A rare visitor or an escapee?

Two of these ducks recently turned up at the lake I live on in Surrey. I believe that they are Furruginous Ducks and they are definately not normal residents. Both show a white iris in the eye which I believe means that they are both males.

Does anyone know much about these ducks and whether it's more likely that they are escapees and not a true visitor? The lake has had some rare(ish) ducks on the lake over the years but these are usually clipped and are ringed. I can't see any sign of clipping, but the water clarity is poor so I can't check if they are ringed at this time.

Comments appreciated.

And while am posting, here's a picture of a green woodpecked digging up my lawn. The shot was taken through a double glazed patio window so shows some impefections.

Peter