Training bottlenose dolphins to overcome avoidance of environmental enrichment objects in order to stimulate play activities.

Enrichment programs may contribute to the quality of life and stress reduction in bottlenose dolphins (Tursiops truncatus) kept in zoos and aquaria. The results of these programs are generally positive in terms of welfare, but the magnitude of their effects may vary greatly between individuals of the same species, especially when the enrichment plans are based on the introduction of manipulative objects. Some animals will interact spontaneously with novel objects, even without food rewards and in the absence of the trainers, while others show no interest or even aversion toward the objects. To determine if formal training can improve these conditions, we measured the effects of an operant conditioning program in the manipulation of objects by dolphins that initially avoided them. This program took place between April and October 2013 at Zoomarine Portugal. Subjects were two female and two male bottlenose dolphins (adults with ages from 17 to 35 years) that after a preliminary analysis showed avoidance or low interest in the manipulation of various toys. The level of interaction with introduced enrichment objects was observed before and after formal training to explore the toys (sixteen 20-min observation sessions per animal "before" and "after training"). In all subjects, an index of interest in object manipulation, in the absence of trainers, increased significantly after the application of the training techniques. The results show that an initial reinforcement program focused on the manipulation of toys may overcome resistance, improving the effects of environmental enrichment plans, and it is a potentially useful strategy to increase the welfare of some captive animals. Zoo Biol. 35:210-215, 2016. © 2016 Wiley Periodicals, Inc.