Prey behavioural reaction norms: response to threat predicts susceptibility to predation. (October 2017) - Toscano, Benjamin J.
Abstract : Behavioural syndromes (i.e. population-level behavioural correlations) arise when individuals, on average, maintain the same behavioural expression across different ecological contexts. Population-level syndromes can appear maladaptive, such as when prey remain active across the absence and presence of a sit-and-wait predator. Yet in nature, individuals often vary in syndrome adherence, exhibiting individual-level differences in behavioural plasticity. Here, I use an experiment to show that individual behavioural plasticity (a reduction in activity level in the presence of predation threat) increases a prey's likelihood of surviving predator exposure, and further predicts survival better than single-context activity level measures. In an additional experiment, I identify conditioning (nonlethal predator exposure) as a process that reduces prey activity level. This work demonstrates that although population-level behavioural syndromes can appear maladaptive, behavioural plasticity and conditioning could potentially ameliorate negative effects at the individual level. Highlights: Behavioural plasticity may allow prey to cope with natural gradients in predation risk. I examined effects of behavioural plasticity on crabs' likelihood of being preyed upon. Surviving crabs were more responsive to threat than were crabs that were eaten. Crabs conditioned to threat reduced risky behaviour over time. Plasticity and conditioning may offset negative population-level effects.