There's an ugly duckling on my roof

Putting the birds away at dusk I heard this bizarre squawking. It didn't sound like a Barn owl screech to me, but whatever it was caused great disturbance to my duck flocks; they huddled in the corner of their runs, hunkered down as if there was a fox about. I couldn't see or smell anything untoward, but as usual wildlife knows best.
As I came down the farm track towards the house I noticed through the gloom a large bird sitting on the ridge of the roof midway between the chimney pots. It was clearly a duck, but not what I'd call a thing of beauty. The Muscovy or Barbary duck is the turkey of the waterfowl world - basically it has an excess of skin around its face. I cannot love this breed.
I doubt it will go anywhere in the dark, but will probably fly back home once it's light; some folk down the road have Muscovies that perambulate the lanes oblivious to the (admittedly rare) traffic.
You never know what will turn up next. I'm still waiting to come across a zebra, although considering the state of the land, a water buffalo or croc might be more the thing.

Photo by Stuart Brown