the dilution effect (reduction of individual risk due to the presence of alternative targets for the predator). Human-caused disturbances also alter perceived predation risk and can have an influence on vigilance. Recent research indicates that prey in groups pay attention to the vigilance of neighbors, which can lead to synchronization or coordination of vigilance at the group level.