The Bioacoustics of Blue Whales—Global Diversity and Behavioral Variability in a Foraging Specialist

Abstract

Blue whalesBlue whale are the largest animals ever to inhabit our planet. Worldwide they comprise at least four subspecies, currently recognized to make up to 11 distinct populationsPopulation which share a krillKrill-specialized foraging preference. The populationsPopulation are defined by common geography, migratory behavior,Behavior and destinations but can also be delineated by unique songsSong that likely functionFunction as a reproductive display. Male singers in each populationPopulation typically sing the same song typeSong type and share some common behavioral patternsPattern in the use of songsSong and song unitsSong units. Migratory behaviorBehavior and characteristics of their habitat shape the differencesDifferences in the structure of blue whaleBlue whale songsSong among different populationsPopulation. Offshore populationsPopulation tend to have simpler songsSong than populationsPopulation occurring more coastally, possibly reflecting differing propagation environments. In areas of high sympatry, such as the Indian Ocean, the increased complexityComplexity in songSong structure may arise as a result of acoustic competition. Both male and female blue whalesBlue whale also produce other soundsSound, primarily including the so-called D calls,Calls commonly heard associated with foraging behaviorBehavior. These callsCalls are spectrally similar to foraging signals of other balaenopterids, and eavesdropping may be a mechanism for locating productive areas intra- and interspecies. While some balaenopterids fast on breeding grounds and during much of the migrationMigration, blue whalesBlue whale forage along their migrationMigration route and in breeding areas, indicating that preyPrey availability is an important driver of their behaviorBehavior year-round. Fine-scale variabilityVariability in their acoustic behaviorsAcoustic behavior and relationships to their habitat and preyPrey variabilityVariability may be the keys that can help us explain the long-term drivers of blue whaleBlue whale populationPopulation trends. We highlight research questions and possible future directions that would help further enhance our understanding of the interplay between acoustic behaviorAcoustic behavior, diversityDiversity, and ecologyEcology of this species, along with understanding how some present and future threats, including climate change, may impact the populationsPopulation of this charismatic species.

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