Across their range humpback whales (Megaptera novaeangliae) produce a wide array of vocalizations including song, foraging vocalizations, and a variety of non-song vocalizations known as social calls. This study investigates the social calling behavior of Southeast Alaskan humpback whales from a sample of 299 vocalizations paired with 365 visual surveys collected over a three-month period on a foraging ground in Frederick Sound in Southeast Alaska. Vocalizations were classified using visual-aural analysis, statistical cluster analyses, and discriminant function analysis. The relationship between vocal behavior and spatial-behavioral context was analyzed using a Poisson log-linear regression (PLL). Preliminary results indicate that some call types were commonly produced while others were rare, and that the greatest variety of calling occurred when whales were clustered. Moreover, calling rates in one vocal class, the pulsed (P) vocal class, were negatively correlated with mean nearest-neighbor distance, indicating that P calling rates increased as animals clustered, suggesting that the use of P calls may be spatially mediated. The data further suggest that vocal behavior varies based on social context, and that vocal behavior trends toward complexity as the potential for social interactions increases. [Work funded by Alaska Whale Foundation and ONR.]
