A Quantitative Assessment of Trainers-Dolphins' Interactions in the Absence of Food Reward.

All the studies that have considered the motivation of the dolphins to interact with their trainers as a possible welfare indicator have been carried out in facilities where the trainer-dolphin interactions (TDIs) sessions were reinforced with food. Therefore, in these specific circumstances, it was difficult to separate the motivation of the dolphins interacting with the trainers from the food drive. The current study aims to assess the interaction between the trainers and the dolphins in the absence of food rewards. The research was carried out at The Dolphin Reef (Eilat, Israel), a facility where the interaction between the trainers and 14 bottlenose dolphins of different sex and age classes did not involve food rewards. A total of 531 TDIs were recorded, with dolphins participating in 94.5% of the sessions and an average of three dolphins per session. The dolphins participated in a higher number and more frequently in the TDIs when toys were provided by the trainers. Diel and seasonal differences were also observed, with the dolphins participating more during the morning sessions and the neutral season. The latency of response of the dolphins to the presence of the trainers on the platform or in the water, whether or not advertised by the trainers' signal ("call" or "no-call"), was very short (usually less than 1 min), and the dolphins often anticipated the beginning of the sessions by arriving at the trainers' location before or upon the caretakers' arrival (96% of the time). Individual differences in the participation in the TDIs were also recorded, which might be linked to both the dolphin's health/welfare status or their personality. The current study shows that the separation of the TDIs from the food reward allows for a better understanding of the willingness of dolphins under human care to interact with their trainers. In addition, the results presented in this paper show that such TDIs are an important part of these dolphins' lives, which suggests that these interactions might be an additional tool to improve the animals' social environment and monitor their welfare.