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Predator-induced changes in the boldness of naïve field crickets, Gryllus integer, depends on behavioural type

Niemelä, Petri T., DiRienzo, Nicholas, Hedrick, Ann V.
Animal behaviour 2012 v.84 no.1 pp. 129-135
Gryllus, aggression, behavior change, freezing, predation, risk
In recent years, using a personality approach for studies of animal behaviour has increased our ability to predict an individual's or population's behavioural responses to external stimuli. At a population level, different behavioural types (e.g. bold and shy) often exist, and the behaviour of different types may not be free to vary across different situations. In the present study, we examined whether a predator introduction induced shifts in boldness and if predator-induced changes in behaviour depended on the individual's original behavioural type in the field cricket Gryllus integer. We also studied whether exposure to a natural predator affected the formation of a behavioural syndrome between aggression and boldness or the consistency of boldness. We define a behavioural syndrome as an association between functionally different behaviours or consistency in a behaviour over time or contexts. We found that exposure to a predator affected behavioural antipredator responses, measured as the time to recover from freezing (immobility). Moreover, we found that the different behavioural types expressed different behavioural responses to predator introduction (i.e. shy individuals became bolder and bold individuals more shy). However, an aggressiveness–boldness behavioural syndrome was not detected in either the treatment or control groups, and early antipredator responses were rank order repeatable only in the control group. We suggest that individuals' behavioural antipredator responses under increased predation risk depend on the individual's original behavioural type and that increased risk may break apart the consistency of behaviour.