Personality constraints versus flexible antipredation behaviors: how important is boldness in risk management of redshanks (Tringa totanus) foraging in a natural system?

Although the occurrence of individuals' behavioral differences in a "shyness-boldness" continuum (i.e., animals' propensity to take risks) is well established from experimental studies, little is known about how this personality trait might influence individual predation risk management decisions in natural systems. We recorded the risk management strategies (RMS) of a natural population of redshanks by observing the daily behavioral decisions made by foraging individuals. These included proximity to neighbors, flock size, position with respect to predator concealing cover, and vigilance. Using hierarchical mixed effects models, we found that although variation in most of these RMS had a significant individual component, only vigilance was moderately repeatable and therefore a personality trait. There was no evidence for a behavioral risk management syndrome: there were no significant correlations of vigilance with aggressiveness or exploratory behavior. Vigilance levels were highly flexible, were adjusted to the riskiness of the situation, and individuals varied in the degree of this plasticity, suggesting that a redshank's boldness (personality) may only contribute a small amount to natural risk management and that it is situation dependent. This emphasizes that although variable risk and profitability in the environment may select for different personalities (e.g., that determine baseline levels of vigilance all things being equal), these baseline levels can be modified greatly through behavioral flexibility when individuals are confronted by a change in environmental context, potentially removing these differences.