Behavioural and physiological responses of naïve European rabbits to predator odour

Animals show a variety of antipredator strategies in response to the presence of chemical cues from mammalian predators. Nevertheless, there is no general agreement as to whether recognition of predator odours is dependent upon experience. We conducted an experiment on European rabbits Oryctolagus cuniculus naïve to any contact with predators and we investigated (1) whether they possessed a mechanism for the recognition of the odour of a predator, and (2) how they responded behaviourally and physiologically to that odour. We used fox Vulpes vulpes faeces as the source of the predator odour and sheep Ovis aries faeces as a nonpredator control odour. The experiments were conducted in small outdoor enclosures where the animals were kept singly. We recorded patterns of vigilance, activity and feeding, and changes in glucocorticoids and body mass. The rabbits showed a clear antipredator response to the presence of fox faeces, whereas they behaved neutrally in response to sheep odour. The response consisted of increased avoidance and vigilance while feeding and more investigation before feeding. Furthermore, the rabbits showed a physiological alarm response, that is, an increased responsiveness of their adrenocortical system and weight loss. However, the total activity budget, measured as time spent outside the burrow, the time spent feeding, and the amount of food ingested remained largely stable during the experiment. We conclude that rabbits recognised predator odours and that this recognition was independent of experience.