Imagine my suprise yesterday lunchtime...
The tide was rising and leaving me few options on the foreshore for gullage etc. I headed for Wandsworth Park. I thought I might amuse myself by getting some gull ID's wrong. No such time for that as I looked over the fence to the river and saw the top of a Wigeon. Get in! Patch tick! I then took in the rest of the waterfowl on the river and noticed that there were two Wood Ducks there too. Oh, that's really strange thought I. And there was a female too. Okay....
Unfortunately the Wigeon seemed to be quite friendly with the Wood Ducks. So much so that when the Wigeon swam off, the Wood Ducks followed him. And when they all got together again closer to the barges, the Wigeon seemed to be courting the female Wood Duck. Drat.
Getting out Occam's Razor again (sorry) I am left with the following conclusion. 3 non-tickable, probably escaped, ducks are following a duck that is known to be kept in captivity. This duck is cavorting with the female non-tickable duck.
The Wigeon is an escape. Guilty by association. And thenceforthly is not a patch tick.
Four ducks doing plastic.