Found what I suspect was the bird reported recently as an American wigeon. Essentially a drake Eurasian wigeon with a broad green stripe across it's head was feeding at the edge of West Mead pool at 14.00 today. As far as I could tell, all plumage characteristics apart from the green on the head were as for Eurasian wigeon. Quite an interesting bird, I think there was an almost identical bird here a few years ago.