European GoldFinch

This is the first Goldfinch I have seen at the feeding station this year.I have heard them and seen them from a distance .
  It's nice to have them back 
I have heard that they have been affected by a virus,which is spread @ the feeders because of bad hygiene?
   Hopefully the situation will improve?
Three winters ago I was getting flocks of 20-30 @ a time!