Common bottlenose dolphin (Tursiops truncatus) whistles and clicks across foraging contexts

Common bottlenose dolphins (Tursiops truncatus) rely on whistles for group cohesion and coordination and on echolocation for prey detection and capture. In Texas bays, dolphins recurrently feed near shrimp trawlers and along seawalls, where they encounter different anthropogenic noises and prey availabilities. We used passive acoustic monitoring to compare whistles and click trains produced by dolphins foraging in these two human-modified habitats in the Texas Coastal Bend. Whistle sequences near trawlers exhibited greater contour diversity and complexity than those near seawalls, likely reflecting developmental and social influences within large mixed-age aggregations that included calves and young-of-year. Elevated group-level click and buzz activity near trawlers primarily reflected large group sizes rather than increased clicking by individuals, indicating collective echolocation effort. Higher proportions of buzz clicks and buzz-containing trains near trawlers indicate increased foraging effort and repeated prey-capture attempts when exploiting trawler-aggregated prey. Short, sparse, and more variable click trains near seawalls are consistent with exploratory echolocation in a less predictable foraging environment where the benefits of eavesdropping are reduced. The data show that social structure, prey resources, and habitat-specific noise shape communication and echolocation across the two foraging contexts.