Thanks for the information. It’s more of what I was looking for. I did find another source on the internet that showed the “flyways” as sort of amorphous blobs that flow generally north and south like you describe.
It’s easy to see how H5N1 can move from flyway to flyway as they do tend to overlap very heavily. All it takes to pollute a new area with a suspect infectious agent is time and proximity.
If, as might be the case, this is what is happening, the mechanism looks like it’s there. But where’s the PROOF!!!