Diet cues alter the development of predator recognition templates in tadpoles

Abstract: Recognising predators accurately is key to making fine-scale adjustments to behaviour that enhance survival and maximise overall fitness for prey. Prey incorporate information from specific predator features in order to recognise predators and the risk they pose. For olfactory cues, prey can use both predator odour and diet cues to recognise predators. The role of diet cues in predator recognition has only been tested when they provide information about risk and act as an unconditioned stimulus. Thus, it is unclear whether prey use diet cues in the development of more general predator recognition templates. Here, we tested whether diet cues that contain no apparent information about the prey’s vulnerability to the predator are used by prey when they learn to recognise predators. We trained predator-naive wood frog tadpoles (Lithobates sylvaticus) to recognise the odour of a novel crayfish (Orconectes virilis) as risky by pairing tadpole alarm cues with the odour of crayfish fed one of two diets: alfalfa pellets or earthworms (Lumbricus sp.). We tested tadpoles from each group for their response to one of the two crayfish diet odour combinations or a water control. Tadpoles displayed antipredator responses to crayfish odour, irrespective of diet. However, their responses were stronger when tadpoles were exposed to crayfish fed the same diet as during training. Such results demonstrate that diet cues play a previously unrecognised but subtle role in predator recognition and suggest that flexibility in prey choice can lead to an advantage for the predator. Significance statement: Recognising predators and the threat they pose is critical for prey to adjust their behaviour in response to fluctuations in predation risk. There is therefore a need to understand how prey use different cues to develop effective recognition templates that allow for threat-sensitive adjustments to behaviour. Here, we demonstrate that diet cues of predators contribute to the development of predator recognition templates by prey. These results provide new information about how prey develop recognition templates for predators and that, by incorporating diet cues, they are able to adjust their responses to variable risk posed by different predators within a population. Additionally, we suggest that generalist diets may provide unrecognised benefits to predators when switching between prey types.