All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing ...

Thayer’s gull (Larus glaucoides thayeri) is a subspecies of the Iceland gull. It is a large gull native to North America that breeds in the Arctic islands of Canada and winters primarily on the ...

A pale northern gull, about the size of Herring Gull but more graceful and maneuverable in flight ... nests in northeastern Canada and winters mostly in eastern Canada and the northeastern United ...

but not like any other regular large gull in the East. Main problem in the west is separation of small female herrings from dark Thayer’s, besides different structure, Thayer’s outer primaries ...