Do Whales Sing to Their Own Tune? Comparing the Variability Within and Between Song Events of the Eastern Indian Ocean Pygmy Blue Whale

Abstract

Acoustic data from the Perth Canyon, Western Australia, were collected for the 2017 northern migration allowing for detailed acoustic analysis of eastern Indian Ocean pygmy blue (EIOPB) whale songs within a migratory season to explore fine-scale variability in song production. An algorithm was used to follow the unit II signal in time, tracking the change in frequency over the duration of the signal and enabling a comparison of song unit production within and between singing bouts. The results of this analysis indicate that units from within the same song event have relatively consistent characteristics but vary between song events, suggesting it is possible that individual whales may have distinct vocal characteristics. The presence of breaks within a unit was identified as a significant level of variability in song production within the 2017 data set and was seen to increase throughout the season. It is hypothesised that unit breaks may play a role in intra-species communication as well as represent a novel variation to song production that increases song complexity and thus may increase individual fitness through sexual selection.