A new Caspian-type. Yellow ringed bird X683. Could be a hybrid Caspian Gull as there is extensive dark in lesser and median covert and structurally the bird wasn't quite compact.
The usual first-winter Caspian Gull
The hybrid Ferruginous-like Duck (above and below). Probably wouldn't dismiss this bird as a hybrid if I saw it like this within it's usual range