When it comes to bottlenose dolphins, people usually picture them doing tricks and displaying their intelligence. It is not everyday that one hears of bottlenose dolphins swapping babies, but that is exactly what happened in Florida.

The two bottlenose dolphins, named Pandora and Calusa, had one baby each. BBC reported that two weeks after they were born, the bottlenose dolphins swapped babies, which are also called calves.

This curious event took place at the Dolphin Research Center, a sea pen facility located in Grassy Key. Pandora, the older bottlenose dolphin, forced her younger sister Calusa to swap calves. In numerous instances, Calusa did try to get back her calf, but to no avail.

Swapping Babies Not Unique To Dolphins

A team of researchers led by Stephanie King were monitoring the two bottlenose dolphin sisters in order to look into the development of mother-calf recognition. King is from the University of Western Australia.

Co-author Kelly Jaakkola of the Dolphin Research Center said that the swapping incident between the two bottlenose dolphins "may not be as rare as one might think." Jaakkola added that female animals taking other females' offspring has been observed in numerous wild animal species.

The study on the behavior of bottlenose dolphin mothers and calves was published in the journal Marine Mammal Science. According to BBC, this study is another validation of the importance of sound in the dolphin universe.

Signature Whistles and Calves

The researchers found out that the bottlenose dolphins quickly increase their unique "signature whistles," BBC reported. The bottlenose dolphins whistled up to five times more than what was usual.

Lead researcher King said that it was called "vocal imprinting" wherein the baby dolphin or the calf imprints on its mother's signature whistle. "It's an important learning phase where the calf learns to recognise (sic) its mother, and it's important this happens quickly before mother-calf separations occur," King told BBC.

King added that calves learn signature whistles and are not born with it. Before the calves learn their own signature whistles, they find their mothers by closely listening to their mother's unique signature whistles.

A separate study, conducted by King, Jaakkola, Emily Guarinoa, Loriel Keatona and Linda Erb showed that the signature whistles of bottlenose dolphins are vital in mother-calf reunions and not just in establishing identity. It was published in the journal Behavioural Processes. Guarinoa, Keatona and Erb are also from the Dolphin Research Center.

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