WASHINGTON (AP) - Experts say some birds aren't bothering to fly as far south in the winter as they have in the past. And global warming is suspected.
The purple finch, for example, has been spending its winters more than 400 miles farther north than it used to.
According to a study being released by the Audubon Society, more than half of 305 birds species in North America are spending the winter about 35 miles farther north than they did 40 years ago. They include robins, gulls, chickadees and owls.
Researchers say bird ranges can expand and shift for many reasons, including urban sprawl, deforestation and the supplemental diet provided by backyard feeders. But they say the only explanation for why so many birds over such a broad area are wintering in more northern locales is global warming.
Over the 40 years covered by the study, the average January temperature in the U.S. climbed by about 5 degrees Fahrenheit.
On the Net:
Audubon Society: www.audubon.org
The Birdwatcher's Guide to Global Warming: http://www.abcbirds.org/newsandreports/birdguide.html
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