Zebra finches’ ingenious ‘vocal panting’ cools them down and signals hot weather to embryos

As this latest heat wave breaks records across Australia, we have to adjust to new heat levels.

What if you could increase your heat tolerance by simply repeating the phrase, “I feel hot”?

Important points:

  • Zebra finches do a “tuning gasp” to cool off in hot weather
  • The high song is also used by parent finches to signal embryos that are still in eggs of hot weather
  • Embryos then grow less to save energy

This is what zebra finches do, according to an ongoing study by ecology researchers at Deakin University.

The zebra finch is an Australian bird with a distinctive red beak that is common in hot, dry areas of Australia, including northern Victoria.

“They’re usually in groups and very talkative. You usually hear them before you see them,” said research director Mylene Mariette from the Center for Integrative Ecology.

Mylene Mariette studies how zebra finches deal with hot weather. (Supplied: Mylene Mariette)

The original component of the study found that when zebra finches incubated their eggs in hot conditions, usually when the nest reached more than 29 degrees Celsius, they made a special, high-pitched “heat call”.

Dr. Mariette said the team found that the embryo tended to grow less when exposed to heat.

“You produce a lot of heat when you eat a lot and grow a lot,” said Dr. Mariette.

“So it is a good strategy to reduce growth when it gets very hot [for reducing heat]. “

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Dr. Mariette said they also found that embryos that reduced their growth produced more babies in adulthood.

“They were healthier because they didn’t grow as much in very hot conditions,” she said.

Dr. Mariette said the special call sounded a bit like a barbecue.

“It’s very high and very fast and follows your breathing rates,” she said.

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Vowel panting also helps parents

The team’s most recent study, published last month, found that the heat call not only served to signal embryos hot weather, but also helped keep the parent birds cool.

Dr. Mariette said that birds generally gasp to stay cool instead of sweating, and some vibrate their throats or airways to further increase the amount of water released.

“So it’s basically like dogs, and they release water to reduce body heat,” said Dr. Mariette.

“So we thought the heat call might be coming from a special form of wheezing where the birds would vibrate a path out of their airways – that would create the sound and at the same time alter their circulation to cool them down more.”

It's the first study to show how vocalization can help birds survive heat waves. It’s the first study to show how vocalization can help birds survive heat waves. (Flickr: Patrick_K59)

To test the theory, the team exposed some birds to elevated temperatures in a metabolic chamber and measured the amount of energy and water consumed while resting, panting, and calling for heat.

“We found that as they gasp from gasp to gasp and shout, they increase the amount of water they lose,” said Dr. Mariette.

“Those who say more are better able to sustain really high temperatures longer.”

Dr. Mariette said it was the first study to show how vocalization can help birds survive heat waves.

The team is now investigating whether other birds are also using “vocal panting”.

“It makes sense for zebra finches to do this because they are mostly in the hotter parts of Australia,” said Dr. Mariette.

“But there are many other small birds that probably do the same to communicate with embryos as well.”

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