Omura's whale (Balaenoptera omurai) song features and structure in northern Australian waters

This paper describes Omura's whale vocalizations recorded off northern Australia. Most common was a two-unit "doublet" (17-50 Hz, peak 25.5 Hz, duration ∼15 s). This was rhythmically repeated for extended periods of time, in typical baleen-whale song structure, suggesting it is a male breeding display. A one-unit "singlet" occurred in the lower-latitude locations off the northwest (13-72 Hz, peak 26.6 Hz, 8 s). In the Great Barrier Reef, similar doublets were detected, identifying a possible population of the species in the Southwest Pacific. Such geographic variation of song may benefit passive acoustic monitoring of this species for conservation management.