Fauna Journal Entry

Birds Migrating Farther North (March 16, 2009)

Thanks to rising temperatures, migrating North American birds are heading to winter homes much farther north. An Audubon Society survey shows that more than half of the 305 bird species studied stretched their range northward over the past forty years. Average January temperatures in the United States climbed about five degrees Fahrenheit over that time span, with northern states warming the most.

On average, birds are now wintering about 35 miles farther north. The purple finch made the biggest northward jump. It now spends the winter in northern Iowa, 430 miles from its old home in southern Missouri. Wild turkey moved over 400 miles to the north, from winter homes in southern Kansas to ones along the Iowa-Minnesota border. The American robin now winters in southern Kansas, more than 200 miles from its former home along the Texas-Oklahoma border. Surprisingly, about a quarter of the species shifted their range southward despite rising temperatures.

A temperature rise isn't the only reason for range changes. Habitat destruction from urban sprawl and deforestation often forces birds to find new homes as well. But the Audubon study suggests global warming is now the main driving force behind changes in migrational routes, at least in North America.