Do bottlenose dolphins display behavioural response to fish taste?
Résumé
The chemosensory abilities (i.e. taste, smell and trigeminal perception) of odontocete cetaceans are still widelyunknown. However, a better understanding of their potential use of these senses would not only improve ourknowledge of their behavioural ecology, but also allow us to develop behavioural enrichment strategies forcaptive odontocetes using sensory stimulation. While studies on taste bud anatomy and taste receptor genes inthese animals have provided useful information, ultimately behavioural experiments are crucial to assesswhether odontocetes use their sense of taste in water. Go/no go and conditioning experiments in bottlenosedolphins (Tursiops truncatus) have previously shown that they can perceive basic tastes, but it is still unclearwhether they are able to detect food-related chemical mixtures. We thus designed a spontaneous choiceexperiment using floating taste diffusers in order to test whether captive bottlenose dolphins could detect anddisplay attraction behaviours towards a natural fish taste stimulus. Four dolphins, two adult males and twojuvenile females, were involved in the experiment. Our results show that the juvenile females interacted with thefish taste diffuser significantly more than with the control. However, the adult males did not seem to make aclear choice. Also, the juvenile females showed a significantly greater level of motivation towards the test,spending more time interacting with the diffusers and holding them in their open mouth more often than theadult males. These findings corroborate previous behavioural studies suggesting that taste perception is functional in bottlenose dolphins, at least in young individuals. They also suggest that the taste of their natural prey could be attractive to them. Finally, the methodology used in this study proved to be easy to implement in captive odontocetes and will allow for investigating further their use of taste in feeding and social contexts without the need for conditioning experiments that require long periods of training. This experimental design could also be included in behavioural enrichment initiatives in captive marine mammals.