Humpback whale alters song if another one sings along
Study offers a new way to explore tunes’ meanings
By Susan Milius
November 7th, 2009; Vol.176 #10 (p. 5)
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Whale songA new approach to studying the songs of humpback whales (two shown here west of Mexico) finds that they may respond to each other musically. D. Cholewiak
Quebec City, Canada — Like a songbird calling another out, one male humpback whale may make another change his tune.
Studying humpbacks with methods adapted from bird research has uncovered the first known instances of what look like whales responding musically to each other’s songs, says Danielle Cholewiak, a researcher for the Stellwagen Bank National Marine Sanctuary based in Scituate, Mass. Cholewiak and colleagues detected melodic adjustments when a solo singer encountered another singer nearby and when researchers played their song remixes for whales. Male whales may be using music to tell another male, “Hey, I’m talking to you,” Cholewiak reported October 14 at the Society of Marine Mammology’s biennial conference. Cholewiak “showed short-term acoustic interactions between males — that was the new thing,” said Adam S. Frankel of Marine Acoustics Inc., an independent consulting firm in Arlington, Va. Enlarge
Recording the songAs part of a recent study, Danielle Cholewiak dropped pop-up recorders into the ocean to record whale songs. S. Cerchio
Among humpback whales, only males boom out long strings of repeating phrases of hums and whups and chirps. The sounds can make a boat vibrate, said Salvatore Cerchio of the Wildlife Conservation Society in New York City, who worked with Cholewiak on the new study. Scientists use the word song to describe this patterned male vocalization, just as they do for elaborate bird serenades. Male songbirds sing at each other to claim their territory or seduce females. Though humpbacks don’t defend territories, they certainly have rivalries. Typically three to eight males surround a female and battle for the position closest to her. “These guys are streaming blood,” Cerchio said. “The gentle giant is a myth.” But observations so far haven’t helped scientists understand whether humpbacks use songs the way birds do. Tests haven’t shown male or female humpbacks consistently swimming toward or away from recorders playing songs. And scientists have yet to see humpbacks mate. So instead, Cholewiak took a different approach, boating around a breeding ground recording and analyzing songs. Enlarge
Visualizing whale song via waveformThese waveform images show song from a house wren (top) and humpback whale (bottom). Bursts of sound appear as dark shapes, where bigger means louder. Correlating song patterns with bird behavior has helped researchers understand the function of their songs, but comprehending whale song function has proven difficult. Adapted from Macaulay Library's Raven Viewer/ Cornell Lab of Ornithology
“I was drooling over what she was able to do,” says Sharon Nieukirk of Oregon State University’s Hatfield Marine Science Center in Newport, Ore. Whales rarely cooperate with field biologists’ experimental plans. Cholewiak undertook the song analysis while at Cornell University, which has a renowned flock of birdsong researchers. She adapted measurements used in bird studies to analyze the humpbacks’ songs. For example, the whales repeat a phrase of notes several times in one block, or “theme,” before moving on to another, and Cholewiak looked at how often the whales switched among these themes. .
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