Good for you, Ash, for doing the legwork on this. I found a female Hooded Merganser in Tenerife some years ago, which I believe became perhaps the first proven genuine Transatlantic migrant. It was exhausted and suspicious when it arrived, and crucially, we did some research on the island about wildfowl collections, as part of the provenance. They do come over, and eliminating the possible is a necessary first step in raising their possible wild origin. Well done, and a pity!
He has none of the scaup species in his collection - the nearest species is a few tufties.
He hasn't had a RN Duck in the past 8 or so years - so I suspect his escapees are unlikely to still be around (don't know the average age for RN Duck survival in the wild) - but this is getting into the realms of speculation, so I'll bow out now.
