March 1, 2012
Unique Whistles Allow Dolphins To Greet Each Other
Marine biologists have discovered that bottlenose dolphins use whistles to greet other members of their species.
The researchers in Scotland said they made recordings of dolphins swimming in St. Andrews Bay in the summers of 2003 and 2004 by using hydrophones.They said when the group of dolphins met up, they swapped whistles that outwardly sounded the same.
"The whistle exchange is more of a greeting ceremony that communicates a friendly intention and is perhaps not needed to identify the group after the first introduction," co-author Vincent Janik of the University of St. Andrews Sea Mammal Research Unit, told Discovery News.
The team analyzed the whistles and found that they were in fact individual signatures, and were never matched or copied by other dolphins.
"Signature whistle exchanges are a significant part of a greeting sequence that allows dolphins to identify conspecifics [members of the same species] when encountering them in the wild," the researchers wrote in the British journal Proceedings of the Royal Society B.
The researchers wrote in the journal that the whistles were heard in 90 percent of the meetings.
Other whistles observed could be about agreeing roles to hunt for food or identifying individuals for socialization.
The latest study is the first to show how free-ranging dolphins in the wild use these whistles at sea.
The finding adds to existing evidence that dolphins posses one of the most sophisticated communication systems in the animal kingdom.
"In my mind, the term 'language' describes the human communication system; it is specific to us," Janik told Discovery News. "It is more fruitful to ask whether there are communication systems with similar complexity. I think the dolphin system is probably as complex as it gets among animals."
They said the one whistle came from what seemed to be the leader of the group, giving the dolphins the "ok" to join up with the other group.
This individual could be an older dolphin that was elected as a "spokesman" to represent the entire group during meetings, Janik said.
Dolphins use sound and echolocation in the ocean for their communications rather than visual, scent or other signals.
A dolphin is able to hear the whistle of another dolphin over a distance of about six miles, despite a noisy background.
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