Observations of flipper rubbing in mother–calf pairs of captive bottlenose dolphins ( Tursiops truncatus ) suggest a body-surface care function

Bottlenose dolphins perform flipper rubbing in which they rub their partners with their pectoral fins. Considered similar to social grooming in primates, which have social and hygienic functions, flipper rubbing has been suggested to possess certain social functions. However, there are no reports based on quantitative data to support a hygienic function of this behavior. In this study, flipper rubbing and self-rubbing were observed in a group of three captive mother–calf dolphin pairs. In 19.2% of the observed 806 flipper-to-body rubbings and 54% of the 276 self-rubbings, dead skin was shed from the rubbed body part. There was a significant negative correlation between the number of flipper-to-body rubbing episodes the subjects received and their performance of self-rubbing. These results suggest that a function of flipper rubbing is to maintain and care for the body surface. In all mother–calf pairs, the mother rubbed her calf significantly more often than the calf rubbed the mother. Furthermore, each mother became a rubber significantly more often when their own offspring was their rubbing partner than when the partner was any other individual. These findings suggest that flipper rubbing is a mother-to-calf caring behavior.