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North American birds on the decline

Nearly a third of native bird species - even common ones - are seeing striking losses, says a survey.

By Staff writer of The Christian Science Monitor / December 2, 2004



Nearly two centuries ago, vast herds of buffalo were almost wiped off the face of America's great plains by settlers. Today it's the prairie chicken that's getting plucked.

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Once plentiful like the buffalo, the prairie chicken was dubbed the "fool's hen" because it was so easy to shoot. Even so, the delectable but hardy species survived. As recently as the 1980s, healthy numbers could be found "booming" their songs across the plains.

But a new survey shows that the greater prairie chicken species is in trouble. Since 1966, its population has fallen 78 percent. Fewer than 700,000 individual birds remain. It's a fate shared by many species - from the cerulean warbler to the chimney swift to the northern bobwhite.

In a striking trend that spans North America's key ecosystem regions - grassland, shrubland, forest, wetland, and urban - almost a third of 654 bird species native to North America are in "statistically significant decline," according to a first-ever "State of the Birds" report unveiled last month by the Audubon Society.

"We've painted a picture people didn't know before - that there's a big fraction of our bird populations that are facing serious problems," says Greg Butcher, a wildlife biologist and author of the report, which draws on decades' worth of data from major bird population surveys.

Grassland species are in the most trouble, with 19 of 27 species analyzed - 70 percent - in significant decline since 1966. But what's affecting the prairie chicken and other grassland species is not a single cause - such as too much hunting - but instead a "perfect storm" of habitat loss, predators, and changing farming and ranching practices, researchers say.

Ironically, the resurgence of some predator birds, such as hawks, have made it harder for prairie chickens to find a peaceful home on the range. More intense cattle grazing, proliferating power lines, roads, fencing, housing, and shopping malls - even huge new electrical wind generators - have added to the pressure.

The lesser prairie chicken, in rapid decline like the greater prairie chicken, instinctively resists nesting anywhere near trees or man-made structures - especially tall towers or buildings, where birds of prey can perch and spot them below, according to recent studies by Kansas State University biologists.

"One of the biggest threats on the horizon is wind farms," says Steve Sherrod, executive director of the George Miksch Sutton Avian Research Center in Bartlesville, Okla. "These wind farms are billed as green, but they're a huge threat to the prairie nesting species."

Other grassland birds are similarly affected. The bobolink, for instance, nests in hayfields and northern grasslands of the United States. But more frequent haying, overgrazing, and other man-made changes have combined to cut its population in half to about 11 million, the report says.

Similar declines show up in other ecosystems. The northern bobwhite, a common bird with a call familiar to millions, prefers shrublands - sagebrush and chaparral - which span 20 percent of the Lower 48 states. Yet conversion of shrublands to grazing and ill-timed burning of farm fields have cut its numbers by more than two-thirds to 9 million.

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