Department of Physics, Chemistry and Biology (IFM)

Echolocation is considered an essential part of dolphin life, important for navigation, predator avoidance and foraging. However, this behaviour is not well stimulated in bottlenose dolphins under human care. The aim of this study was to introduce and evaluate the effect of two artificial environmental enrichment items; a sonar-controlled “meandering” hose and a box containing coral sand, on the behaviour and echolocation frequency of eight bottlenose dolphins at Kolmården Wildlife Park, Sweden. The hose could be set in three active states, two of them in which food items were ejected into the pool with the water flow, and a non-active state. The coral sand box was presented to the dolphins with and without food items buried in the sand. It was found that the dolphins performed exploratory and foraging behaviour towards both types of enrichment items. Both the time and the number of sonar clicks aimed at the “meandering” hose increased when the hose was in its active states compared to its non-active state, and the food items did not influence the echolocation frequency. The dolphins aimed sonar clicks towards the box and were capable of locating and retrieving food items from the box. It is unclear if they did so using echolocation. The tested environmental enrichment items seem to stimulate echolocation in bottlenose dolphins; however, further studies are needed to improve the enrichment value of the items before implementation in dolphinaria.