Insights into a complex communication system from tagged bottlenose dolphins

Abstract

Since 2011, we have deployed 30 acoustic and movement logging DTAGs on long-term, multi-generational resident bottlenose dolphins in Sarasota Bay, Florida, for a total of approximately 140 h. Twenty-two tags were deployed simultaneously on pairs of associated individuals, allowing for greater resolution of individual vocal activity. Virtually all dolphins in the Sarasota Bay community are identifiable both visually and by means of their individually distinctive signature whistles. Tags were attached during brief capture-release health assessments, and behavioral observations of tagged individuals post-release continued for as long as possible. Tag data reveal unique insights into foraging behavior, including distinctive acoustic and movement patterns associated with particular foraging modes (e.g., “pinwheel feeding”). In addition to echolocation clicks and buzzes, several distinctive pulsed sounds were recorded on the tags. Whistle copying was observed 18 times in a preliminary analysis of approximately two hours of data, and at least one instance involved more than two dolphins producing the same whistle. Finally, we obtained evidence for at least one shared, stereotyped non-signature whistle. Combining extensive longitudinal information on individual dolphins with fine scale behavioral and acoustic data provides tremendous opportunities for describing and quantifying the complexity of the bottlenose dolphin communication system.