Global warming pushes U.S. species north into Canada

Audubon Society plots bird's-eye view of winged migration

The Vancouver Sun 

BY DEBORAH ZABARENKO,REUTERS, FEBRUARY 11, 2009

 

Climate change is pushing American birds northward, with some finches and chickadees moving hundreds of kilometres into Canada, an Audubon Society study reported Tuesday.

 

Drawing on citizen observations over a 40-year period, the society's scientists found that 58 per cent of 305 widespread bird species found in the contiguous United States shifted significantly to the north. While there are many factors that can make birds move, there's no question this is caused by human-spurred global warming, according to report co-author Greg Butcher.

 Boreal chickadee. 

Photograph by: Jeremy Yancey, National Audubon Society; Reuters

 

 

"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," 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.

 

"That uniformity of movement and then a whole bunch of different tests we were able to take to correlate those movements with temperature change that make it so obvious that it's global warming is what we're dealing with here," he said.

 

All kinds of birds moved north, but more of the highly adaptable forest and feeder birds -- upward of 70 per cent -- made the move, compared with only 38 per cent of grassland species, the study found. The purple finch, pine siskin and boreal chickadee moved deep into the Canadian Boreal Forest, shifting their ranges 504, 396 and 340 km, respectively.

 

Southern-dwelling water birds, including the red-breasted merganser, ring-necked duck and American black duck, shifted their ranges northward by lesser distances. 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 despite more moderate northern temperatures because grassland habitats have been converted to human uses such as row crops, pasture and hayfields.

 

There will be fewer of these grassland birds as global warming and pressure on grasslands increases, the report said.

 

These changes in the bird world are an indicator of the impact of climate change on humans, Butcher said. "This isn't something that's going to happen in the Arctic or the Antarctic and it isn't something that's going to happen way off in the future," he said. "It's something that has been occurring over 40 years and it is disrupting the lives of birds and it's going to disrupt the lives of people."

 

Butcher said the key to combating global warming is to pass a law to cap and trade climate-warming greenhouse emissions.

 

RECENT AIRBORNE IMMIGRANTS INTO CANADA

 

Forest and feeder birds have been the most frequent new immigrants to Canada, extending their range by up to 500 kilometres. By contrast, grassland birds have not tended to move north.