William Atkins
Sunday, 14 March 2010 01:33
Science -
Biology
Page 1 of 4
A Swiss-U.S. study has found that over the last half century North American birds have become smaller by about 1.3% in mass. The fairly rapid evolution to a more compact size is concluded to be caused by climate change.
The authors—Josh Van Buskirk (Institute of Zoology, University of Zürich, Switzerland), and Robert S. Mulvihill and Robert C. Leberman (both from the Powdermill Avian Research Center, Carnegie Museum of Natural History, Pennsylvania, U.S.A.)—have published the results of their work in the ecological journal
Oikos.
The title of their paper is “
Declining body sizes in North American birds associated with climate change” (DOI: 10.1111/j.1600-0706.2009.18349.x). It was published online on March 2, 2010.
The researchers state, within their paper, climate change, continuing warming of the planet, that has come over the Earth has caused relatively rapid changes in the
“phenology and geographic distributions of many plants and animals.”They found that, since 1961, migrating birds captured and studied from the Carnegie Museum’s Powdermill ringing station—a banding station in western Pennsylvania, in the United States—have had
“steadily decreasing fat-free mass and wing chord.” They studied 486,000 individual birds, from 102 species, which were banded from 1961 to 2007. They found that the birds are getting small in size (weight) and growing shorter wings.
Specifically, according to the March 12, 2010 BBC Earth News article “
Climate change 'makes birds shrink' in North America,” the following findings were concluded:
•
“Of 83 species caught during spring migration, 60 have become smaller over the 46 year study period, weighing less and having shorter wings.”•
“Of the 75 species migrating in autumn, 66 have become smaller. In summer, 51 of 65 breeding species have similarly reduced in size, as have 20 out of 26 wintering species”Page two continues with comments from Dr. Buskirk, one of the researchers of the bird study.
