Dolphin researchers in Sarasota Florida have found that bottlenose dolphin mothers modify their communicative whistles when they are directed at their babies. The vocalizations exhibit a higher maximum pitch, and a wider pitch range when near their babies, similar to the way that human parents use high-pitched "baby-talk" when speaking to their babies. Link to the article in Science News here.
In the first few months of life, each bottlenose dolphin develops a unique sound, or signature whistle, that acts as its name.
The dolphins shout out their own "names" in the water "likely as a way to keep track of each other," says marine biologist Laela Sayigh of the Woods Hole Oceanographic Institution in Massachusetts.
But dolphin moms seem to tweak that tune in the presence of their calves, which tend to stick by mom's side for three to six years. It's a change that Sayigh first noticed in a 2009 study published by her student. But "it was just one little piece of this much larger study," she says.
If you listen to two audio examples in the article, you'll hear a mother saying her "name" when her calf was not present, and then when her calf was present, and the latter does sound more like… baby-talk!
The study was conducted on dolphins captured from a wild population during "catch-and-release health assessments that occurred from 1984 to 2018."