It is all pointless. The wild bird population isn't likely to die out or stop flying around pooping and it's unlikely that we will keep hens in until they do either.
My hens are in, but I strongly suspect I'm the only person in the area who is keeping them in.
The local wildlife sanctuary who also has poultry, pigeons and waterfowl as well as vast numbers of seagulls who come and go, haven't got theirs shut in - they are only feeding under cover and not taking in any ill birds.