Pre-and post-partum whistle production of a bottlenose dolphin (Tursiops truncatus) social group

Abstract

The signature whistle of the Atlantic bottlenose dolphin (Tursiops truncatus) is a well studied acoustic signal known for broadcasting identity and maintaining contact with conspecifics. Several studies have investigated the use of this signal surrounding the birth of calves to dolphin social groups, although some discrepancies exist between the findings of these studies. The current study was an attempt to reconcile some of the inconsistencies through the investigation of signature whistle production by a bottlenose dolphin group two months prior to and two months following the birth of a calf to one of the social group members. We found that the production of signature whistles matching the contour belonging to the dolphin mother increased significantly in both the pre-and post-partum period. Heightened production of the mother's signature whistle type in the first week of our focal calf's life supports the establishment of a recognition system within this time period. Given that learning processes associated with the sound environment appear to begin shortly after calf birth, we also explored the signature whistle rates of the other social group members in an effort to determine whether any signature whistle production influenced the development of the dolphin calf's own signature whistle type. We found that the signature whistles of the other social group members were produced significantly less than the mother's signature whistle until after the first week post-partum. Although the calf did not appear to develop a signature whistle during the length of the study, there was no substantial evidence that the whistles from other group members influenced the calf's whistle production.