Adult Thayer's Gulls at Ashbridge's Bay in Toronto

This adult Thayer's Gull is molting into breeding plumage. It still has winter head streaking. 15 April 2017. We identified it as Thayer's Gull based on a suite of characters: dark eye; good size and large bill compared to many nearby Kumlien's Gulls, mantle shade same as Herring, blackish primaries approaching black of Herring, white tips in primaries not surrounded by black as in Herring.

Spread wing photo taken from screen shot from video, showing acceptable pattern for Thayer's Gull. Ashbridge's Bay in Toronto on 15 April 2017

Same adult Thayer's Gull with head streaking walking to first summer Kumlien's Gull at Ashbridge's Bay on 16 April 2017

A second adult Thayer's Gull in breeding plumage at Ashbridge's Bay on 16 April 2017. This is a large bird, slightly larger than the Kumlien's Gulls, dark eyed, mantle shade same as Herring, with solid dark primaries.

Link to Ron Pittaway's Taxonomic History of Thayer's Gull