Thayer's Gull

Thayer's gull breeds in the Arctic islands of Canada and winters on the Pacific coast from southern Alaska to the Gulf of California. While in Puerto Penasco, Mexico, on the northern portion of the Gulf of California, we encountered some second year immature Thayer's gulls. 

Second year wintering immature Thayer's gull.

The adult has a pale gray mantle, blackish wingtips, pink legs and extensive brown streaking on the head and neck. The head, neck breast, belly and underwings are primarily white. In summer, the head and neck turn white and the bill turns yellow with a larger red spot on the lower mandible. Juveniles are variable from light grayish brown to deep smoky brown. the wingtips are darker than the back, and the bill is all black. The juvenile has black legs that fade to pink, During the second winter the body and head are mostly white, the back has some gray, the wings are still mottled with brown, the bill is dark but has developed a pale base and the wingtips and tail are darker. 

Note the pale gray upper back and the brown mottling on the breast and neck. 

This bird has no mottling on the neck or breast and the feet and legs are a little lighter. 

This out-of-focus shot shows the light gray back.

This shows the contrast between the darker tail and the lighter mottling on the wings.

Several years ago I got pictures of these immature Thayer's gulls at Canaveral Seashore in Florida. These appear to be younger juveniles as they have more brown in their wings and on their heads.