Singing bowhead whales baffle scientists

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Singing bowhead whales baffle scientists

September 15, 2013 - 19:08
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Some 66 different tunes recorded despite low population

Bowhead tail fluke

While the population of bowhead whales off Greenland is estimated to be in the mere tens, they make up for the low numbers in songs. University of Washington oceanographer Kate Stafford, together with a team of US and European scientists, has recorded whales singing some 66 different tunes. "To have over 60 songs was remarkable,” especially from what we considered to be a remnant population, " said Stafford.

For her research in the Fram Strait, Stafford and her team secured two microphones underwater, recording nine-minute long segments every 30 minutes for a year.
"We thought we were going to be looking for a needle in a haystack," Stafford said. "Or listening for a needle in a haystack. You leave these instruments out for a year and you don't know whether or not they've worked until you get them back."

Final analysis revealed thousands of hours of bowhead whale songs, each lasting 45 to 60 seconds each. The majority was logged between November and March, indicating the area has probably become both a wintering and mating ground.” There was a clear progression through the season of completely different songs," said Stafford, adding that the reason for this remains unknown.

One theory is that the bowheads' songs are used not just to attract mate but also for enjoyment. Stafford wonders if the songs might work a bit like communal pop music charts. "You know the songs that were playing when you were in high school? Even when you hear them a few years later, you know exactly the year they came out," she said. "Maybe it works like that, maybe there's a song of the year. And you have all these cohorts of these very long-living animals maintaining that song."

Bowheads, named for their distinctive long skulls, were nearly hunted to extinction near Greenland 200 years ago by Dutch traders. Today, only four populations of bowhead whales remain in the Arctic Circle, from the Bering Strait to the Fram Strait east of Greenland. One feature unique to bowheads is their ability to produce high and low frequency tones simultaneously, giving the effect of singing with two voices.

Whale songs usually commence with a few notes or phrases, enter a more complicated stretch and then close with a low, loud bellow. The sounds fall right within human hearing range.

Stafford plans to make additional bowhead recordings in the Beaufort Sea north of Alaska and in the Davis Strait west of Greenland in future. Given the funding, she would also like to return to the Fram Strait to discover if it is one bowhead or many that is responsible for a number of songs in a given timeframe. "I'm not a whale hugger," she said, "but I'm just so impressed with these animals," she added.