Effect of Boat Activity on the Acoustic Communication of Bottlenose Dolphins (Tursiops Truncatus) of Dolphin Bay, Bocas Del Toro, Panama

Bottlenose dolphins emit whistles that play an important role in their communication and social structure. Dolphin whistles are classified as either variant, which are not individual specific, and are produced in the context of group cohesion, or signature, which are individual specific and used to identify specific group members. Given the role whistles play on dolphin communication and behavior, I study the impact of boat activity on the emission of whistles types, the context, and the whistle acoustic structure. I used recordings obtained from multiple years using broadband recordings systems deployed from boats and recently deployed autonomous recordings systems at the Bocas del Toro in Panama. Using both active and passive recordings allowed for the behavioral context of some whistles to be known, as well as for 24-hour examination of whistle emission. Preliminary analysis indicates the emission of 40 different signature whistles, which correspond to estimations of the population size. The majority of signature whistles were emitted during social behaviors and while tour boats were present, supporting signature whistles’ use as contact calls. Additionally, preliminary results of the acoustic structure of whistles found that in the presence of boats, variant whistles showed no change while signature whistles had longer durations and higher frequencies. This supports research done indicating the signature whistle contour conveys identity information, as the acoustic structure seems to be flexible. This study shows the importance of separating whistles into variants and signature as by looking at the changes in whistles overall, important effects such as the influence of boat noise on the frequency of signature whistles can be overlooked. Additionally, this research is crucial for developing better conservation strategies for dolphin populations as more boats are affecting the animals, and thus a better understanding of the boats’ impacts and the dolphins’ responses to them must be acquired