Acoustic behavior of humpback whale calves on the feeding ground: Comparisons across age and implications for vocal development

PLoS One. 2024 May 29;19(5):e0303741. doi: 10.1371/journal.pone.0303741. eCollection 2024.

Abstract

Studying sound production at different developmental stages can provide insight into the processes involved in vocal ontogeny. Humpback whales (Megaptera novaeangliae) are a known vocal learning species, but their vocal development is poorly understood. While studies of humpback whale calves in the early stages of their lives on the breeding grounds and migration routes exist, little is known about the behavior of these immature, dependent animals by the time they reach the feeding grounds. In this study, we used data from groups of North Atlantic humpback whales in the Gulf of Maine in which all members were simultaneously carrying acoustic recording tags attached with suction cups. This allowed for assignment of likely caller identity using the relative received levels of calls across tags. We analyzed data from 3 calves and 13 adults. There were high levels of call rate variation among these individuals and the results represent preliminary descriptions of calf behavior. Our analysis suggests that, in contrast to the breeding grounds or on migration, calves are no longer acoustically cryptic by the time they reach their feeding ground. Calves and adults both produce calls in bouts, but there may be some differences in bout parameters like inter-call intervals and bout durations. Calves were able to produce most of the adult vocal repertoire but used different call types in different proportions. Finally, we found evidence of immature call types in calves, akin to protosyllables used in babbling in other mammals, including humans. Overall, the sound production of humpback whale calves on the feeding grounds appears to be already similar to that of adults, but with differences in line with ontogenetic changes observed in other vocal learning species.

Publication types

  • Comparative Study

MeSH terms

  • Acoustics
  • Animals
  • Feeding Behavior / physiology
  • Female
  • Humpback Whale* / physiology
  • Male
  • Vocalization, Animal* / physiology

Grants and funding

Funding for this research was provided by Stellwagen Bank National Marine Sanctuary, the Office of National Marine Sanctuaries, the National Oceanographic Partnership Program, and the Office of Naval Research, Award Number N00014-08-1-0630 (SEP and DNW). JMZ was funded by the National Defense Science and Engineering Graduate Fellowship. SEP was supported by the ACCURATE Project (Contract No. N3943019C2176) and SEP and FHJ by the Cetacean Caller-ID project (Contract No. N3943023C2502) funded by the U. S. Navy Living Marine Resources Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.