Hawaii's Humpback Whale Song
Song Structure
The humpback whale song is a series of sounds that typically lasts 10–15 minutes and is repeated over and over.
The song consists of several different themes (often four to six) sung in a continuous loop. Each theme is composed of sound units distinctly arranged as a phrase, which is repeated for several minutes. The singer progresses through each of the themes (all with different unit/phrase compositions) until he has worked through the entire song. If the song has four themes the whale will sing themes 1-2-3-4, usually surface to breathe, then dive and begin theme 1 again. A song session (that is, continuous singing) can last hours.
Here the themes (composed as above) are given different colors. All singers in the population follow the same pattern of theme composition and progression. Even the amount of time spent on one theme is similar. During this period (Jan. 2005), about 70 percent of the Hawaii song consisted of theme 3 (yellow).
Sound Spectrographs
Click on the audio-files below to hear the sound of the phases in each theme.
This whale would sing each of these themes in order shown, surface to breathe (after blue theme) then dive and begin again with the pink theme.
Theme 1
Theme 2
Theme 3
Theme 4
Unique Characteristics
The humpback song is unique in that it gradually changes in composition as it is being sung. That is, small changes in song units will change phrase composition and, in turn, entire themes. (For example, aaab aaab in Theme 1 may change to ab ab, then eventually drop out altogether.) Yet all the singers in a population sing the same version of the ever-changing song at any one time. Researchers do not know how this is achieved.
Varying Rates of Change
The rate of song change varies—the reason is unknown. Humpback songs studied in Bermuda and Hawaii in the 1970s and 80s changed gradually, with the entire song composition turning over in four or five years. A more recent study in the late 90s off the east coast of Australia showed potential for more rapid change, with the whales there adopting a song from a western Australia population in its entirety over just a two-year period.
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