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 91裸聊视频� akin to calling out their own name.

91裸聊视频淭hey use these whistles to keep track of each other. They91裸聊视频檙e periodically saying, 91裸聊视频業91裸聊视频檓 here, I91裸聊视频檓 here91裸聊视频�,91裸聊视频� said study co-author Laela Sayigh, a Woods Hole Oceanographic Institution marine biologist in Massachusetts.

When directing the signal to their calves, the mother91裸聊视频檚 whistle pitch is higher and her pitch range is greater than usual, according to the study published in the journal,

91裸聊视频淭hat was true for every one of the moms in the study, all 19 of them,91裸聊视频� 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 Florida91裸聊视频檚 Sarasota Bay to record their signature whistles. That included years when they had calves and when they didn91裸聊视频檛 91裸聊视频� dolphin calves stay with their mothers for an average of three years in Sarasota, and sometimes longer. Fathers don91裸聊视频檛 play a prolonged role in parenting.

91裸聊视频淭his is unprecedented, absolutely fantastic data,91裸聊视频� said Mauricio Cantor, an Oregon State University marine biologist who was not involved in the study. 91裸聊视频淭his study is the result of so much research effort.91裸聊视频�

Why people, dolphins or other creatures use baby talk isn91裸聊视频檛 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 offspring91裸聊视频檚 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 don91裸聊视频檛 know if dolphins also use baby talk for other exchanges 91裸聊视频� or whether it helps their offspring learn to 91裸聊视频渢alk91裸聊视频� as it seems to do with humans.

91裸聊视频淚t would make sense if there are similar adaptations in bottlenose dolphins 91裸聊视频� a long lived, highly acoustic species,91裸聊视频� where calves must learn to vocalize many sounds to communicate, said Frants Jensen, a behavioral ecologist at Denmark91裸聊视频檚 Aarhus University and a study co-author.

Another possible reason for using specific pitches is to catch the kids91裸聊视频� attention.

91裸聊视频淚t91裸聊视频檚 really important for a calf to know 91裸聊视频極h, Mom is talking to me now91裸聊视频� __ versus just announcing her presence to someone else,91裸聊视频� 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 Institute91裸聊视频檚 Science and Educational Media Group. The AP is solely responsible for all content.

Christina Larson, The Associated Press

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