Abstract: Interspecific interactions have been observed in a variety of social animals. Functional explanations include foraging, anti-predatory, and social advantages. These behaviors are poorly understood in marine mammals but are increasingly studied phenomena in sympatric populations. Resident Atlantic spotted dolphins (Stenella frontalis) off Bimini, The Bahamas, have been the subject of ongoing photo-identification and behavioral studies since 2001. A lesser-known population of bottlenose dolphins (Tursiops truncatus) has been observed interacting with these S. frontalis since 2003. To examine the functional significance of these interactions, interspecific behaviors were documented with underwater video using focal animal sampling. Mating or sexual play were the primary activities observed in nearly 50% of interactions, with male T. truncatus as the initiators. Therefore, the most likely functional explanation for these interactions is social. We hypothesize that male T. truncatus which lack access to T. truncatus females because of sexual immaturity or low social status seek copulations with S. frontalis females as an alternative.

Key Words: Atlantic spotted dolphin, Stenella frontalis, bottlenose dolphin, Tursiops truncatus, Bimini, interspecific interactions, mating

Document Type: Research article

DOI: 10.1578/AM.35.2.2009.281

Page Numbers: 281-291