Humans are not the only creature that talk to their unborn baby. Findings of a new research have revealed that the Australian zebra finches (Taeniopygia guttata) also sing to their eggs before hatching. This particular species of bird appear to sing songs to the unborn chicks to prepare them for a warmer world driven by climate change.

The zebra finches were observed singing to their eggs when the weather is hot or above 78 degrees Fahrenheit at the end of incubation, or about five days before the eggs are supposed to hatch. Researchers also noticed that the calls become more frequent as the hatching time gets near.

Suspecting that the birds were actually talking to their eggs, Mylene Mariette and Katherine Buchanan, from Deakin University in Australia, conducted a study that recorded the incubation calls of male and female finches inside an aviary.

The researchers then played either the songs made by expectant parents before their eggs hatch in warm weather and regular calls made by adult zebra finches for eggs in an incubator.

They found that the chicks in eggs that were exposed to the so-called hot calls hatched smaller and grew slower compared with the others. The smaller size offers a survival advantage to these birds because a more compact size makes it easier for them to cool down in hot climates.

The researchers think that the songs affect the growth of the babies because they are made during the last one-third of the incubation period, during which the temperature and regulation system of the hatchlings start to develop.

The findings suggest that the zebra finches may actually be singing songs that help prepare their chicks so they are born and grow with more likelihood to survive amid warming climate.

"We demonstrate that zebra finch parents acoustically signal high ambient temperatures (above 26°C) to their embryos," the researchers wrote in their study, which was published in the journal Science on Aug. 19.

"We show that exposure of embryos to these acoustic cues alone adaptively alters subsequent nestling begging and growth in response to nest temperature and influences individuals' reproductive success and thermal preferences as adults."

The researchers also found that these hot-call birds tend to have more offspring than other birds that do not make preparatory songs for their eggs during the hot weather.

If a similar strategy is found being used by other animals, the study authors said it would suggest a survival mechanism that helps creatures better adapt to global warming.

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