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Infection blamed for 2,000 Idaho duck deaths

SALMON, Idaho (Reuters) - Two thousand mallard ducks in Idaho likely died after they ate moldy grain and contracted a fatal infection, scientists said on Thursday.

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Paul Slota, a wildlife expert with the U.S. Geological Survey’s National Wildlife Health Center, said a fungal infection known as aspergillosis was the likely killer.

“The results are certainly consistent with that diagnosis,” Slota said.

Dave Parrish, regional supervisor for the Idaho Department of Fish and Game, said further tests would be conducted.

The preliminary finding eased fears that the massive mallard die-off, which experts say is unprecedented in Idaho, was linked to bird flu.

Birds can contract aspergillosis after feeding on waste grain and silage pits during bad weather, according to the National Wildlife Health Center. Large-scale, rapid die-offs among waterfowl have chiefly affected mallards, it said.

An estimated 2,000 mallards died between Friday and Wednesday near the agricultural community of Burley, about 150 miles southeast of Boise.

State fish and game officers on Wednesday retrieved carcasses from a stream clogged with dead and dying mallards.

The stream is surrounded by farmland and a cattle feedlot, potential sources of the moldy grain, officials said.

Concerns over the deadly H5N1 flu strain and an extensive national monitoring network prompted officials to submit samples from Idaho to labs specializing in detecting avian influenza and drew the U.S. Department of Homeland Security into the investigation.

A similar aspergillosis outbreak killed 500 mallards in Iowa in 2005, the wildlife health center said. Moldy grain was the culprit in that case. The disease is not contagious.