'Baby, it's hot outside': Why birds sing to eggs

(iStock)
(iStock)

Miami - Much like parents who talk to a pregnant woman's belly, some birds sing to their eggs before they hatch, and the reason may be to prepare them for a warming world, researchers said on Thursday.

The study in the journal Science examined a peculiar habit of zebra finches, which sing to their eggs particularly when the weather is hot - above 26°C - and the end of their incubation period is near.

What could they be saying? Could it have to do with the temperature outside?

Researchers thought it might, since eggs are unaffected by outside temperatures and are kept at steady temperature of 37° C when the parents are sitting on them.

So Mylene Mariette and Katherine Buchanan of Australia's Deakin University recorded the calls and played them for eggs in an incubator.

Some eggs were played regular contact calls from adult zebra finches, while others were exposed to particular calls made by expectant parents, chirping to their eggs before they hatch in warm weather.

Those who heard these so-called hot calls grew slower and emerged smaller when they hatched than the other birds.

This compact size would present a survival advantage, because having a small body makes it easier to cool down in hot climes.

As they tracked these hot-call birds over time, researchers found they had more offspring than the other birds that did not hear the preparatory calls during the hot weather.

Researchers believe that the calls somehow affect the babies' growth, since they are delivered in the last one-third of the incubation period when the hatchlings' temperature and regulation system is starting to develop.

"By acoustically signalling high ambient temperatures to their embryos before hatching, zebra finch parents can programme the developmental trajectories of their offspring," said the study.

If such a strategy is found to exist in other animals, it would suggest a previously unknown survival mechanism to help creatures adapt to global warming, researchers said.

We live in a world where facts and fiction get blurred
In times of uncertainty you need journalism you can trust. For only R75 per month, you have access to a world of in-depth analyses, investigative journalism, top opinions and a range of features. Journalism strengthens democracy. Invest in the future today.
Subscribe to News24
Lockdown For
DAYS
HRS
MINS
Voting Booth
When a Covid-19 vaccine for under 16's becomes available, will you be taking your children to get it?
Please select an option Oops! Something went wrong, please try again later.
Results
Yes, immediately!
38% - 3223 votes
I'll wait to see how others respond
26% - 2218 votes
No, I don't think they need it
36% - 3107 votes
Vote
ZAR/USD
14.91
(+0.24)
ZAR/GBP
20.84
(+0.15)
ZAR/EUR
18.04
(+0.08)
ZAR/AUD
11.69
(-0.36)
ZAR/JPY
0.14
(+0.32)
Gold
1736.08
(+0.70)
Silver
26.75
(+0.97)
Platinum
1205.50
(+1.85)
Brent Crude
63.29
(-1.13)
Palladium
2376.00
(+1.34)
All Share
68510.75
(+1.44)
Top 40
63104.70
(+1.61)
Financial 15
12568.48
(+0.90)
Industrial 25
89150.72
(+1.21)
Resource 10
70539.82
(+2.28)
All JSE data delayed by at least 15 minutes morningstar logo