Individual behavior and survival: the roles of predator avoidance, foraging success, and vigilance

Variation in antipredation behavior should translate into variation in survival. Effective general defenses, such as predator avoidance, decrease the likelihood that an individual is attacked and should therefore reduce selection on behaviors that enhance probability of escape on attack. Escape behaviors become important if animals cannot avoid attack. We investigated the relative effects of avoidance and escape enhancing behaviors on the survival of juvenile redshanks, Tringa totanus, over 2 winters. We predicted that avoidance behavior should be the primary behavioral correlate of survival, but when forced, by starvation risk, into areas where risk of attack is much higher, behaviors that reduce risk of capture once attacked should also promote survival. We found that reducing exposure to attack was most important for increasing survival and that increased vigilance and foraging success rate only increased survival for individuals that spent more time in high-risk areas. Use of the high-risk area and survival varied between years, suggesting that variation in starvation risk (i.e., colder winters) may provide a mechanism for selection on capture-reducing antipredation behaviors to be maintained because predator avoidance, the most effective antipredation behavior, is not then possible.