Migratory Birds Brought Bird Flu To Idaho

Feb 9, 2015

The U.S. Department of Agriculture says the avian influenza found in a flock of chickens in Parma last month, came to Idaho from Southeast Asia.

Idaho’s State Veterinarian Bill Barton says the sickness was likely carried here by wild waterfowl like ducks and geese. Avian influenza is fairly common in wild birds. While Barton says they have a high tolerance for the virus, it's often lethal in domestic poultry. So far, no bird flu strain that has been found in Idaho is harmful to people.

“With the migratory routes of wild birds in Asia, and then the migratory routes from Asia over to the U.S, there’s a lot of co-mingling of birds,” Barton says. “Among poultry and wild birds, avian influenza is easy to pass from one bird to another.”

Barton says bird flu is most commonly transmitted through feces. A migrating bird could easily get the virus by stepping in its Asian neighbor’s waste and later pass it to an Idaho chicken through its own.

He says the strain of bird flu found in Idaho likely came down what’s known as the 'Pacific Flyway.' That’s a migratory path from the Arctic, down through the western U.S. and beyond.

Jeff Knetter, Idaho Fish and Game’s top bird expert, says that means there are a lot of suspects for who could have brought bird flu to Idaho.

“There are a variety of species that sort of co-mingle along the Bering Strait, northern Alaska or even northern Russia," he says. "Those could be snow geese, they could be northern pintail, mallards, green winged teal species, American wigeon - all species that you can see in the Treasure Valley.”

In Alaska and Russia, the Pacific Flyway overlaps with another huge migration route, the East Asian – Australasian Flyway. So Birds that winter in Cambodia might roost next to birds that winter in California and pass through Parma during their travels.

Knetter says researchers know of one group of snow geese that breeds on Russia’s Wrangle Island, winters in California’s Central Valley and stops in southwest Idaho on its way north. He says there are between 50,000 and 60,000 snow geese and 30,000 to 40,000 greater white fronted geese that pass through southwestern Idaho each year.

Knetter says 10 to 15 years ago, neither of these species passed through this part of the state. But their migration patterns have changed. And, even though these geese are coming through in large numbers now, Knetter says you may not have noticed them. They tend to steer clear of urban areas, unlike the Canada geese found all over the Boise area.

Find Adam Cotterell on Twitter @cotterelladam

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