You know instantly when someone is speaking to an infant or small child. It turns out that dolphin mothers also use a kind of high-pitched baby talk.

found that female bottlenose dolphins change their tone when addressing their calves. Researchers recorded the signature whistles of 19 mother dolphins in Florida, when accompanied by their young offspring and when swimming alone or with other adults.

The is a unique and important signal B次元官网网址� akin to calling out their own name.

B次元官网网址淭hey use these whistles to keep track of each other. TheyB次元官网网址檙e periodically saying, B次元官网网址業B次元官网网址檓 here, IB次元官网网址檓 hereB次元官网网址�,B次元官网网址� said study co-author Laela Sayigh, a Woods Hole Oceanographic Institution marine biologist in Massachusetts.

When directing the signal to their calves, the motherB次元官网网址檚 whistle pitch is higher and her pitch range is greater than usual, according to the study published in the journal,

B次元官网网址淭hat was true for every one of the moms in the study, all 19 of them,B次元官网网址� said biologist Peter Tyack, a study co-author from the University of St. Andrews in Scotland.

Obtaining this data was no simple feat. Over more than three decades, scientists placed special microphones multiple times on the same wild dolphin mothers in FloridaB次元官网网址檚 Sarasota Bay to record their signature whistles. That included years when they had calves and when they didnB次元官网网址檛 B次元官网网址� dolphin calves stay with their mothers for an average of three years in Sarasota, and sometimes longer. Fathers donB次元官网网址檛 play a prolonged role in parenting.

B次元官网网址淭his is unprecedented, absolutely fantastic data,B次元官网网址� said Mauricio Cantor, an Oregon State University marine biologist who was not involved in the study. B次元官网网址淭his study is the result of so much research effort.B次元官网网址�

Why people, dolphins or other creatures use baby talk isnB次元官网网址檛 certain, but scientists believe it may help offspring learn to pronounce novel sounds. Research dating back to the 1980s suggests that human infants may to speech with a greater pitch range. may alter their calls to attract and hold offspringB次元官网网址檚 attention. And Zebra finches and slow down their songs to address chicks, perhaps making it easier to learn birdsong.

For the dolphin study, the researchers focused solely on the signature call, so they donB次元官网网址檛 know if dolphins also use baby talk for other exchanges B次元官网网址� or whether it helps their offspring learn to B次元官网网址渢alkB次元官网网址� as it seems to do with humans.

B次元官网网址淚t would make sense if there are similar adaptations in bottlenose dolphins B次元官网网址� a long lived, highly acoustic species,B次元官网网址� where calves must learn to vocalize many sounds to communicate, said Frants Jensen, a behavioral ecologist at DenmarkB次元官网网址檚 Aarhus University and a study co-author.

Another possible reason for using specific pitches is to catch the kidsB次元官网网址� attention.

B次元官网网址淚tB次元官网网址檚 really important for a calf to know B次元官网网址極h, Mom is talking to me nowB次元官网网址� __ versus just announcing her presence to someone else,B次元官网网址� added Janet Mann, a marine biologist at Georgetown University, who was not involved in the study.

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Follow Christina Larson on Twitter at: @larsonchristina

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical InstituteB次元官网网址檚 Science and Educational Media Group. The AP is solely responsible for all content.

Christina Larson, The Associated Press

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