Warming Changes Where Birds Wait Out Winter
Wx and the City
A report released yesterday by the National Audubon Society indicates that 177 bird species in the United States have experienced northward or inland shifts in where they spend winter (or "overwinter") over the past 40 years.
Audubon cites warmer winter temperatures -- specifically, a rise of more than five degrees Fahrenheit in average January temperatures in the lower 48 States during the past four decades -- as the overarching cause of these shifts. Rising winter temperatures make northern latitudes more habitable for species commonly found farther south.
Have any mid-Atlantic bird species been affected by warmer winters? Keep reading...
The report suggests that other factors can change a species' geographical range, including habitat loss due to development, but that the consistency in the direction of movement and rates of population change are most likely correlated to consistently warming temperatures.
"... a wide variety of other factors play a contributing role and explain why a minority of species showed no movement or even shifted southward," the report states. "However, the correlation between shifting ranges and winter temperature trends cannot be ignored in explaining some of the widespread and directionally consistent movements seen among U.S. bird species."
Among the biggest movers nationwide are the Wild Turkey (408 miles) and the American Robin (206 miles).
How have birds in the D.C. area been affected? Several species common to the mid-Atlantic region have experienced shifts in their winter ranges, including the Snow Goose (217.1 miles), Eastern Bluebird (114.5 miles) and Cedar Waxwing (189.2 miles).
A state-by-state map displays a complete list of affected species in the lower 48 States and their estimated shifts over the 40-year period. The 20 species that have experienced the largest shifts, as well as the direction of these shifts, can be found here.
The report is based on the tracking of land birds, water birds and coastal species by scientists and trained citizen volunteers through Audubon's Christmas Bird Count study since 1966. The study monitors 2,000 locations nationwide for two weeks over the holiday season every year.
The report also says that new research indicates that in California, massive shifts over the next 100 years in the geographical ranges of all bird species in will be "caused wholly or in part by the effects of climate change."
To find out how to help scientists monitor bird species in your neck of the woods, including the Christmas Bird Count and the Great Backyard Bird Count (happening Presidents Day weekend, Feb. 13-16) check out Audubon's citizen science page.
| February 11, 2009; 11:05 AM ET
Categories: Climate Change, Environment, Nature, Posegate, Wx and the City
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