Red-winged blackbird falls victim to climate change
Numbers of the red-winged blackbird have fallen since 1972
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Tuesday, 14, Nov 2006 01:18
A red-winged blackbird population in Ontario, Canada, has fallen by 50 per cent in the past 25 years due to global warming, a US researcher has claimed.
Patrick Weatherhead, an ecologist at the University of Illinois, studied data about the bird's numbers alongside climate records for the same period.
He found a direct correlation with the North American oscillilation (NAO), the dominant cause of changes in the winter climate of the north Atlantic region, which ranges from central North America to Europe and much of northern Asia.
As the NAO continued on an upward trend for the past 25 years, the numbers of the red-winged blackbird fell.
The data also revealed that global warming appears to be affecting the bird's breeding habits.
"Although the breeding season started at the same time each year, it lasted longer," Dr Weatherhead explained. "The birds appear to be interpreting the longer season as the end of the season lasting longer, when more female eggs typically hatch, so that shift has affected the population sex ratio."
He concludes that although what will happen to the bird in the future is unclear, if the climate trends continue then there are likely to be further changes in population size.