Environmental changes and anthropogenic factors modulate social play in captive bottlenose dolphins (Tursiops truncatus).

Social play varies among species and individuals and changes in frequency and duration during ontogeny. This type of play is modulated by environmental changes (e.g., resource availability). In captivity, cetaceans and their environment are managed by humans, and training sessions and/or public presentations punctuate the day as well as other frequent or occasional events. There is a lack of research on the effects of environmental events that occur in captivity and might affect dolphins' behavior. We studied the context in which nine bottlenose dolphins (Tursiops truncatus) played socially and the events that could potentially impact this social interaction. The dolphins' social play behavior was significantly more frequent and lasted longer in the morning than in the afternoon and was present before and after interactions with their trainers with a non-significant tendency to be more frequent before and after a training session than a public presentation. In an experimental paradigm using familiar environmental enrichment, our results demonstrated that environmental enrichment tended to increase social play duration whereas temporary noisy construction work around the pool and display of agonistic behaviors by members of the group significantly decreased it. These results contribute to better understand the social play distribution in captive bottlenose dolphins and the impact of different events within their daily lives. Since play decreases or disappears when animals are facing unfavorable conditions, the evaluation of social play may relate to the animals' current well-being. We suggest that social play has potential to become an indicator of bottlenose dolphins' current welfare state.