When to mob? plasticity of antipredator behavior in common ravens' families (Corvus corax) across offspring development.

The ability to respond appropriately to predators is essential for survival. Because response options vary with predation context, anti-predator behavior is often flexible, context dependent and shaped by learning. Corvids engage in predator mobbing, which contains a vocal component (scolding) and predator-directed behaviors (approaches, attacks). Individuals typically gang up for mobbing and pass on information about predators; yet their expression of antipredator behavior is influenced by factors such as social status, age, and rearing conditions. Here we investigated the development of antipredator behavior in ravens, specifically the onset of mobbing and the extent to which these responses are affected by parental agitation. We exposed 12 captive families to a potentially dangerous human (DH) at two stages of offspring development: shortly after fledging and near independence. We tested the hypotheses that (i) parents are more protective when the offspring are young and that (ii) offspring show more predator-directed behaviors with increasing age. We found that (i) adults mobbed significantly more during the early test period and (ii) offspring were less likely to ignore the DH and showed increased engagement during the late test period. These findings suggest that parental anti-predator investment diminishes as offspring develop greater motoric and cognitive abilities. This reduced investment may encourage offspring to independently assess and respond to threats. Yet, they hardly engage in mobbing while they are with their parents. Future studies may clarify if the increase in offsprings' interindividual variance in both mobbing components are indicative for the emergence of individuality.