I had a look at the drake Green-winged Teal in Maldon today and noticed that it is the same bird as recently at Alton Water in South Suffolk. Although it has striking pure white vertical white foreflank lines, it has a hint of a white horizontal scapular stripe and golden-buff edgings to the lower part of the green facial stripe. Last autumn, a drake at Caerlaverock WWT shared similar features.
Now is this within the natural variation of carolinensis or is it evidence of intergradation? Keith Viinicombe has kindly trawled the net for me and found similar examples in North America.
Of course, this drake is much more convincing in plumage to last year's undoubted hybrid at Connaught Water, Epping, but is it really pure?
David Acfield's selection of images of today's bird are posted above
David Sibley has written a nice piece on this subject - see http://www.sibleyguides.com/2011/03/distinguishing-green-winged-and-common-teal/
