Underwater Mirror Exposure to Free-Ranging Naïve Atlantic Spotted Dolphins (Stenella frontalis) in the Bahamas

Abstract

The “mirror state,” described for human self-recognition, has been found in captive or human-raised species. In marine mammals, bottlenose dolphins and killer whales have shown evidence of body examination, self-directed and contingency checking behaviors whereas false killer whales appeared ambiguous and California sea lions did not recognize themselves in a mirror. Self-recognition processes in wild cetaceans remain unknown. Since 1985, a resident community of Atlantic spotted dolphin (Stenella frontalis) has been studied underwater in the Bahamas. We describe the reaction of free-ranging dolphins during 14 exposures to the presence of a mirror from 1994/1995 and 2004/2005. Responses to the mirror were mixed. Initial reactions of mother/calf groups were to swim around mirror and stay in close physical proximity. Others ignored the mirror entirely, or swam around or underneath. A single male became stationary and postured in an aggressive stance in front of the mirror. The wild spotted dolphins showed a significant preference to exposing and/or orienting their right side to the mirror versus their left side. We suggest that the animals assign different meanings to a mirror in the wild versus the same object in captivity.