General

Thayer's Gull: Large gull with gray upperparts and white head, tail, and underparts. Bill is yellow with red spot near the end of the lower mandible. Wings are gray with white-spotted, dark gray tips. Legs are dark pink. Sexes are similar. Winter adult has gray-brown streaks on head, neck, and upper breast. Juvenile is gray-brown overall with white-edged feathers on upperparts, darker tail, black bill, and pink legs and feet. 1st summer is much paler and begins showing yellow base on black bill. 2nd winter has gray mantle, white breast, dark tail, and yellow bill with a dark tip. 3rd winter resembles winter adult but retains black spot on tip of yellow bill.

Range and Habitat

Thayer's Gull: Nests on high rocky cliffs in the Arctic islands and north coast of Northwest Territories. In winter, usually found in bays, meadows, and beaches on the Pacific coast, from central British Columbia to the Baja Peninsula, but occasionally wanders east to the Great Lakes.

Breeding and Nesting

Thayer's Gull: Two to three gray, green, or brown eggs are laid in a ground depression lined with mosses, grass, or lichens, and sheltered by rocks or shrubbery. Incubation ranges from 23 to 27 days and is carried out by both parents.

Foraging and Feeding

Thayer's Gull: Diet consists mostly of carrion and fish, but also eats bird eggs; forages by plunge diving or walking along shorelines.

Vocalization

Thayer's Gull: Song is a loud "kuc-kuc-kuc-kuc-kuckle-kuckle" or "hiyak, hiyak, hiyak-hiyak." Also gives mewing and squealing notes.

Similar Species

Thayer's Gull: Herring Gull is larger, has yellow eyes with orange orbital ring, paler gray back, darker-tipped primaries, paler legs and feet, and heavier bill. Iceland Gull has paler gray back, usually yellow eyes, and translucent pale wing tips.