Wednesday, February 11, 2009

Birds and Climate Change

Yesterday, the National Audubon Society release the following:

Birds Movements Reveal Global Warming Threat in Action
Species Wintering Farther North Show Need for Policy Change

WASHINGTON, DC, February 10, 2009—The northward and inland movement of North American birds, confirmed by thousands of citizen-observations, provides new and powerful evidence that global warming is having a serious impact on natural systems, according to new analyses by Audubon scientists. The findings signal the need for dramatic policy changes to combat pervasive ecological disruption.

Analyses of citizen-gathered data from the past 40 years of Audubon’s Christmas Bird Count (CBC) reveal that 58 percent of the 305 species that winter on the continent shifted significantly north since 1968, some by hundreds of miles. Movement was detected among species of every type, including more than 70 percent of highly adaptable forest and feeder birds. Only 38 percent of grassland species mirrored the trend, reflecting the constraints of their severely-depleted habitat and suggesting that they now face a double threat from the combined stresses of habitat loss and climate adaptation.

Population shifts among individual species are common, fluctuate, and can have many causes. However, Audubon scientists say the ongoing trend of movement by some 177 species—closely correlated to long-term winter temperature increases—reveal an undeniable link to the changing climate.

“Birds are showing us how the heavy hand of humanity is tipping the balance of nature and causing ecological disruption in ways we are just beginning to predict and comprehend,” said report co-author and Audubon Director of Bird Conservation, Greg Butcher, Ph.D. “Common sense dictates that we act now to curb the causes and impacts of global warming to the extent we can, and shape our policies to better cope with the disruptions we cannot avoid.”

Movements across all species—including those not reflecting the 40 year trend—averaged approximately 35 miles during the period. However, it is the complete picture of widespread movement and movement and the failure of some species to move at all that illustrate the potential for problems.

Purple Finch, Pine Siskin, and Boreal Chickadee have retreated dramatically north into the Canadian Boreal, their ranges moving 313, 246, and 211 miles respectively over 40 years. Continuing warming and development are predicted to have adverse impacts on the boreal forest and the species that depend on it.

Red-breasted Merganser, Ring-necked Duck, and American Black Duck, normally found in southern-tier states have all taken advantage of warmer winter waters and have shifted their ranges north by 244, 169, and 141 miles. Still, they are likely to be negatively impacted by the increased drought expected in many parts of North America as global warming worsens.

Only 10 of 26 grassland species moved north significantly, while nine moved south. Species such as Eastern Meadowlark, Vesper Sparrow, and Burrowing Owl were likely unable to move despite more moderate northern temperatures because essential grassland habitat areas have disappeared, having been converted to intensive human uses such as row crops, pastures, and hayfields. In combination, global warming and ongoing overuse of grasslands by humans will doom grassland birds to continued population declines.


The full report, images, audio and additional information can be found here.
Image by Mark Musselman

No comments: