Worldwide Change in Blue Whale's Song Baffles Scientists

The function of whale song, even the better-studied song of the humpback whale, has long baffled marine scientists. Songs of the blue whale, the planets largest living creature, can be divided into at least 10 types worldwide, each type retaining the same units and similar phrasing over decades, unlike humpback whale song which changes substantially from year to year. That is until recently with a  worldwide occurrence of a nearly linear downward shift in the tonal frequencies of blue whale song. web link
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