Bowhead whale songs are complex and copied, new study shows

Inuit legend says Sedna, the beautiful but tragic goddess of the ocean, sings underwater to give detailed instructions to the whales and other sea animals.

Now scientists have new information about the level of detail in the songs that bowhead whales sing to one another when they are migrating into the Beaufort Sea each spring.

The findings, from sound recordings made in the spring of 2011 by a consortium of scientists from several institutions, are described in a detailed study published online Dec. 30 in the journal Marine Mammal Science.

The researchers documented 12 unique songs sung by at least 32 individual whales while swimming off Point Barrow. It is the greatest number of songs cataloged during the population's spring migration, possibly a result of the growing population, says the study, a joint project of scientists from Bates College, the University of Washington, the North Slope Borough, Norway's FRAM-High North Research Centre for Climate and the Environment and Cornell University.

From the evidence gathered in the study -- the recordings collected during the spring -- the scientists are confident that bowhead whales are sharing their complex songs, said study co-author Kate Stafford of the University of Washington's Applied Physics Laboratory.

Among whales, only bowheads and humpbacks have elaborate and complex songs, Stafford said. But while pods of humpbacks all sing the same tune each migration, bowheads appear to be the only whales that have such a varied repertoire of shared songs during a single migration season, she said.

The songs -- in a low register and distinguishable from the higher-register bearded seal and beluga whale calls -- have a particular style, Stafford said.

"It's something like a crazy screech. It's something like a bassoon. It's something like a trumpet fart," she said. "You have to be very fond of bowheads to consider them beautiful, and I happen to be very fond of bowheads."

The songs are believed to be messages delivered by males to each other demonstrating reproductive fitness, she said.

To record the songs, the scientists deploy sonobuoys, sphere-shaped devices somewhat resembling exercise balls, that can stay on the surface of the seafloor for six months and return to the surface when sent an electronic signal, she said.

Cornell's Bioacoustics Research Program, the North Slope Borough and other organizations have been documenting bowhead calls and other animals' noises in Beaufort for years. The recordings are used to help determine the population, estimated at nearly 17,000 as of 2011 and growing at a rate of 3.7 percent each year, according to the most recent census issued by the borough.

The recording devices are placed in locations ranging from the Bering Sea to nearly 1,500 miles away in the Canadian Beaufort, capturing the whales' songs as they move through their migratory route, Christopher Clark, a senior scientist with Cornell's Bioacoustics Research Program, said at last week's Alaska Marine Science Symposium.

The devices pick up a lot more noise than the bowheads, Clark and Stafford said. Along with the chorus of bowhead songs making their spring migration are sounds from other animals and their marine surroundings.

"In the spring, it's such a noisy environment anyway, from all the bowhead whales and all the bearded seals and all the beluga whales, and ice is extraordinarily noisy itself," Stafford said.