Signature Whistle Production during a Bottlenose Dolphin Group Integration

Bottlenose dolphins are an important species of interest because they possess a variety of abilities that are relatively rare in the animal kingdom, one being complex acoustic communication. Signature whistles - distinctive calls that are unique for each individual – are one of the most studied call types, but we know little about how these calls are used in various contexts, such as during an introduction. Looking at the socio-behavioral context in which signature whistles are used is likely the best way of learning how these whistles are used in a particular context (Caldwell, Caldwell, & Tyack, 1990). For this project, the behavior and vocalizations of dolphins that were being introduced for the first time were analyzed to assess how signature whistle production and behavior changed after introduction. The new individual, a juvenile male, was kept physically, but not visually and acoustically, separated during the introduction. Signature whistle production for the new dolphin declined steeply on the day of introduction, increased the following week, and almost fully recovered over a month later. Overall, he produced approximately three times more signature whistles than the other dolphins. The resident female showed interest in the new individual following the initial introduction, and her signature whistle production increased after the introduction. The resident adult male showed little interest in the newcomer and his signature whistle production increased slightly. Following introduction, there were only slight changes in the behavior of resident group members, which included increased circle swimming and object play. Circle swimming also increased significantly for the new individual. There were no differences in social behavior and no agonistic behaviors were observed. The new dolphin’s decrease in signature whistling on the day of introduction was unexpected but may be due to individual differences in response to stress. In some ways, these findings are inconsistent with the few reports of typical bottlenose dolphin behavior during an introduction. Information from additional introductions will be needed to determine if the patterns of signature whistle usage and behavior seen here are typical of the range of behaviors exhibited in this context