Did you know that birds sing to their eggs?

male and female Zebra finches

Researchers have long known that baby birds can hear through their eggs, allowing them to imprint things like who their mother is. A new study published recently in Science demonstrates that certain zebra finches can change their young’s growth and behaviour in adulthood. The study showed that the songs zebra finches sing to their eggs late in development may give the young a head start in dealing with warm weather once they hatch. The implications are that birds feeling the increased heat associated with climate change may be able to give their offspring an early weather advisory through the eggshell—in turn helping the baby birds prepare for the forecast.

“This acoustic signal is potentially being used to program the development of offspring,” says Kate Buchanan, an associate professor of animal ecology at Deakin University in Australia and the senior author of the new paper. “Hearing the call affects your rate of growth relative to the temperature that you experience. “Animals have very subtle ways of inferring how the environment is likely to change, and (being able) to develop and adapt accordingly,” she added. “We’re only looking at the tip of the iceberg in terms of what we recognize so far… It is quite paradigm-shifting.”

While researchers are just starting to understand this behavior, the implications may provide a rare instance of good news in terms of the ways animals can subtly adapt to a changing climate, she says.

Zebra finches nesting

According to the Smithsonian, Zebra finches live in the harsh, dry scrub environment of the Australian Outback. The females do most of the incubation, and the birds often mate for life, Buchanan says. The males are brightly colored, and the zebra finches are notorious songsters, a trait that makes them popular with pet owners and researchers, who have studied the pear-sized birds’ speech patterns ad nauseam. The researchers managed to find a new sound that nobody else had noticed before—it only popped up during the last few days of egg incubation. The birds only made this special noise when the temperature climbed above 78°F.

The Smithsonian writes:

Researchers then took finch eggs into an incubation chamber at a constant temperature (they replaced the ones in the nest with false eggs) and played back different sounds to two different groups of eggs during the last three to five days of incubation. Once the birds hatched, they placed them back in the outdoor finch nests, and found that their growth and development differed based on whether or not they had heard the sounds while still in the egg.

baby birds singing for food

When the temperature in the nest after hatching was higher, nestlings exposed to the incubation calls while in the egg tended to be smaller on average than hatchlings exposed to normal socialization sounds. Warmer temperatures have been correlated with smaller birds in many other species; being smaller may give them an advantage, because body size impacts thermoregulation and can reduce damage to the bird’s molecules.

Mark Hauber, a professor of animal behavior at the City University of New York, says that the paper is shocking, with major implications on how we understand early embryonic development and auditory learning in birds. “It’s so novel. It’s going to open up a brand new field of research,” he says.

the fairy wren

Hauber contributed to some of the only other research on incubation calling, in which the authors found that fairy wrens train their chicks to make certain sounds when born so the parents can distinguish them from cuckoos, a parasitic bird that lays eggs in other birds’ nests before skipping out on the childcare struggle. Cuckoos don’t have the brain mechanism to learn to identify a song, so fairy wrens use incubation calling as a strategy to avoid raising the parasitic cuckoos.

“What was important about some of the more recent work is it showed that much of this learning already takes place inside the egg,” Hauber says.

Nina Munteanu is a Canadian ecologist / limnologist and novelist. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s bilingual “La natura dell’acqua / The Way of Water” was published by Mincione Edizioni in Rome. Her non-fiction book “Water Is…” by Pixl Press (Vancouver) was selected by Margaret Atwood in the New York Times ‘Year in Reading’ and was chosen as the 2017 Summer Read by Water Canada. Her novel “A Diary in the Age of Water” will be released by Inanna Publications (Toronto) in May 2020.