(Press-News.org) 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 one case occurred even while sensors indicated the whale, or a close companion, was diving and lunging for food.
Humpbacks sing most frequently during breeding season, but are known to sing on other occasions too, such as while escorting mother-calf pairs along migratory routes. Though the reasons they sing are still not thoroughly understood, one distinction is clear: Songs sung in breeding grounds are quite different in duration, phrase type and theme structure from those heard at other locations and times.
"The fact that we heard mating displays being sung in late-season foraging grounds off the coast of Antarctica suggests humpback whale behavior may be more closely tied to the time of year than to physical locations. This may signify an ability to engage in breeding activities outside their traditional warm-water breeding grounds," said Douglas P. Nowacek, Repass-Rogers University Associate Professor of Conservation Technology at Duke's Nicholas School.
As the region's climate warms, sea ice cover around the Western Antarctic Peninsula has thinned in recent years and the water stays open later in the foraging season, he explained. Whales are remaining there longer into austral autumn to feast on krill instead of heading off to warm-water breeding grounds, as many scientists previously believed.
"Mating may now be taking place at higher latitudes," Nowacek said. "This merits further study."
Alison K. Stimpert, research associate in oceanography at the Naval Postgraduate School, was lead author of the new study. Lindsey E. Peavey, a PhD Student at the University of California at Santa Barbara's Bren School of Environmental Science and Management, co-authored it with Stimpert, Friedlaender and Nowacek.
###Funding was provided by the National Science Foundation.
Friedlaender and Nowacek are stationed at the Duke University Marine Lab in Beaufort, N.C. Nowacek holds a joint appointment as Repass-Rogers University Associate Professor of Electrical and Computer Engineering at Duke's Pratt School of Engineering.
CITATION: : "Humpback Whale Song and Foraging Behavior on an Antarctic Feeding Ground," Alison K. Stimpert, U.S. Naval Postgraduate School; Lindsey E. Peavey, University of California-Santa Barbara; Ari S. Friedlaender, Duke University; Douglas P. Nowacek, Duke University. PLoS ONE, Dec. 19, 2012
Multi-tasking whales sing while feeding, not just breeding
2012-12-20
ELSE PRESS RELEASES FROM THIS DATE:
Scientists construct first map of how the brain organizes everything we see
2012-12-20
Our eyes may be our window to the world, but how do we make sense of the thousands of images that flood our retinas each day? Scientists at the University of California, Berkeley, have found that the brain is wired to put in order all the categories of objects and actions that we see. They have created the first interactive map of how the brain organizes these groupings.
The result – achieved through computational models of brain imaging data collected while the subjects watched hours of movie clips – is what researchers call "a continuous semantic space."
Some relationships ...
Are bacteria making you hungry?
2012-12-20
Over the last half decade, it has become increasingly clear that the normal gastrointestinal (GI) bacteria play a variety of very important roles in the biology of human and animals. Now Vic Norris of the University of Rouen, France, and coauthors propose yet another role for GI bacteria: that they exert some control over their hosts' appetites. Their review was published online ahead of print in the Journal of Bacteriology.
This hypothesis is based in large part on observations of the number of roles bacteria are already known to play in host biology, as well as their ...
Policy report calls for raise in minimum wage
2012-12-20
AUSTIN, Texas — Raising the minimum wage to a living wage begins the cycle of lifting single mothers out of poverty, according to a policy report released by the Institute for Urban Policy Research & Analysis (IUPRA) at The University of Texas at Austin.
The U.S. census shows more Americans — 46.2 million people — are living in poverty than ever before. And for African American and Hispanic women, a full-time minimum wage job isn't enough to break out of the poverty cycle. According to the report, working women of color make $0.64 and $0.56, respectively, for every dollar ...
Soybeans a source of valuable chemical
2012-12-20
The humble soybean could become an inexpensive new source of a widely used chemical for plastics, textiles, drugs, solvents and as a food additive.
Succinic acid, traditionally drawn from petroleum, is one focus of research by Rice chemists George Bennett and Ka-Yiu San. In 2004, the Department of Energy named succinic acid one of 12 "platform" chemicals that could be produced from sugars by biological means and turned into high-value materials.
Several years ago, Rice patented a process by Bennett and San for the bio-based production of succinic acid that employed ...
Scripps Florida scientists develop new compound that reverses fatty liver disease
2012-12-20
JUPITER, FL, December 19, 2012 – Scientists from the Florida campus of The Scripps Research Institute (TSRI) have developed the first synthetic compound that can reverse the effects of a serious metabolic condition known as fatty liver disease. True to its name, the disease involves an abnormal buildup of fat in the liver.
The compound—known as SR9238—is the first to effectively suppress lipid or fat production in the liver, eliminating inflammation and reversing fat accumulation in animal models of fatty liver disease. The new compound also significantly lowered total ...
Regular marijuana use by teens continues to be a concern
2012-12-20
Continued high use of marijuana by the nation's eighth, 10th and 12th graders combined with a drop in perceptions of its potential harms was revealed in this year's Monitoring the Future survey, an annual survey of eighth, 10th, and 12th-graders conducted by researchers at the University of Michigan. The survey was carried out in classrooms around the country earlier this year, under a grant from the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health.
The 2012 survey shows that 6.5 percent of high school seniors smoke marijuana daily, up ...
School shootings: What we know and what we can do
2012-12-20
Since the early 1970s school shootings at American elementary, secondary and higher education institutions have been a painful reality for American society. After each incident – like the recent attack in Newtown, CT – there is voluminous dialogue about what can be done to prevent the next, such tragedy. But can anything realistically be done to prevent these horrific crimes? A new article¹ by Dr. Daniel J. Flannery at Case Western Reserve University, and colleagues, scheduled to appear in the January issue of Springer's Current Psychiatry Reports, attempts to parse out ...
Alzheimer's disease: Cutting off immune response promises new approach to therapy
2012-12-20
The Bonn site of the German Center for Neurodegenerative Diseases (DZNE) and the University of Bonn are leading contributors.
The complex named "NLRP3 inflammasome" is composed of several proteins and plays a key role in the immune system. It resembles a fire alarm sensor that triggers a chain reaction when activated. As a result, immune cells are mobilized and substances that foster inflammation are released. This process can be triggered by infections, which are subsequently suppressed by the immune response. However, in the case of Alzheimer's disease, the activation ...
Impact of caring for adult child with disability studied
2012-12-20
The study, published in Psychiatric Services, highlights economic and psycho-social challenges faced by parents of adult children with disabilities, compared with parents of children without disabilities.
When either parent becomes disabled, the study found, families' report lower financial well-being. This being especially true when an aging parent must contend with both the needs of an adult child with mental illness and a spouse who develops an age-related disability.
Not surprisingly, parents are themselves susceptible to developing disabilities and chronic conditions ...
Super-fine sound beam could one day be an invisible scalpel
2012-12-20
ANN ARBOR—A carbon-nanotube-coated lens that converts light to sound can focus high-pressure sound waves to finer points than ever before. The University of Michigan engineering researchers who developed the new therapeutic ultrasound approach say it could lead to an invisible knife for noninvasive surgery.
Today's ultrasound technology enables far more than glimpses into the womb. Doctors routinely use focused sound waves to blast apart kidney stones and prostate tumors, for example. The tools work primarily by focusing sound waves tightly enough to generate heat, says ...