Two hawks in Whatcom and Skagit counties are the first confirmed cases of highly pathogenic bird flu in wild raptors in North America.
Highly pathogenic means the strains can be deadly to domestic chickens and turkeys.
The hawks died of other causes — one struck a power line, the other was preyed on by something else — but a necropsy after their deaths showed that the flu was affecting their organs and other tissue, according to Don Kraege, waterfowl section manager for the Washington state Department of Fish and Wildlife.
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Still, the findings worry wildlife officials.
“We are concerned about impacts on raptors,” Kraege said. “They typically have smaller population sizes.”
It’s unknown how the hawks got the flu. They usually eat upland birds and small mammals, such as mice, not waterfowl, which are carriers of the virus, according to Kraege.
“We’re not really sure on the pathway, how they got avian influenza,” he said. “I wouldn’t rule it out that they’re eating some waterfowl, but it’s not the primary part of their diet.”
The two raptors were among the hundreds of wild birds that have been sampled to determine how widespread the highly pathogenic bird flu is in the wild. Results are still some weeks out, and will be used to create a plan for follow-up surveillance.
Wild waterfowl carry the flu but don’t show symptoms. So sampling focused primarily on wild ducks, especially the top four killed by hunters: green-winged teals, widgeons, mallards and northern pintails.
Testing was stepped up here after Canadian inspectors first confirmed the highly pathogenic H5N2 strain at two British Columbia poultry farms in the first week of December.
The week after that, fish and wildlife officials tested two birds found dead in Whatcom County. One was a northern pintail duck, which actually died because of aspergillosis, a fungal disease that birds can contract from eating moldy grain in fields and farm yards. But the duck also carried a strain of bird flu similar to the one that caused the outbreak in B.C.
The other was a gyrfalcon used for hunting; it was fed a wild widgeon, a type of duck, by its owner. Testing showed an H5N8 strain of the virus in the gyrfalcon. The bird was one of four captive gyrfalcons fed the widgeon. All died after, but just one was tested.
The gyrfalcon deaths turned wildlife officials’ attention to raptors.
Both the wild pintail and widgeon were traced to the Wiser Lake area.
The initial findings marked the first time wild birds in North America were found to have highly pathogenic bird flu, and raised concerns for domesticated backyard flocks that come into contact with wild birds in Whatcom County and elsewhere in the region.
Then on Jan. 16, a third strain of highly pathogenic bird flu was confirmed in a wild duck in Whatcom County when tests found the H5N1 strain in a green-winged teal killed by a hunter near Sumas.
Bird flu hasn’t been reported in backyard flocks in Whatcom County, although poultry owners are being urged to keep their birds from coming into contact with wild birds.
Officials have said all three strains aren’t dangerous to the general public because none has infected a human being. Still, they advised those who have backyard flocks, for example, to use caution.
Bird flu hasn’t been found in commercial poultry in Washington state or the U.S.
Meanwhile, wildlife officials continue to encourage the public to contact them if they find dead or sick wild birds, especially raptors.
Sick or dead wild birds can be reported by calling 1-800-606-8768.