A climate-related decline in Canberra's population of superb fairywrens may have worrying implications for other Australian birds, researchers believe.

Scientists who have monitored the species since the late 1980s at the Australian National Botanic Gardens have recorded the largest winter mortality rate of the tiny birds.

Associate Professor Damien Farine attributed the die-off to sudden cold snaps following months of above-average temperatures.

"What happened in Canberra was that it was unseasonably warm up until the end of May, and then winter hit very suddenly," said Assoc Prof Farine of Australian National University's Research School of Biology.

"The first major wave of mortality that we saw was in that two weeks following that initial drop in temperature."

In July, the same pat

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