Zebra finches sing “heat warnings” to eggs before hatching
Australia: In Australia’s hot woodlands, adult zebra finches make rapid peeping “heat calls” when temperatures rise. New research shows they sing these calls to eggs still in the nest. The sound gives unhatched chicks a forecast of the heat waiting outside the shell.
The calls trigger genetic changes in the embryo’s brain, especially in the hypothalamus that controls metabolism and heat response. A study published June 11 in Journal of Experimental Biology found this reprogramming helps chicks handle high temperatures after hatching.
Scientists at Deakin University and Clemson University built on earlier work. Ten years ago they found chicks exposed to heat calls grew slower, preferred warmer nesting spots, and seemed better adapted to heat. The new study explains how: the song changes brain activity and mitochondrial function. Chicks that heard the calls produce more ATP and less heat, reducing cellular damage in hot conditions.Parents only use the calls above 26°C, and only in the last 5 days before hatching. Lab tests confirmed the effect. Eggs played the heat call hatched chicks that stayed smaller in hot nests. As adults, females that heard the calls produced more fledglings.
For zebra finches living in deserts that swing from -5°C to 46°C, the song is an adaptation. It’s the first known case of animals using sound to alter offspring growth, development and reproductive success before birth.
