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Arthur T Knackerbracket has found the following story:

Spring is the time of year when birds are singing throughout the Northern Hemisphere. Far to the north, beneath the ice, another lesser-known concert season in the natural world is just coming to an end.

A University of Washington study has published the largest set of recordings for bowhead whales, to discover that these marine mammals have a surprisingly diverse, constantly shifting vocal repertoire. The study published April 4 in Biology Letters, a journal of the United Kingdom's Royal Society, analyzed audio recordings gathered year-round east of Greenland. This population of bowhead whales was hunted almost to extinction in the 1600s and was recently estimated at about 200 animals. Audio recordings gathered from 2010 to 2014 indicate a healthy population, and include 184 different songs.

"If humpback whale song is like classical music, bowheads are jazz," said lead author Kate Stafford, an oceanographer at the UW's Applied Physics Laboratory. "The sound is more freeform. And when we looked through four winters of acoustic data, not only were there never any song types repeated between years, but each season had a new set of songs."

Stafford has recorded whales' sounds throughout the world's oceans as a way to track and study marine mammals. She first detected bowhead whales singing off the other side of Greenland in 2007. A previous study by Stafford of the Spitsbergen whales off west Greenland reported in 2012 that the whales were singing continuously during the winter breeding season, the first hint that there may be a healthy population in that area.

"We were hoping when we put the hydrophone out that we might hear a few sounds," Stafford said of the earlier study. "When we heard, it was astonishing: Bowhead whales were singing loudly, 24 hours a day, from November until April. And they were singing many, many different songs."

The new paper extends that initial five-month dataset, and confirms that bowhead whales sing in this region regularly from late fall to early spring. In fact the hydrophones, which are underwater microphones, picked up slightly more singing in the later years of the study. But what was most remarkable was the relentless variety in the animals' songs, or distinct musical phrases.

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