Dozens of Idaho Department of Fish and Game workers and volunteers at the weekend retrieved and incinerated carcasses of snow geese found near bodies of water and a wildlife management area in the eastern part of the state, said agency spokesman Gregg Losinski.
Avian cholera is believed to be the culprit in the deaths mostly because of the way the birds died, he said.
“Basically, they just fell out of the sky,” said Losinski.
He said biologists were awaiting results from a state wildlife lab to confirm the birds died of the highly contagious disease, which is caused by bacteria that can survive in soil and water for up to four months.
Humans face a small risk of contracting the disease but the more immediate threat is to wildlife in the vicinity of contaminated carcasses, Losinski said.
About 20 bald eagles were seen near areas where snow geese carcasses littered the ground but a lengthy incubation period makes it unclear if the eagles were infected and would carry the ailment elsewhere, said Losinski.
It was not known where the snow geese – named for their white plumage and for breeding in the far northern corners of Alaska, Canada, Greenland and Siberia – contracted avian cholera during a migration that saw them wing north from wintering grounds in the American Southwest and Mexico, he said.
Outbreaks like the one found affecting the migrating snow geese in Idaho occur periodically in the United States and elsewhere, Losinski said.
Avian cholera is the most important infectious disease affecting wild waterfowl in North America, according to the U.S. Geological Survey.