Visiting Muscovy Duck

A (possibly juvenile male) Muscovy Duck appeared on our pond a few days ago. It has been feeding happily with our resident moorhens and pheasants. It is very bold and will come within three or four feet of us when feeding. Should we encourage it or make it unwelcome? Our domestic Indian Runners and (elderly) Buff Orpingtons are currently shut away but should be released onto the pond soon when DEFRA give the all clear. We don't know how they will interact and we don't want our Buffies being attacked. We have no idea where it has come from, there are no local colonies that we know of.