Variation in the songs of humpback whales (Megaptera novaeangliae) wintering in the Northwestern and Main Hawaiian Islands

Abstract

A study of the humpback whale song in the Northwestern Hawaiian Islands (NWHI) and the Main Hawaiian Islands (MHI) during the 2009 season suggests that humpback whale song may be more variable than previously suggested. Data from five autonomous acoustic recorders deployed at locations in the NWHI and MHI were analyzed to compare the frequency of occurrence of song units by whales in the island chain. There appears to be a gradient of differences in song units throughout the Hawaiian Island chain, rather than the previously assumed, more discrete differences between breeding populations. Recordings from each site were randomly selected. Song units were classified as one of 23 units and counted to compare between sites. Changes in the frequency of occurrence in a few of the most abundant units suggest a gradual change throughout the island chain. However, this may be confounded by changes that occur throughout the season throughout the ocean basin. Further work examining the amount of variation both between and within humpback whale breeding populations should be conducted.