Global Warming Shrinks Birds
August 17th, 2009 | 
SOME species of Australian birds are shrinking and the trend will likely continue because of global warming, a scientist said.
Janet Gardner, an Australian National University biologist, led a team of scientists who measured museum specimens to plot the decline in size of eight species of Australian birds over the past century.
The research, published last week in the British journal Proceedings of the Royal Society B: Biological Sciences, found the birds in Australia’s southeast had become between 2 per cent to 4 per cent smaller.
Over the same century, Australia’s average daily temperature rose 1.3 degrees Fahrenheit (0.7 deg C), with the sharpest increase since the 1950s.
The research concluded the birds were likely downsizing because smaller bodies shed heat faster than larger ones.
She said she suspected other Australian birds beyond the species studied were also shrinking and the trend will accelerate in the future as a result of global climate change.
‘Simply because the predictions are that the warming is going to increase over the coming decades, so you might expect this (shrinking) response to increase as well,’ Dr Gardner said.
Other studies have found similar trends of shrinking birds and mammals in Britain, Denmark, Israel and New Zealand. Dr Gardner’s bird research is the first in Australia.
Birds and other animals around the world tend to be larger closer to the poles than those nearer to the equator. Scientists believe this phenomenon is an adaptation to heat stress.
Dr Gardner’s team of researchers, from her university and the government’s Commonwealth Scientific and Industrial Research Organization, have ruled out the Australian birds’ changing insect diet over the past century as a cause for changing body size.
They found the growth rate of the birds’ feathers remained unchanged. They would have expected feather growth to have slowed if poor nutrition had stunted the birds’ growth.
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