Australasian Science: Australia's authority on science since 1938

Climate Change Makes Chicks Hatch Early

A study led by Macquarie University researchers has found that climate change is affecting how quickly bird eggs develop and hatch.

The study, published in Royal Society Open Science (www.tinyurl.com/zb9xtqo), found that hotter weather caused zebra finch eggs to start developing even before the parents had a chance to incubate them themselves.

“Typically, zebra finches will lay one egg a day for about 5 days, and will only start to incubate their eggs on the day that the last egg is laid,” explained Prof Simon Griffith, lead author of the study. “This way, all the eggs incubate and hatch at the same time in the nest, making it easier for the parents to feed and look after the chicks evenly.”

However, climate change is leading to more frequent heat waves when the birds breed, making them vulnerable.

“In the summer, we found that nests can get very hot, with recorded temperatures of up to 50°C. These birds usually like to incubate their eggs in temperatures between 36–40°C, and there is evidence suggesting that prolonged temperatures of over 40.5°C can be lethal to the developing chick embryos.

“If global temperatures were to increase, it could play havoc with the family dynamic of these birds, creating situations where a single nest contains chicks of different ages, and even causing some embryos to die if the temperatures remain too hot for a long period,” Griffith said.

The researchers point out that the warmer conditions may have both benefits and costs to the parents of the eggs. While the higher temperatures mean they might save time and energy on incubating the eggs themselves, they may also lose some of their younger and less developed chicks because they don’t preferentially feed the smallest chicks. Whether these birds can quickly adapt to the challenges of a changing climate remains to be seen.

“Future work will need to look at whether these birds, and other birds in general, are capable of adjusting to the alterations caused by climate change, particularly in the face of increasing average global temperatures and incidences of heat waves,” Griffith concluded.