21 August 2008

Birds can’t keep up with climate change

Agence France-Presse
The habitats of wild bird species are shifting in response to global warming, but not fast enough to keep pace with rising temperatures, according to a study.
Birds

The heat is on: Try as they might, birds in France are struggling to keep up with the changing climate. Credit: iStockphoto

PARIS: The habitats of wild bird species are shifting in response to global warming, but not fast enough to keep pace with rising temperatures, according to a study.

Researchers in France also found that the delicate balance of wildlife in different ecosystems is changing up to eight times more quickly than previously suspected, with potentially severe consequences for some species.

Growing mismatch

“The flora and fauna around us are shifting over time due to climate change,” said lead author Victor Devictor, of the National Museum of Natural History in Paris. “The result is desynchronisation. If birds and the insects upon which they depend do not react in the same way, we are headed for an upheaval in the interaction between species.”

These “mismatches” are likely to become greater over time, and could eventually threaten some birds with extinction, he added.

The study is published this week in the British journal Proceedings of The Royal Society B.

It shows that the geographic range of 105 birds species in France – accounting for 99.5 per cent of the country’s wild avian population – moved north, on average, 91 km from 1989 through 2006. Average temperatures, however, shifted northward 273 km over the same period, nearly three times farther.

The fact that some birds have responded to climate change had already been noted in individual species. What surprised Devictor and his colleagues was that the shift held true for virtually all birds in France, and that the gap with the rising temperatures was big and getting bigger.

“The response is faster than we thought, but it is still not fast enough to keep up with climate change,” he said.

Breeding bird survey

Earlier studies looked at the impact of global warming by comparing “snapshots” taken years or decades apart – of the range across which a given species lived. But trying to define the outer boundary of a shifting habitat is extremely difficult because data is, by definition, scarce.

Devictor took another approach, taking advantage of France’s Breeding Bird Survey, which has gathered data collected by hundreds of ornithologists from more than 1,500 well-defined plots since 1989. This made it possible to look at the entire distribution of a species over a continuous period, he explained.

The northward shift of most species “is most likely changing at its maximal possible rate, which is insufficient to catch up to climate change,” Devictor said. “This discrepancy may have profound consequences on the ability of species to cope with climate change in the long run.”

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