Humpback whales (Megaptera novaeangliae) possess complex vocal repertoires, yet research on non-song vocalizations remains limited. This study used 69 h of acoustic-video data from CATS tags deployed on 19 distinct individuals (2021–2023) to investigate relationships between social calls and behavior on the Hawaiian breeding grounds. Behaviors were quantified from CATS tag footage, examining swimming speed, social grouping, surface activity, and physical contact. A seven-category social call catalog was developed using the acoustic data and analyzed against behavioral variables using a multinomial mixed-effects model. Swimming speed consistently predicted vocal behavior across all call categories (p0.05), and the whales demonstrated clear frequency–arousal relationships. Both medium- (p0.001) and high-frequency calls (p0.001) were significantly more likely at faster swimming speeds, with speed exerting a stronger effect on high-frequency calls, confirming fundamental mammalian arousal–frequency principles where higher arousal states elicit higher frequency vocalizations. Social context significantly influenced calling patterns. A linear mixed-effects model revealed that dyads exhibited a lower call rate than competitive groups (p0.05) and that mother–calf escort units approached a lower call rate (p = 0.09). These findings reveal that humpback whale social calls follow patterns driven by physiological arousal and social context, demonstrating distinct communicative functions across behavioral states.
Holm et al. (Wed,) studied this question.