The results in this study suggest that it is indeed possible to train dolphins to be called over, using both biologically and non-biologically relevant sounds.

Furthermore, the results suggest, in accordance with the hypothesis of this study, that discrimination between a dolphin's own, and others', signature whistles is more likely to be successful than discrimination between an assigned and other trivial sounds. 

The only male in this study was the one most successful in the discrimination task. Although not regularly documented for the sake of the study, he was also observed to increase his use of his signature whistle, both during and in connection to the sessions, as he progressed in his training.

Due to the small sample size in this study, we can, however, not say for sure that our results do not simply stem from individual differences in learning abilities of the trained dolphins. We therefore recommend further testing of the Whistle caller concept, and its applicability in the husbandry routines of dolphins under human care. 

We suggest that future studies focus on:

• Male-female differences in discrimination success when applying the Whistle caller concept
• How the characteristics of the trivial sounds affect discrimination success
• The option of calling over more than one animal at a time by sending out several signature whistles in succession