Female dolphins change their whistle when talking to calves (Credit: Sarasota Dolphin Research Program/ NMFS MMPA Permit 20455)

When it comes to brainpower, bottlenose dolphins are second only to humans. The intelligent animals are known to use tools, help fellow dolphins in distress, and even prepare their food to make it more palatable. Now, a new study has found that just like humans, dolphin moms change their voices when "talking" to their young ones.

Every bottlenose dolphin has a unique whistle. Similar to a human name, it allows them to identify themselves when communicating with other dolphins. But researchers at Florida's Sarasota Dolphin Research Program found that female dolphins alter their signature sound when they are around their calves.

Marine biologist Laela Sayigh first noticed dolphins using "motherese," or baby talk, in 2009. However, the researcher did not get an opportunity to investigate it further until recently. For the study, Sayigh and her team analyzed audio recordings of 19 female dolphins with and without calves. The sounds were captured during catch-and-release health checks of dolphins in Sarasota Bay from 1984 to 2018. The scientists randomly selected 20 whistles from each individual. They found that the mothers used a wider range of pitches around their calves. They were either higher than their regular whistles or slightly lower.

The researchers revealed their findings in the journal Proceedings of the National Academy of Sciences on June 16, 2023. They are unsure why dolphins change their voices when talking to their offspring. In humans, the higher pitch is believed to hold the infant's attention and develop their vocal skills.

Researchers think the "baby talk" may enhance the bond between mother and calf (Credit: sarasotadolphin.org/ CC-BY-SA-2.0)

But dolphin calves establish their unique calls by age two. Hence, it is unlikely that the mother is teaching them how to pronounce their "name." Sayigh speculates that the pitch change helps the calves identify the whistles specifically directed at them, strengthening the bond between mother and child.

The researchers say that the purpose of using "motherese" may be different in humans and dolphins. However, the study could help scientists understand the evolution of language in vocal species, including humans.

Resources: Science.org, theguardian.com, cbsnews.com