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Archive for Tuesday, January 3, 2006

Bird experts find species shrinking

Biologists cite West Nile virus

January 3, 2006

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— Several once-common bird species are dwindling in numbers at Quivira National Wildlife Refuge, and experts believe the West Nile virus is to blame.

Seventeen researchers who conducted the annual Christmas bird count were surprised that they didn't see a single black-capped chickadee, which they say is unusual.

"When I first started doing counts, about a dozen years, we might bet 60 to 70 chickadees," said Mike Rader, who participated in the Quivira tally.

On a different count in December near Salina, researchers found no blue jays. It's the fourth year that numbers of certain species have been way down, with the timing corresponding with the discovery of the West Nile virus in the state in 2002.

"I think it's had an impact," said Max Thompson, a retired professor of biology at Southwestern College. "In 2003 we took quite a hit. The only thing everything seems to have in common is West Nile virus."

The mosquito-transmitted virus was first found in the U.S. in 1999 in New York and had spread across most of the country by 2003. Animals died wherever the virus went.

"We had hundreds of deaths in people, thousands of deaths in horses and probably millions of deaths in birds," said Nicholas Komar, a research biologist with the Centers for Disease Control and Prevention. "Some species have been extremely sensitive to the disease."

Though West Nile has killed an abundance of birds in Kansas, Thompson said it primarily has affected six species: blue jays, American crows, black-billed magpies, tufted titmice, and black-capped and Carolina chickadees.

In some areas, populations of some of those birds seem to have rebounded. Thompson said black-billed magpies, which seemed to be nearly wiped out last year, have improved from last year's count around Winfield.

Thompson and Komar said migration patterns, weather conditions and changes in habitat also might be having an impact on some of the numbers, which makes it tough to come to firm conclusions about the declining counts.

Both biologists think the worst of the West Nile virus toll has passed in the state, and populations of even the most-affected birds will return.

"It's not like these are endangered species, like California condors, where any loss could be detrimental," Komar said.

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