An outbreak of highly pathogenic bird flu in wild birds and backyard flocks has killed thousands of birds across the state, according to Oregon wildlife and agriculture officials.
The disease, commonly known as bird flu, has been detected in almost every county in Oregon. Its current strain is particularly deadly to wild birds, which are dying in greater numbers than in previous outbreaks.
The number of backyard flocks – which include chickens, ducks and other domestic birds – that have been affected has also been far greater than in recent outbreaks. While turkeys are particularly susceptible to the disease, only a handful have died locally since Oregon is not a turkey-producing state, officials said.
Sick birds act as if they are drunk. They are uncoordinated and lethargic; they move about, swim in circles and fly against the facades of houses. Those with symptoms usually die within 72 hours.
“It’s really serious,” said Ryan Scholz, a state veterinarian with the Oregon Department of Agriculture.
Bird flu viruses are naturally present in the environment, and bird flu does not always cause death or even disease in birds. Some birds, such as mallards, have developed immunity to the disease, even to its highly pathogenic strains. They show no symptoms, but they spread the disease, most often through feces.
The virus typically arrives in the United States from Europe or Eurasia, carried by waterfowl that travel thousands of miles. Birds spread disease whenever they land to rest.
Deadly strains of bird flu have increased in recent years. Highly pathogenic avian influenza has devastated wild birds and the poultry industry across the world. The virus is now endemic in Europe and Asia.
This year could prove to be even deadlier than usual. The virus usually disappears in dry, warm weather, as low pathogenic strains of the disease naturally outcompete it. This happened in 2014-15, the last major outbreak in the United States in domestic birds.
But birds haven’t stopped getting sick this summer in the Pacific Northwest. They continued to die off during the warmer months and well into the fall – an anomaly from how the virus usually works.
Over the past few weeks, wild birds have been falling ill and dying from the Fernhill Wetlands to Forest Grove to the Tualatin River Wildlife Refuge to the Willamette Valley Wildlife Refuges. It’s impossible to know exactly how many wild birds were affected, said state wildlife veterinarian Colin Gillin.
“If I said it was in the thousands, that would be an underestimate,” Gillin said.
About 17% of waterfowl that have been tested have tested positive for the disease, which is “a substantial number,” Gillin said. The species currently most affected is Cackling’s goose, but the disease also kills many bald eagles, hawks, owls and herons.
Songbirds and wild turkeys weren’t affected, Gillin said, because they don’t usually interact with waterfowl and aren’t a scavenger species.
There are also concerns for snow geese after nearly 400 sick or dead geese were found at Wiser Lake in western Washington a few days ago and several tested positive for the flu avian. Many of the dead birds were snow geese. These birds are just starting to arrive in Oregon, so many more could die in the coming weeks in our state, Gillin said.
In other states, bird flu has also been detected in mammals such as skunks, foxes and coyotes, usually in younger animals.
The disease does not pose a high risk to humans, although some have been infected with bird flu viruses. Still, it is a mutant disease, officials said, so hunters should wear protective gear such as masks and gloves to handle wild birds safely, and they should change clothes when they’re going home. Hunters should not kill birds that appear sick. They should also minimize dog interactions with waterfowl.
Some hunters are worried about whether the deaths will impact the duck and goose hunting seasons, which are now open.
“I see quite a few dead geese on Sauvie Island and quite a few sick ones as well,” local hunter Eric Strand said by email.
But Brandon Reishus, Oregon Migratory Bird Coordinator, said it was too early to predict. “We have no intention of closing the hunt. But this is an evolving situation.
The Oregon Department of Agriculture said 16 cases have been confirmed this year in smaller flocks of domestic birds. That’s a significant increase from the two confirmed cases during the 2014-2015 outbreak, said Scholz, the Agriculture Department veterinarian. More herds are being tested after a slight increase in calls over the past week.
About two thousand domestic birds have been euthanized or died from bird flu in Oregon this year in reported cases, Scholz said. Some backyard flock owners only use birds or their eggs for home consumption, while others have hundreds of birds and sell their products to the public. The state imposed several bird flu quarantines this summer and fall to prevent the sale of meat or eggs from areas affected by the virus.
No cases have been reported on commercial farms — farms with much larger herds that are often raised in large barns — likely because they have strict biosecurity measures, Scholz said.
Sick herds ranged from 4 to 500 in size. The larger the flocks, the faster the birds die – so the risk of disease for large farms is great. In the case of a large backyard farm with about 400 chickens, Scholz said, the birds started dying on Saturday and on Monday there were “barrels of dead birds.” Agriculture officials had to euthanize the rest.
And it’s not just a chicken problem. Along with hundreds of dead chickens, this year’s outbreak claimed the lives of domestic ducks, quails, pheasants and even a few emus.
With colder weather and wild bird migration peaking in the coming weeks, the environment is ripe for transmission, Scholz said.
“That kind of weather…that’s a setup for a perfect storm,” he said.
Wildlife officials say it’s okay to double-bagging and throwing one to two dead wild birds in the trash. People can also bury the birds shallow or just leave them where they are found in the wild. Officials said people should be careful about handling the birds and should never transport them.
When it comes to domestic birds, responsible owners can help prevent exposure of their flocks to wild waterfowl by fencing off access to farm ponds or grassy fields, Scholz said.
Owners of domestic flocks should call the Department of Agriculture if more than one bird in their flock dies in quick succession, officials said. Reported cases are examined by a veterinarian and samples are taken for testing. If the disease is confirmed, all birds are euthanized, Scholz said.
“Bird flu is 100% deadly” for domestic birds, which have not developed the immunity some wild birds have, he added. “All the birds will die of the disease. We would rather humanely euthanize them than wait for them to get sick and die.
– Gosia Wozniacki; gwozniacka@oregonian.com; @gosiawozniacka
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