A nutritionally-explicit test of the food-safety trade-off under predation risk

Predation risk elicits physiological and behavioural responses that enhance prey survival but can constrain foraging. Extensive evidence suggests that prey experience a food-safety trade-off whereby prioritizing safety reduces resource acquisition. However, predation risk also induces physiological stress responses, which increase nutritional demands needed to fuel antipredator responses. Thus, prey are expected to optimize macronutrient intakes towards higher carbohydrate diets while also seeking safety. To assess how predation risk shapes foraging behaviour and macronutrient intakes, we examined foraging choices of Psammophilus dorsalis in large semi-outdoor enclosures. We manipulated macronutrient composition of food [high vs. low CP (carbohydrate: protein)] and access to food options (near vs. far from refuge), and compared the responses of lizards under predation risk and control conditions. Lizards exposed to predation risk had higher (but non-significant) corticosterone levels, reduced activity, and generally foraged from sites near their refuge compared to control groups. Macronutrient ingested was marginally affected by the type and accessibility of food options, but retention of ingested elements shifted with exposure to predation risk. These results demonstrate that while the food-safety trade-off primarily governs foraging decisions under predation risk, nutritional needs may also play a role.