Communication allows species to exchange information, and in aquatic environments, acoustic signals are among the most effective forms of communication. Beluga whales (Delphinapterus leucas) are highly vocal, yet littleis known about the functionality of social calls. To examine context-dependent vocal behavior, we collected passive acoustic data and behavioral observations for the endangered Cook Inlet population. This dataset includes 1 720 annotated vocalizations collected over 21 encounters. We fit two mixed models to investigate the effect of behavior, group size, calf presence, and tidal state on 1) calling rate (calls/min) and 2) call category (whistles, pulsed calls, combined calls). Belugas were more likely to call when traveling and had higher calling rates during flood tides. Group calling rate increased sublinearly with group size, suggesting that individuals called less in larger groups. Group calling rate increased before behavioral transitions, suggesting a possible link between communication and group-level decisions. Whistles were prevalent when traveling, while pulsed calls were prevalent when milling. Further, combined calls occurred only when calves were present, indicating the importance of these calls in mother-calf communication. Identifying these communication patterns and the contexts in which they occur can aid in our understanding and conservation of belugas and social cetaceans more broadly.
Brewer et al. (Wed,) studied this question.
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