Climate change turning Aussie birds smaller: study

Australian birds have shrunk over the past century because of global warming, scientists have found.

Using museum specimens, researchers measured the size of eight bird species and discovered they were getting smaller in an apparent response to climate change.

Australian National University (ANU) biologist Janet Gardner said modern birds were up to four percent smaller than their forebears, a discrepancy she said was statistically significant.

"Birds, like other animals, tend to be smaller in warmer climates, because smaller bodies lose heat more quickly than larger bodies," she said.

"As a result, individuals of the same species tend to be larger near the poles and smaller near the equator."

She said the study showed that modern birds in Sydney had shrunk to the same size as those previously found in sub-tropical Brisbane, some 1,000 kilometres (620 miles) north and seven degrees of latitude closer to the equator.

Gardner said the study, published this week in the Proceedings of the Royal Society, found that the birds appeared to be adapting to global warming by becoming smaller to minimise heat stress.

The bird species examined by the researchers from the ANU and government science body CSIRO included the grey-crowned babbler, the yellow-rumped thornbill and the variegated fairy-wren.

(c) 2009 AFP