Guide to Boreal Birds
This bird has variously been considered a species of its own, a subspecies of the Herring Gull, a subspecies of the Iceland Gull, and even a hybrid of the two. At the moment, it is treated as a species. Distinguishing young Thayer's Gulls from young Herrings is very difficult.
24" (61 cm). In all plumages, very similar to the Herring Gull, gray above, white below, but eye of adult dark instead of yellow. Adults have less white on underside of wing tips than do Herring Gulls.
Mewing and squealing notes.
3 bluish or greenish eggs, spotted with brown, in a nest lined with grass, moss, or lichens placed on a high rocky cliff.
Arctic coasts and islands, usually on rocky cliffs.
Breeds in Canadian high Arctic. Winters chiefly on Pacific Coast south to Baja California. Very rare winter visitor to Maritime Canada and northeastern United States.