Adult Thayer's Gull at Barrie, Ontario

Ron Pittaway first spotted this adult winter Thayer's Gull at Heritage Park in Barrie on Lake Simcoe on 17 December 2015. Compared to a Herring Gull, it has large white tips to the blackish primaries, underside of the wingtips are white, mantle shade as dark as on Herring, brighter pink legs, greenish bill with yellowish tip, short bill with slight gonydeal angle, light brownish eyes. It is also slightly smaller in size and smaller billed than most Herring Gulls.


Darkish head streaking forms a hood typical of many adult Thayer's in winter. Also note light brown eye and silvery undersides of primaries.


Primary pattern shows black outer webs on P10, 9 and 8, and light grey inner webs on same primaries.


Thayer's showing pale underwing and dark trailing edge while feeding on minnows. 17 December 2015


Many Thayer's have a full dark subterminal band on Primary 5, but on others it is incomplete such as on this individual (dark spot) and frequently a dark bar is lacking on P5 (Snell 2002 in BNA, and Olsen and Larsson 2004). Photo by Brennan Obermayer.


Same adult Thayer's Gull on 18 December 2015.


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