The Hawaiian archipelago is the principal breeding ground of the north Pacific humpback whale (Megaptera novaeangliae) population. Recent evidence indicates that in addition to occupying the inhabited main Hawaiian Islands (MHI), humpback whales are also present in many parts of the uninhabited Northwestern Hawaiian Islands (NWHI) during the winter breeding season. Further, the distribution along the island chain is not homogenous. This broad, fragmented range raises the possibility that more than one distinct population segment could utilize the archipelago. To examine this question, humpback whale song obtained using bottom-moored recorders in the MHI and NWHI and from an acoustic Wave Glider survey of the NWHI were analyzed to examine similarities in song unit and phrase structure. In total, 10 songs from the MHI and 25 from the NWHI were characterized. Results reveal that although substantial overlap in song structure exists across the archipelago, variability is also present. Singers recorded at French Frigate Shoals in the NWHI (700 km northwest of Kaua‘i) exhibited higher inter-individual variability that suggests more heterogeneity in song structure than singers off Maui in the MHI. The results suggest that additional efforts should be made to further resolve the population structure of whales across the Hawaiian archipelago.
Lammers et al. (Wed,) studied this question.