Fairy-wrens vary egg size to increase survival rates

We were worried that the projected temperature extremes in Australia could lead to high chick mortality or poorer long-term survival. But we found that these birds have a surprising way to deal with this. A new study has shown that the female Superb Fairy-Wren has the ability to change the size of the eggs it lays in a biological feat which could buffer against the effects of climate change. Lead researcher Dr Naomi Langmore from The Australian National University (ANU) said the study suggested the Superb Fairy-Wren could lay larger eggs to give the chicks a better chance of survival in warmer temperatures. "Superb Fairy-Wren chicks have poorer growth rates during heatwaves," said Dr Langmore from the ANU Research School of Biology. "We were worried that the projected temperature extremes in Australia could lead to high chick mortality or poorer long-term survival. But we found that these birds have a surprising way to deal with this." Superb Fairy-Wrens are cooperative breeders, which means breeding pairs are assisted in rearing their chicks by non-breeding helpers.