Sperm whales like to be individuals; they use accents to identify themselves to others in their extended family group, new research finds.
The accents are specific to one call, or "coda," used by whales worldwide, enabling them to recognize strangers from any region.
"It's not that the individuals in a group are making different codas, they don't have different names, they just say the same things in different ways," said study researcher Shane Gero, of Dalhousie University in Halifax, Nova Scotia, Canada. "We believe they can pick between each other, that they can tell each other apart by this call."
Sperm whales live in family groups, with several generations of females living together with their young. They communicate using these codas, specific combinations of clicking sounds. The codas travel for about a kilometer in the ocean, and they are used mostly within a group to communicate during dives and social situations.
The team followed one group of sperm whales, called the "group of seven," made up of four sisters, their aunt and two juvenile males, for more than 40 days while the animals fed off the coast of Dominica, a Caribbean island.
They found that one of these codas, called the "five regular" for its five consecutive clicks, is pronounced by individual whales in different ways, and can be used to identify individuals by how the clicks are accented or the timing between consecutive clicks.
Previous research had shown that sperm whales are able to identify, and preferentially spend time with, certain group members. This doesn't seem like a great feat to landlubbers like humans, but in the deep, dark ocean vision isn't something whales can rely on, so they have to find other ways to hunt and identify themselves.
The "five regular" call is one of the few codas that all sperm whale groups, no matter where they live — the Caribbean, the Pacific or the Mediterranean Sea — use in their regional dialects. "The fact that it's that one that appears to carry a signal of identity is pretty interesting," Gero told LiveScience. "You don't want to mess up the call that everyone uses to identify everyone."
Increasing ocean noise, from underwater drilling operations and shipping traffic, may interfere with these social calls. "These calls are important, likely, for keeping groups together and also for knowing where and if another group is coming up. Their whole life is based on sound," Gero said. "When you increase the background noise, you start disrupting their lives."
Continued observation of these animals over the years and in different social situations will give the researchers more clues to how they use these calls.
The study was published in the April 2011 issue of the journal Animal Behavior.
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Interpreting the language of whales
Whales have accents and regional dialects.
Katherine Wooler - May 11, 2011
Dalhousie PhD student Shane Gero likes to talk to the animals—whales to be exact. And not so much talk as listen.
Recently returned from a seven-week visit to Dominica, Mr. Gero has been travelling to the Caribbean island since 2005 to study families of sperm whales, usually spending two to four months of each year working on the Dominica Sperm Whale Project. One of the goals of this project is to record and compare whale calls over time, examining the various phrases and dialects of sperm whale communities.
Whale talk
When they dive together, sperm whales make patterns of clicks to each other known as “codas.” Recent findings suggest that, not only do different codas mean different things, but that whales can also tell which member of their community is speaking based on the sound properties of the codas. Just as we can tell our friends apart by the sounds of their voices and the way they pronounce their words, different sperm whales make the same pattern of clicks, but with different accents.
Caribbean and Pacific whales have different repertoires of codas, like a regional dialect, but the “Five Regular” call—a pattern of five evenly spaced clicks— is thought to have the universal function of individual identity because it is used by sperm whales worldwide.
These discoveries were recently published in the journal Animal Behaviour, in an article authored by University of St. Andrews PhD student Ricardo Antunes, Dal alumnus Tyler Schulz, Mr. Gero, Dal professor Dr. Hal Whitehead, and St. Andrews faculty members Dr. Jonathan Gordon and Dr. Luke Rendell.
A world of sound
Mr. Gero and Dr. Whitehead explain that the sperm whale’s biggest threat is human pollution. Not only do humans introduce toxins into the ocean, but they also generate harmful sound pollution. Increased shipping traffic, underwater explosions caused by searching for oil, and military sonar all contribute to ocean noise that masks communication between whales.
“No one wants to live in a rock concert,” says Mr. Gero, adding that noise pollution is especially troublesome in the ocean because “it is a totally different sensory world.” The sperm whales can dive to depths of more than 1,000 metres and depend on sound for communication and navigation in the pitch black of the deep water.
The Dominica Sperm Whale Project hopes to understand more about sperm whale society because, as Mr. Gero says, “it is infuriating that we know more about the moon than the oceans.” He hopes to communicate a better understanding of life in the oceans to people by using these beautiful whales as examples, and by placing an emphasis on “how similar their lives actually are to ours.”
Family values
The whales live in matriarchal social units composed of mothers, daughters, and grandmothers. Once males reach adolescence, they are ostracized from the group and travel towards the poles until they are ready to breed. Consequently, little is known about the males, but the roles of females in relation to their young have been studied extensively by Mr. Gero and Dr. Whitehead. Female whales will baby-sit each other’s offspring while mothers are diving, forming a strong community that revolves around the upbringing of calves.
“They are nomadic,” explains Dr. Whitehead, “so the most important things in their lives are each other.”
Dr. Whitehead enjoys researching sperm whales because of their “fascinating and complex social lives.” He hopes the Dominica Sperm Whale Project will be able to trace how whale communities change through time.
Part of Mr. Gero’s PhD includes studying how calves acquire their dialect. Baby sperm whales babble at first, and Mr. Gero is interested in discovering how the babies’ diversity of calls gets narrowed down to the family repertoire.
More than just science
“One of the most exciting parts (of returning to Dominica) is to go down and see who’s around,” says Mr. Gero, admitting that he has “become attached to the individual whales.” For the first time, sperm whales can be studied as individuals within families, with such loveable nicknames as “Pinchy” and “Fingers.” The family that includes these two whales is recognized as “the best studied social unit of sperm whales in the world.”
Mr. Gero would like to continue working with the same groups of whales because a long-term project will offer a better understanding of their social developments. He “feels a responsibility to speak on (the whales’) behalf” and hopes to move toward conservation, while still remaining in the field of biology.
LINKS: Dominica Sperm Whale Project | Individually Distinctive Acoustic Features in Sperm Whale Codas in ...