The conspecific avoidance strategies of adult female-calf humpback whales

• Published in: Behavioral Ecology
• Main Authors: Indeck, Katherine L, Noad, Michael J, Dunlop, Rebecca A
• Other Authors: Ridley, Amanda, Joint Industry Programme on E&P Sound and Marine Life, International Association of Oil & Gas Producers, BG group, BHP Billiton, Chevron, ConocoPhillips, Eni, ExxonMobil, IAGC, Santos, Statoil and Woodside, United States Bureau of Ocean Energy Management, Origin Energy, Beach Energy, AWE
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2021
• Subjects: Humpback Whale; Megaptera novaeangliae
• Online Access: http://dx.doi.org/10.1093/beheco/arab031; http://academic.oup.com/beheco/article-pdf/32/5/845/40787195/arab031.pdf

Abstract During migration, humpback whale (Megaptera novaeangliae) adult females and their calves use acoustic calling to help maintain contact. The signals produced by these pairs, however, may unintentionally attract nearby breeding males, which can result in interactions that have negative physical and physiological effects on the calf. Therefore, maternal females must choose the vocal and/or behavioral strategy that most effectively balances intra-pair communication with male avoidance. Here, we analyzed differences in adult female-calf vocal activity and movement behavior according to the presence of, and distance to, singing whales and other groups likely to contain males. The results of this study found that these pairs make only minimal changes to their vocal behavior in response to nearby males, suggesting that they have instead evolved calls that are naturally difficult to detect (i.e., produced at significantly lower rates and acoustic levels than other whale groups, resulting in a restricted active space). In addition, they maintain spatial separation from nearby groups by moving to shallower, inshore waters, increasing their proportion of time spent near the surface, and favoring a direct migratory course. This combination of cryptic strategies balances avoidance of unwanted conspecific interaction with the necessity of continued contact between maternal female humpback whales and their calves.