Effects of historically familiar and novel predator odours on the physiology of an introduced prey

Predator odours can elicit fear responses in prey and predator odour recognition is generally associated with physiological responses. Prey species are often more likely to respond to the odour of familiar rather than alien predators. However, predator naïvety in an introduced prey species has rarely been investigated. We examined the physiological response, as shown by changes in ventilatory variables, of an introduced terrestrial herbivore, the European rabbit Oryctolagus cuniculus, in Australia, to the odour of potential predators and to control odours (distilled water and horse), to explore if responses were limited to historical (cat and fox) predators, or extended to historically novel predators (snake and quoll). All odours except distilled water elicited a response, with rabbits showing long-term higher respiratory frequencies and lower tidal volumes after introduction of the odours, indicating an increase in alertness. However, the intensity of the rabbits’ reaction could not be directly linked to any pattern of response with respect to the history of predator-prey relationships. Rabbits exhibited significantly stronger reactions in response to both cat and quoll odours than they did to distilled water, but responses to horse, fox and snake odour were similar to that of water. Our results show that the introduced rabbit can respond to both historical and novel predators in Australia, and suggest that shared evolutionary history is not necessarily a prerequisite to predator odour recognition [Current Zoology 62 (1) : – , 2016 ].