The proposed research will focus on the influence of the early social and acoustic environment on the development of the individually-distinctive signature whistles of bottlenose dolphins. Vocal learning is critical for the development of human language but plays a much smaller role in the vocal development of most non-human terrestrial mammals (Janik and Slater 1997). Several studies have reported that bottlenose dolphin calves developed signature whistles that matched acoustic models in their environment, including the whistles of unrelated animals and man-made whistles (Caldwell and Caldwell 1979, Sayigh 1992, Tyack 1997). Preliminary evidence indicates that the early social environment influences how quickly the signature whistle develops and which model the calf matches (Sayigh 1992, Tyack and Sayigh 1997). Bottlenose dolphins therefore provide a unique opportunity to study social influences on vocal learning in a highly social non-human mammal. The objective of the proposed research is to investigate the factors that influence the development of signature whistles, and in particular, the calf s choice of model. The acoustic and social environment experienced by five free-ranging calves will be recorded in each of two years. The research will take place in Sarasota, FL, where a more that 25-year project has tracked the life-history, behavior, and acoustic repertoires of a population of free-ranging dolphins (Wells 1991). The calves will be followed, using focal animal sampling (Altmann 1974), to determine the whistles they hear and their social relationships with their adult companions. New methods will be used that allow the identification of which dolphin in a group is vocalizing, the unbiased analysis of large samples of whistles, and the determination the social relationships between dolphins (Miller and Tyack in press, Fripp et al. 1997a, b, 1998). The most similar whistle to the calf s will be called that calf s model and the dolphin producing it the calf s tutor . The social relationships between the calves and their tutors will be evaluated to determine what social factors play a role in the choice of tutor. The rate the model whistle was produced in the calf s early environment will be used to assess the importance of acoustic factors.