[Marxism] First it was the bees, now it is the birds

[Louis Proyect <lnp3@xxxxxxxxx>]

http://www.csmonitor.com/2007/0615/p02s03-usgn.html

Common bird species in dramatic decline
A new Audubon study is one of the most comprehensive looks at 
bird-population trends in North America.
By Mark Clayton | Staff writer of The Christian Science Monitor

Boston

New data show the populations of some of America's well-known birds in a 
tailspin, thanks to the one-two punch of habitat fragmentation and, 
increasingly, global warming.

 From the heartland's whippoorwills and meadowlarks to the Northern 
bobwhite and common terns of the nation's coasts, 20 common bird species 
tracked by the National Audubon Society have seen their numbers fall 54 
percent overall since 1967, with some down about 80 percent, the group 
reported Thursday.

Most of the trouble lies with loss of bird habitat, and has for decades, 
due to expanding agriculture and suburban development. The Rufous 
hummingbird's population has fallen 58 percent due to logging and 
development in its Pacific Northwest breeding range – and in its winter 
range in Mexico. The same thing has happened to whipporwills, whose 
numbers are down 57 percent due to loss of their forest habitat. At the 
same time, scientists say changes in migration patterns due to global 
warming are emerging, too.

"Habitat loss is still the major concern," says Greg Butcher, Audubon's 
bird conservation director in an interview. "But we're also seeing 
increasing impact from large-scale problems like global warming."

Thursday's study updates and expands earlier efforts: It adds to the 
annual Breeding Bird Survey, which is done by the US Geological Survey, 
some 40 years of data gathered by thousands of volunteers from the 
Audubon Society's Christmas Bird Count program. Together, these data 
make the new study one of the most comprehensive looks at 
bird-population trends in North America.

Crows, bluebirds, mourning doves, and robins are wintering farther north 
and their populations are still robust, Dr. Butcher says. But other 
species that rely on cold climates, like the snow bunting and greater 
scaup, which breed in Alaskan and Canadian tundra, are showing signs of 
trouble. As the tundra warms, it cedes to shrubs unsuitable for the 
birds to breed, Butcher says. Scaup numbers are down 75 percent and 
bunting 64 percent, in part because these species can't go farther north 
to breed.

Although populations in some cases dip as low as 500,000 globally, none 
of the "common" bird species cited is in danger of extinction, Butcher 
notes. But their struggle mirrors a larger global trend among endangered 
migratory songbirds and tropical species.

At the current rate, global warming and destroyed bird habitat could 
lead to the significant decline or extinction of at least 400 of the 
world's 8,750 bird species, reported another new study, this one focused 
on climate-change impact. Under certain scenarios, 750 to 1,800 bird 
species could be imperiled by the year 2100, the study released earlier 
this month reported.

Most of the threatened populations are in the tropics and are in danger 
due to slashing of their rain-forest habitat – but global warming is a 
clearly a looming threat, says Walter Jetz, an assistant professor of 
biological sciences at the University of California at San Diego and 
lead author of the study.

"It's true some birds are responding already to climate change by moving 
farther north and leaving later in fall and coming back earlier," he 
says. "But there's a limit to that. At some point, there's going to be 
real trouble because of the impact and distortions on migration routes 
that have evolved over millions of years."

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