-For the young of many species, social play is an important aspect of development. Previous research has shown that bottlenose dolphin calves engage in social play early in life. Despite these observations, little is known about the development of social play in this species. The present study examined the social play behavior of three aquarium-housed bottlenose dolphin calves during their first year of life. We were particularly interested in the partner with whom each calf played as well as the initiator of social play bouts. Each calf was observed from birth until the end of its first year and all bouts of social and solitary play were recorded during observation sessions. While the calves engaged in both social and solitary play throughout their first year, play became increasingly social as they aged. The calves also became more likely to initiate social play interactions with increasing age. A calf's first social play partner was typically its mother, but other calves quickly replaced the mother as the most common play partner. When it came to play partner preferences, we found that calves of similar age were preferred as play partners, but age similarity became less characteristic of play partners as the calves grew older. These findings likely reflect changes in the developmental competence of each of the calves individually, and support the notion that calves use social play to challenge themselves.
Keywords -Social play, Bottlenose dolphins; Development; Play partner preference; Tursiops truncatusSocial play, or play behavior directed at conspecifics (Burghardt, 2005), is evident in a variety of species and is especially salient in those with complex social structures. Social play has been reported in both human (e.g., Doyle, Connolly, & Rivest, 1980;Eckerman, Whatley, & Kutz, 1975;Fry, 2005) and non-human primates (e.g., Cordoni & Palagi, 2011;Harlow & Harlow, 1962;Hoff, Nadler, & Maple, 1981;de Oliveira, Ruiz-Miranda, Kleiman, & Beck, 2003), as well as a variety of terrestrial mammals (e.g., Byers, 1977;Drea, Hawk, & Glickman, 1996;Henry & Herrero, 1974;Lee, 1987;Wemmer & Fleming, 1974), aquatic mammals (e.g., Blomqvist, Mello, & Amundin, 2005Essapian, 1953;Gentry, 1974;Kuczaj, Makecha, Trone, Paulos, & Ramos, 2006;Mann & Smuts, 1999;McBride & Hebb, 1948;Renouf & Lawson, 1986; Spinelli, Nascimento, & Yamamato, 2002;Sylvestre, 1985), birds (e.g., Diamond & Bond, 2003; Pozis-Francios, Zahavi, & Zahavi, 2004), and even reptiles (e.g., Burghardt, 1998). The ubiquitous presence of social play in highly social species highlights the need for studies aimed at understanding the various aspects of this behavior and the role it plays in social interactions.One aquatic species in which social play is evident, but little studied, is the bottlenose dolphin,