Climate change is altering the face and ecology of the planet. Ice caps are melting and sea levels are rising, while some species are headed towards extinction and others thrive.
Birds Of A Feather
But some climate change related shifts are more subtle. For example, scientists at the University of Wisconsin Madison have found that populations of winter birds visiting backyard bird feeders in the eastern United States have changed.
The researchers looked at more than two decades of data on nearly 40 species of birds, and saw that birds that used to stick to southern regions during winter have gradually moved farther north.
Birds such as cardinals, chipping sparrows, and Carolina wrens. Fifty years ago, cardinals and Carolina wrens, especially, were rare in the American east. But today they're much more common.
Changing Flight Patterns
But how can the scientists be sure that climate change is causing the shift in winter bird populations? They can't be 100% certain. But after controlling for such things as an increase in the number of bird feeders in American backyards, they concluded that climate change is the most likely cause.
When regions become warmer or colder, it's natural for animal species of all kinds to expand or shrink their territory. Winter birds, it seems, are no exception.
And any time one species replaces another in a region, the consequences for the larger ecosystem can be widespread. Time will tell how the increased presence of cardinals, chipping sparrows, and Carolina wrens in the American east will affect other animals and plants.
"Climate Change Alters Cast of Winter Birds" (EurekAlert)