DURHAM, NC -- Humpback whales are famed for their songs, most often heard in breeding season when males are competing to mate with females. In recent years, however, reports of whale songs occurring outside traditional breeding grounds have become more common. A new study may help explain why.
Humpbacks sing for their supper -- or at least, they sing while they hunt for it.
The research, published December 19 in PLoS ONE, uncovers the whales' little-understood acoustic behavior while foraging.
It also reveals a previously unknown behavioral flexibility on their part that allows the endangered marine mammals to balance their need to feed continuously with the competing need to exhibit mating behaviors such as song displays.
"They need to feed. They need to breed. So essentially, they multi-task," said study co-author Ari S. Friedlaender, research scientist at Duke University's Nicholas School of the Environment. "This suggests the widely held behavioral dichotomy of breeding-versus-feeding for this species is too simplistic."
Researchers from the U.S. Naval Postgraduate School, the University of California-Santa Barbara and Duke tracked 10 humpback whales in coastal waters along the Western Antarctic Peninsula in May and June 2010. The peninsula's bays and fjords are important late-season feeding grounds where humpbacks feast on krill each austral autumn before migrating to warm-water calving grounds thousands of miles away.
Using non-invasive multi-sensor tags that attach to the whales with suction cups, the researchers recorded the whales' underwater movements and vocalizations as they foraged.
All 10 of the tags picked up the sounds of background songs, and in two cases, they recorded intense and continuous whale singing with a level of organization and structure approaching that of a typical breeding-ground mating display. The song bouts sometimes lasted close to an hour and in o
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