Shifting Birds

A study carried out by the Audubon Society has discovered that climate change is pushing North American birds northward, with some finches and chickadees moving hundreds of miles into Canada.

As the temperatures across the US have gotten warmer, the birds are spending their winters farther north than they used to. The study found more than half of 305 bird species in North America are wintering about 35 miles further north than they did 40 years ago.

Some species, such as the purple finch and boreal chickadee, spend their summers in the forests of Canada and fly south into the US for the winter. Climate change could be playing a role in why they are not flying as far south as they used to, and are no longer as common as they were in states like Maine, Vermont and Wisconsin.

Pine Siskin

Pine Siskin

The purple finch, pine siskin and boreal chickadee moved deep into the Canadian boreal forest, shifting their ranges 313, 246 and 211 miles, respectively. Previous studies of breeding birds in Great Britain and the eastern US have detected similar trends, but the Audubon study covers a broader area and many more species.

“There’s a thousand things that cause birds to change their range, and so if you do a study of a whole bunch of birds, you’ll see some moving north, some moving south, some moving west,” report co-author Greg Butcher said. “What was real surprising about this study is to see the birds moving so uniformly in one direction.”

Scientists were able to relate this movement with temperature changes from 1966 through 2005.

All kinds of birds moved north, but more of the highly adaptable forest and feeder birds — upward of 70% — made the move, compared with only 38% of grassland species.

Only 10 of 26 grassland species made significant moves north. Birds including the eastern meadowlark, vesper sparrow and burrowing owl may have been unable to move despite more moderate northern temperatures because grassland habitats have been converted to human uses such as row crops, pasture and hayfields.

Unlike most global warming stories in the media, this is not something predicted to happen in the future. It’s been happening for over 40 years. And provides yet another reason why it is vital to save our boreal forests, natural grasslands and wetlands.

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