Acoustic richness and composition changes of humpback whale (<i>Megaptera novaeangliae</i>) songs on breeding grounds off the coast of Ecuador

Abstract Song evolution and revolution events recorded through time are typical cultural features for humpback whale ( Megaptera novaeangliae ) populations worldwide. However, it is unknown if song dynamics are equivalent among subpopulations or breeding stocks of the South Pacific Ocean. To contribute to the understanding of the temporal song dynamics of humpback whale song off the coast of Ecuador, we analyzed acoustic richness and repertoire composition based on unit, phrase, and song composition over consecutive breeding seasons from 2012 to 2019. We observed incomplete song revolutions (all themes were replaced except one) and a nonsignificant variation in the acoustic richness during the study period. Our results show that over the years, humpback whale singers incorporate acoustic material from different subpopulations such as Central South Pacific (French Polynesia) and western South Atlantic (Brazil) into their song repertoire. The temporal acoustic contact of different subpopulations migrating through the eastern South Pacific may be reflected in their particular acoustic richness and temporal evolution. Off the coast of Ecuador, humpback whale song patterns point towards an alternative scenario of song evolution, indicating how cultural transmission among subpopulations can alter the song patterns in specific breeding grounds due lack of geographical barriers surrounding the southeastern Pacific region.