Fear generalization: correlated individual differences in response to predator cues, smoke and pesticides

Organisms face numerous biotic and abiotic threats. Behavioural responses to these threats impact individual fitness and often affect population, community and ecosystem outcomes. Although animals face diverse threats, most studies on behavioural responses to danger have focused on responses to either predators or humans. Relatively few have tested for consistent individual differences (CIDs) in response to other common threats (e.g. pathogens, chemical stressors, fire). If behavioural responses to different threats are correlated (i.e. if individuals exhibit fear generalization), this could connect disparate sources of mortality otherwise treated as separate. Despite its potential significance, no studies to date have examined fear generalization in ecological contexts. Here, we assayed behavioural responses of wolf spiders (Schizocosa maxima) to cues associated with predation, fire and pesticide. We provide the first study to quantify CIDs in response to smoke and one of few to document CIDs in response to pesticide. We then document among-individual correlations in behavioural responses to these threats; i.e. fear generalization. We found evidence for across-threat correlations in both the magnitude of response and the type of response (e.g. flee or freeze). These novel results have important implications for the ecological consequences of animal behaviour in the Anthropocene.