SIGNATURE WHISTLE VARIATIONS IN A BOTTLE-NOSED-DOLPHIN, TURSIOPS-TRUNCATUS

To examine whether context-specific information is superimposed upon t he individual cues present in the whistling of the bottlenosed dolphin , Tursiops truncatus, parameter variations within the two most frequen tly emitted whistle types of a captive individual were investigated in three different behavioural contexts. The study concentrated on compa ring signal features of spontaneously occurring vocalizations in two p ossible phases following the performance of a trained discrimination t ask and those occurring during isolation. Phases of the discrimination task differed according to whether the animal showed ''correct'' (rew ard given) or ''incorrect'' performance (no reward). Signature whistle s were most common in isolation, but also represented just over half o f the whistles following a choice task. Of 14 signature whistle freque ncy and time parameters measured 9 differed significantly between isol ation and at least one of the phases following a choice task (Table 1) . Three parameters also varied according to whether performance was co rrect or incorrect. In contrast, only one out of four parameters (star t frequency) measured from the second most frequent whistle type varie d significantly between contexts (isolation vs. phase following correc t choice). The results indicate that not only identity but also contex t-related information is available in the whistles of a bottlenosed do lphin.