Wednesday, March 21, 2007

Birds Shift North

More bird species in the United States are ranging farther north and even staying there for the winter in a possible sign of adaptation to global warming, ornithologists and conservation groups say.

Some indicators come from the recent Great Backyard Bird Count, which found more swallows, orioles and other common birds in uncommon locations.

"We've got Baltimore orioles in 14 states, orchard orioles in five different reports and Scott's oriole in Pennsylvania. They shouldn't be here. They should be way south," says Paul Green of the National Audubon Society, co-sponsor of the count with the Cornell Lab of Ornithology.

Scientists cannot say yet whether the birds' movements are climate-related or short-term reaction to storms, hot or cold spells, disruption of habitat or food availability. However, the results of the four-day tally performed in February are "a tempting indicator of change, which may turn out to be the early stages of the effects of changing climate on bird distribution," Green says. "We won't know for certain until we have another 20 years of data."

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Birdfreak said...

This is some interesting data but I would like to see more concrete evidence. It seems that birds have always been showing up in weird locations at weird times. I think if it was completely due to climate change there would be larger numbers of birds, not just a scattering.

frigatebird said...

Agreed. I posted it here without editorial comment, because I find it interesting, but far from conclusive. I think some of the other evidence we have seen of earlier spring arrival dates and a shifting of breeding ranges north is somewhat stronger.