Baby Birds Start Learning Parents' Calls From Inside the Egg: Study

Just like babies in utero who get accustomed to their parents' voices from inside the womb, baby birds hear and absorb their parents' chirping and singing commands while waiting to hatch from eggs, according to Australian researchers.

That's the central finding of a study led by researchers led by Sonia Kleindorfer, a professor at the BirdLab of Flinders University in Adelaide, South Australia. Kleindorfer also heads the Konrad Lorenz Research Center at the University of Vienna.

"Vocal production learning is only believed to occur in seven lineages of birds and mammals, including humans," said Kleindorfer.

Bird eggs
A new study has established that some bird embroys begin to listen and react to their parents’ songs and calls while they’re still inside their eggs. Pictured are three eggs of the Superb Fairy-Wren species. A. Katsis/Flinders Univ/Zenger

Her study examined auditory prenatal learning among embryos of three species that learn by hearing, and two that learn in other ways. The red-winged fairy-wren, the superb fairy-wren and Darwin's small ground finch are listening types. The little penguin and Japanese quail are not.

Published in the Philosophical Transactions of the Royal Society B, the research examined whether bird embryos become accustomed to other birds' calls. Scientists found that it's common among both kinds of species, and may be more widespread than anyone knew.

"This research will hopefully inspire more study into the remarkable capacity of animals to learn sound," said Kleindorfer, who described her work as "moving the time window for sound learning to the prenatal stage." She said the results could shed new light on how "early auditory experience" can determine animal behavior and information processing and even shape a bird's neurobiology.

Ground Finch
Darwin's Small Ground Finch, one of 17 such finches found on the Galapagos Islands, was one species that reacted to birdsongs from inside the egg, just as human fetuses become accustomed to their parents’ voices before they’re born. (D. Colombelli-Negrel/Flinders Univ/Zenger

Researchers measured embryos' heart rates as they heard birds chirping and singing, and used that as a proxy for whether they were responding to voices. It would be months or even years before the young birds would develop their own complex calls and songs.

Study co-author Diane Colombelli-Négrel said that "[l]ong before actual vocalization, we found that these tiny songbirds were also discriminating towards non-specific sounds and capable of 'non-associative' ... sounds," meaning noises that don't come from their own parents.

Kleindorfer said learning to produce vocal sounds is the characteristic achievement of just seven orders of animals: primates, songbirds, parrots, hummingbirds, cetaceans (whales, dolphins and porpoises), pinnipeds (seals, sea lions and walruses) and bats. Among primates, she said, "only humans can do it."

Superb Fairy-Wren
The Male Superb Fairy-Wren is pictured when it’s fully grown, at Cleland Wildlife Park in South Australia. The bird may take months or years to develop its own vocalizations, but it begins learning before it hatches. A. Katsis/Flinders Univ/Zenger

Because relatively few animals ever learn to produce meaningful sounds with their voices, it's been easy to group those that do into two groups. One is "vocal learners," those that learn to imitate another animal's voice. The other is "vocal non-learners," which make sounds without another animal to tutor them.

The BirdLab group plans to study how seven species of birds sing or call out when they're in their nests — all of them different. Each female produces combinations of different vocal sounds, they say, and some combinations are better than others at helping embryos learn while still their eggs.

This story was provided to Newsweek by Zenger News.