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Do Social and Dolphin Watching Activities Vary in How They Influence Bottlenose Dolphin Whistle Emission and Acoustic Structure?
O'Connor, Megan Elizabeth
O'Connor, Megan Elizabeth
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Abstract
Bottlenose dolphins (Tursiops truncatus) rely on frequency modulated, narrowband whistles to establish and maintain complex interactions. As dolphins move through their environment, they encounter areas with varying acoustic properties and use them for different purposes. To explore if social and anthropogenic factors vary in the way the influence whistle emission rates and acoustic structure, I studied a small, genetically distinct population of bottlenose dolphins in Bocas del Toro, Panama. This population is isolated from other Caribbean populations and inhabits a region (Dolphin Bay) that has become a hotspot for dolphin-watching tourism. The objectives of this thesis are to determine whether (1) dolphin whistle emission rates and (2) the frequency and temporal characteristics of whistles vary in relation to behavioral activity, group composition, and the presence of boats. These factors have been investigated separately in the past; however, this study takes each into account. Acoustic and behavioral data were collected during boat surveys conducted over 31 days in 2023 and 15 days in 2024, using four-channel broadband recording systems. The results of this study show that whistle emission rates vary primarily with behavior, with dolphins increasing their whistle rate during social activities. Social activities also influenced the acoustic structure of whistles. During social interactions dolphins produced whistles with higher low frequencies, as well as higher peak frequencies. Interestingly, in contrast to previous studies in the area, the impact of dolphin-watching boats on whistle emission rates and acoustic structure was minimal. This may be due to the timing of data collection which occurred outside of peak tourism season, and this study’s inclusion of behavior as a factor. Overall, the findings suggest that when dolphin-watching boat presence is low, social behavior is the primary factory driving variation in whistle emission rates and acoustic characteristics. This study highlights the plasticity of dolphin communication across varying contexts by simultaneously examining behavior, boat presence, and group composition. It also underscores the importance of considering this flexibility when studying bottlenose dolphin populations, offering deeper insight into how they adapt their communication to a dynamic environment.
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2025-01-01