Signal coordination in marine mammals: Cues from the time domain of vocal interactions

Marine mammals are renowned for a precise coordination of social behaviors. To further elucidate these accomplishments, we investigated the time domain of vocal interactions and also relationships between the quality and the coordination mode of signals. Subjects (n=10) were bottlenose dolphins (Tursiops truncatus) which produce several structurally diverse vocalizations: e.g. burst-pulse sounds (bursts) and whistles. Our study revealed that bursts were responded to by bursts only, which occurred status-related within a small time window after stimulus end (latency. similar to 0.2 s). Responses to whistles were status-related too, but occurred with a different timing and more flexible and as either other whistles or directed locomotion. These findings document that the coordination mode of dolphin signals is related to both social and signal class-specific properties. As the time of signal transmission is strikingly short in an aquatic medium, we conclude that marine mammals perform a highly sophisticated form of signal processing.