Evaluation of classical music as an enrichment in bottlenose dolphin.

The purpose of the study was to evaluate if classical music may act as an enrichment for captive bottlenose dolphins (Tursiops truncatus). To this aim classical music provision was compared with that of a less complex auditory stimulus (rain-sound) and a visual enrichment (slideshow of photographs). The effect of the enrichments was evaluated by comparing the behaviour expressed by dolphins before the provision of the enrichment (pre-enrichment phase) with that expressed during its provision (enrichment phase). The subjects were five females and one male dolphin housed together in a dolphinarium in Riccione, Italy. All enrichments were novel to these subjects and each enrichment was provided for 20 minutes a day, on 7 days with a randomized schedule. Non-specific effect regarding all type of enrichment was observed on breathing behavior, which increased from 94,1 ± 3.6 events/hr (estimated marginal mean ± se) in the pre-enrichment phase to 98.7 ± 4.5 events/hr in the enrichment phase (p = 0.022, Generalized Estimating Equations model, (GEE)). Specific effects were only found for classical music, which resulted in an increase of two social affiliative behaviours from the pre-enrichment to the enrichment phase, namely synchronous swimming (8.9 ± 1.5% VS 16.4 ± 1.7% of observation time, p <0.001, sequential Bonferroni-corrected comparisons after GEE) and gentle touches (19.5 ± 3.3 VS 47.8 ± 9.2 events/hr, p < 0.001). The results indicate that presentation of classical music had a positive effect on dolphins’ social behavior, with promising capability to act as an effective environmental enrichment in this context. Even if the mechanism by which classical music exerts its effects and which specific acoustical properties are responsible for it are still unknown, the specificity of effects on social behavior suggest that classical music could be particularly useful when an enhancement in social behaviours is needed.