Song learning in humpback whales: Lessons from song hybridization events during revolutionary song change

Abstract

Humpback whale songs are one of the most startling examples of transmission of a cultural trait and social learning in any non-human animal. Here, we investigate extremely rare cases of song hybridization, where parts of an existing song are spliced with a novel, revolutionary song, to understand how songs are learnt. Song unit sequences were extracted from over 800 phrases recorded during a song revolution (French Polynesia 2005), to allow fine-scale analysis of composition and sequencing. Clustering of song sequences (i.e., phrases) using the Levenshtein distance indicated songs clustered into three song types; a single hybrid phrase was identified representing the transition of one singer between two of these song types. A predictive model was fitted to the data and tested against the only other known recordings of humpback song hybridization: the eastern Australia 1996-97 song revolution. Songs change during revolutions through combining multiple complete phrases and themes from one song type, before ...