A puzzle.

I don’t believe there was already H5N1 in all the places dead swans with H5N1 found (seems there have been movements spurred by freezing weather).

Yet, puzzling re just how and where they are being/have been infected.
(Earlier, had swans arrive Hungary in autumn, evidently healthy; move to Romania, and infected and dying – but H5N1 not found on ponds where they were dying.)

Are swans in east Asia, too; not many mute swans tho (the species impacted w Asia/Europe I believe). Not south to HK, but are in Japan westwards.
Yet, no problems evident w swans here, not even back to 2003/04.
Get various birds die from H5N1 – herons, egrets, gulls etc etc (even if you consider ducks somehow immune [by no means certain], or so few die that won’t be evident).
Why, then, (mute) swans in Europe/w Asia?