The PNAS paper is an interesting one.

It seems to indicate that though H5N1 may be asymptomaitcally caried in wild duck populations, that the virus only cquires sufficient pathogenicity after having been in terrestrial poultry for some period.

That would explain some of the virus qualities seen in the current situation.

H5N1 may have started as an aquatic bird virus, but it’s pathogenic contemporary is derived more from domestic chickens than wild ducks, hence the new propensity for it to kill many species of wild waterfowl (including the geese and swans.)

Although Guan Yi doesn’t draw this conclusion, it seems his work could support the hypothesis.