Abstract
A division of labor with role specialization is defined as individuals specializing in a subtask during repetitions of a group task. This behavior is ubiquitous in humans, but there are currently only four confirmed examples found among non-eusocial mammals; lions, mice, chimpanzees, and bottlenose dolphins. The population of bottlenose dolphins (Tursiops truncatus) in Cedar Key, Florida, is well known for their role-specialized foraging tactic. During “driver-barrier feeding”, a “driver” dolphin herds mullet (Mugil spps.) towards “barrier” dolphins and as the prey are trapped they leap out of the water, where the dolphins catch them in air. However, it is currently unknown how dolphins coordinate driver-barrier behavior. By recording vocalizations with a hydrophone array during a subset of more than 300 observed instances of driver-barrier feeding by 12 different driver individuals, this study is the first to investigate how bottlenose dolphins coordinate during role-specialized behavior. Results of fine-scale audio and video analysis during a subset of ~80 driving events with highest audio quality suggests that barrier animals cue on outgoing and/or reflected echolocation from the driver individual. Analyses of temporal patterning of whistles before and after driving events reveal increased whistle production in the minute before and 30 seconds after driver-barrier events. Whistle rates did not vary across different drivers, solo versus group events, or with varying success, suggesting that whistles are functionally relevant to the behavior and not a product of differences between individuals or event success. These whistles could vary in function, including expressing motivation, recruiting individuals to participate, and/or coordinating the behavior. The results of this study inform our understanding of the role dolphin vocalizations play in role-specialization and role-specialization.