Evidence for Facilitation of Horizontal Social Learning Among Social Subgroups of Juvenile Atlantic Spotted Dolphins (Stenella frontalis).

Although vertical (mother-to-offspring) information transfer has been reported in dolphins, it is unclear whether horizontal information transfer takes place between peers of non-parental individuals. We hypothesized that horizontal information transmission takes place within juvenile social play-forage subgroups and within pairs of juveniles in the form of social learning, as a way for older juveniles to contribute to the further development of younger juveniles’ foraging skills. Since 1985, a long-term study in the Bahamas has involved the collection of underwater videos and sound recordings on the social structure of a resident community of free-ranging Atlantic spotted dolphins Stenella frontalis. Foraging behaviors of juvenile dolphins were analyzed in 24 independent foraging events recorded on video from 1994 to 2013. Forty-nine juveniles in total were observed, including eight individually identified juveniles foraging alone, eight individually identified juveniles foraging in pairs, and 33 juveniles foraging in eight subgroups of three or more dolphins. The comparison of older juveniles' behavior against younger juveniles' behavior in juvenile play-forage subgroups suggested the potential for horizontal transmission of information about prey location. However, we found no direct evidence for social learning or of teaching in pairs. This new information about wild Atlantic spotted dolphin social structure is a starting point in horizontal information transmission research and is important in terms of cognitive processes and welfare implications.