In the past three years, scientists have documented a slow but steady increase in the number of Pacific Northwest species that are dying from avian influenza, commonly known as bird flu.

Wild birds have long carried low pathogenic strains of avian influenza. When it spread to domestic birds, the virus sometimes mutated into more severe strains, called high pathogenic avian influenza—or HPAI.

For decades, HPAI was a disease that largely affected domestic poultry, and sometimes the people who handle them. But in a paradigm shift, the strain started spreading back to wild bird populations in 2002.

Now, the latest strain of HPAI H5N1—emerging in 2021—is proving to be especially worrisome to wild birds, and potentially to other wildlife.

In 2022, some migratory birds that spend time in Wash

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