Thayerís Gull (Larus thayeri)

While this bird is now a species of its own, it was once known as a subspecies of the herring gull and the Iceland gull. It was once even considered as a hybrid of the two!

Description

Thayerís gulls are large birds, averaging 60 cm in length and weighing between 900-1100 g. Males and females are similar in appearance, and both require four years to reach full adult plumage, when they sport a grey mantle and wings, with dark grey wing-tips and white primary tips. The head and breast have heavy, pale brown mottling, while the flanks, belly, and tail are white. The mature gullís bill is yellow with a red spot near the end of the lower bill, and its legs are dark pink. In contrast, juvenile gulls have a brown mantle and wings, a black bill, and pale pink legs.

Distribution

Thayer's gull breeds on the High Arctic islands and on the north coast of the Northwest Territories. In winter, it is normally found on the west coast, from central British Columbia to the Baja Peninsula, but occasionally wanders eastward to the Great Lakes. During the winter these birds are often seen in bays, meadows and beaches on the Pacific coast.

Ecology

Thayer's gull builds its nest on high rocky cliffs in the Arctic islands, and lines them with mosses, grass, or lichens. It lays 2-3 bluish, brown eggs hat are incubated by the female for up to 28 days.

It's diet consists mostly of carrion and fish and to some extent eggs.