The extensive repertoire of bowhead whales
9 October 2018
Virtually all mammals use sound to communicate, but very few produce intricate songs.
One of them is the bowhead whale (Balaena mysticetus), recently studied in the Fram Straight between Greenland and Svalbard. Using recordings, researchers noticed that the Spitsbergen bowheads used distinct song types for relatively short periods of time—a few months at most—and then changed them.
According to a recently released study, these bowhead whales produced more than 184 different song types over a three-year period, a level of diversity the study says is “rivalled only by a few species of songbirds.”
Kit Kovacs, a researcher with the Norwegian Polar Institute and one of the study’s co-authors, says there are several potential theories to explain this extraordinary diversity in song. It may have come about because of an expanding population. Or warmer temperatures could play a role, since whales may “immigrate” to the area from other populations as thick sea ice thaws. It could also be that there is strong pressure for novelty in a small population. Bowheads sing underwater beneath heavy ice during the polar night, so arriving at a detailed understanding of their syntax is challenging.
Listen to a bowhead
This predominantly Arctic species is associated with ice floes. Its movement patterns are therefore influenced by the melting and freezing of the ice. The bowhead has suffered from severe over-exploitation that has seen its range shrink considerably since the 17th century.
Oceans cover more than 70% of the planet. Until recently, the Arctic Ocean was a natural “acoustic refuge” for marine animals because it was covered in thick ice for much of the year.