Duck die off in Idaho prompts questions

By Laura Zuckerman

SALMON, Idaho (Reuters) - Officials scrambled on Wednesday to determine what has caused the deaths of thousands of mallard ducks in south-central Idaho near the Utah border.

Although wildlife experts are downplaying any links to bird flu, they have sent samples to government labs to test for the deadly H5N1 flu strain, among other pathogens.

Officials with the federal Bureau of Homeland Security have been also called in to help with the probe.

"We think the possibility of avian flu is very remote but we're not ruling anything out at this point in time," said Dave Parish, regional supervisor for the Idaho Department of Fish and Game. "We want to make sure all the bases are covered."

Wildlife officials are calling the massive die-off alarming, with the number of dead mallards rising from 1,000 on Tuesday to more than 2,000 by Wednesday afternoon. "We've never seen anything like this -- ever," Parrish said.

A hunter alerted state conservation officials after finding a handful of dead ducks along a creek near Burley, about 150 miles southeast of Boise, on Friday.

By Wednesday, dead and dying birds clogged sections of the stream and littered its banks. Officials have posted signs warning hunters and others not to touch or eat the birds until a cause of death has been identified.

Preliminary findings by state veterinarians suggest the mallards succumbed to a bacterial infection, officials said. They said it was unclear why a similar outbreak had never before occurred in Idaho.

SIMILAR EVENT IN IOWA LAST YEAR

On Wednesday, officials outfitted with protective gear were gathering hundreds of mallard carcasses. Wildlife managers said the birds will be incinerated.

The only mallard die-off roughly equivalent in recent years happened in Waterloo, Iowa in 2005, when 500 ducks died from a fungus they contracted by eating moldy grain, according to a report by the U.S. Geological Survey's National Wildlife Health Center.

The center's Kathryn Converse, a wildlife disease specialist, said early clues suggest the outbreak in Idaho is not linked to insecticides applied to surrounding croplands because it is not affecting other bird species or predators feeding on the dead ducks.

Mallards are the most common duck species in the United States, with populations nationwide. Most mallards that winter in Idaho originate from Alberta, Canada, with a smaller percentage from the Northwest Territories, said Tom Keegan, regional wildlife manager with Idaho Fish and Game.

Although the magnitude and the pace of the die-off is unusual, officials said, migratory birds and other wild animals are more likely to get sick when large numbers congregate in small areas.

That can happen to mallards in the winter, when many of the waterways they depend upon are frozen.

Compounding the seasonal phenomenon is the ever-shrinking habitat available to wildlife because of sprawling development and expanding farm operations.

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