Solitary, observer, parallel, and social object play in the bottlenose dolphin (Tursiops truncatus).

Many comparative studies have focused on the emergence of solitary and social play in early development, however, few consider observer and parallel forms of play. In this study, we analyzed approximately 21 h of video recordings and revealed a significant difference between the frequency of solitary, observer, parallel, and social object play states, in calf, juvenile, subadult, and adult bottlenose dolphins (Tursiops truncatus). While juveniles engaged in solitary play significantly more than other age groups, both juveniles and calves engaged in observer and social play significantly more than adults and subadults. Within their own age group, calves, juveniles, and subadults all showed a significant preference for solitary play. Calves preferred juvenile partners, while juveniles preferred calves during social play and other juveniles during observer play. Calves and juveniles preferred non-kin partners, especially during observer play. Together, these results have implications for social learning and behavioral transmission through observational play. With this knowledge, we can provide the appropriate social environment to dolphins in managed care with limited or constrained social availability, increasing learning opportunities and developmental outcomes.