The fast-moving pathogen, which has already invaded Europe, was found in East Coast ducks. The last outbreak that tore through the US killed 50 million birds.
Nothing has been confirmed. The most common hypothesis I’ve seen is cicadas. A related hypothesis is that cicadas can bioaccumulate toxic shit like pesticides in their long dormant period underground. https://www.birdsoutsidemywindow.org/2021/08/01/update-aug-1-mysterious-bird-illness-is-fading-away/
Nothing has been confirmed. The most common hypothesis I’ve seen is cicadas. A related hypothesis is that cicadas can bioaccumulate toxic shit like pesticides in their long dormant period underground. https://www.birdsoutsidemywindow.org/2021/08/01/update-aug-1-mysterious-bird-illness-is-fading-away/