This adult Thayer's Gull in winter
plumage was on the beach at Oshawa Harbour on 25 January 2016. Its
identification is based on a combination of 5 characters: (1) It has
blackish wingtips approaching the black of Herring Gull, (2) with
large white primary spots that are not enclosed by black as in
Herring Gull, (3) the eye is dark, (4) the legs are a deep pink, (5)
and the mantle shade is similar to Herring Gull. The head streaking
is also typical of Thayer's in winter.