Studies shed new light on blue whales

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U.S. researchers have discovered blue whales — the largest mammals on Earth — use calls tied to specific behavior and gender.

Scientists at the Scripps Institution of Oceanography at the University of California-San Diego, in a separate study, used recordings of blue whale songs to determine the animal’s population distributions worldwide.

While the specific function of songs and calls produced by whales remains largely a mystery, the researchers say the sounds are thought to mediate social interactions.

The first study, led by Scripps postdoctoral researcher Erin Oleson and Scripps scientist John Hildebrand, describes the behavioral context of calls produced by eastern North Pacific blue whales.

The researchers found only males produced sounds known as “AB” calls while “D” calls were heard from both sexes, typically during foraging. They note in a paper published in the Jan. 25 issue of the journal Marine Ecology Progress that the sex bias evident in AB callers suggests those calls probably play a role in reproduction.

The second study, published in a recent issue of the Journal of Cetacean Research Management, describes Hildebrand and colleagues’ first attempt at determining worldwide blue whale populations by analyzing nuances of their songs.