Food talk: 40-Hz fin whale calls are associated with prey biomass

• Published in: Proceedings of the Royal Society B: Biological Sciences
• Main Authors: Romagosa, Miriam, Pérez-Jorge, Sergi, Cascão, Irma, Mouriño, Helena, Lehodey, Patrick, Pereira, Andreia, Marques, Tiago A., Matias, Luís, Silva, Mónica A.
• Other Authors: ERDF, European Union's Horizon 2020 research and innovation programme, US NAVY, Portuguese Ministry for Science and Education, POPH, COMPETE, Fundo Europeu de Desenvolvimento Regional, QREN, ESF, Lisbon Regional Operational Programme, Fundação para a Ciência e Tecnologia, Fundo Regional da Ciência e Tecnologia, Eropean Union
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 2021
• Subjects: Balaenoptera physalus; Fin whale
• Online Access: http://dx.doi.org/10.1098/rspb.2021.1156; https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2021.1156; https://royalsocietypublishing.org/doi/full-xml/10.1098/rspb.2021.1156

Animals use varied acoustic signals that play critical roles in their lives. Understanding the function of these signals may inform about key life-history processes relevant for conservation. In the case of fin whales ( Balaenoptera physalus ), that produce different call types associated with different behaviours, several hypotheses have emerged regarding call function, but the topic still remains in its infancy. Here, we investigate the potential function of two fin whale vocalizations, the song-forming 20-Hz call and the 40-Hz call, by examining their production in relation to season, year and prey biomass. Our results showed that the production of 20-Hz calls was strongly influenced by season, with a clear peak during the breeding months, and secondarily by year, likely due to changes in whale abundance. These results support the reproductive function of the 20-Hz song used as an acoustic display. Conversely, season and year had no effect on variation in 40-Hz calling rates, but prey biomass did. This is the first study linking 40-Hz call activity to prey biomass, supporting the previously suggested food-associated function of this call. Understanding the functions of animal signals can help identifying functional habitats and predict the negative effects of human activities with important implications for conservation.