Bubbleblow in beluga whales (Delphinapterus leucas): a play activity?

In Odontocetes, bubbleblow is reported in several ethograms but its function is poorly understood. For the five captive beluga whales (Delphinapterus leucas) of the Vancouver Public Aquarium, we recorded the occurrence of this behaviour, its diurnal pattern and individual variability. We suggest that bubbleblow can be considered as a solitary play activity.