Western Gull

The Western Gull is a large, robust gull found almost exclusively along the Pacific coast of North America, rarely venturing far inland. It shows dark slate-gray back feathers, a notably heavy build and thick bill compared to other large gulls, and is a common sight around harbors, rocky shorelines, and offshore breeding colonies from Washington to Baja California.

Adult mantle feathers are dark slate-gray, darker than California Gull or Herring Gull but generally somewhat paler than the blackish tones of Great Black-backed Gull, though the exact shade shows some geographic variation and overlap with Glaucous-winged Gull in areas where the two hybridize. Outer primary feathers are black with white tips and small mirrors. Immature birds show heavily mottled dark brown feathers, among the darkest-toned immature plumage of the common gray-backed gulls, gradually acquiring the dark adult mantle over about four years. The bill and overall body feather structure appear notably robust and thick-based compared to other similarly sized gulls.

Sexes look alike, with males averaging larger and heavier-billed. This is a four-year gull, with immature plumages showing dark, heavily mottled brown feathers that lighten and gray over successive years. Nonbreeding adults show only limited head streaking, keeping a relatively clean white head much of the year. A complete post-breeding molt replaces flight feathers over an extended period. In areas of range overlap, hybridization with Glaucous-winged Gull produces birds with intermediate mantle shades and feather patterns.

Breeds on rocky offshore islands, sea stacks, and coastal cliffs along the Pacific coast from Washington state to Baja California, Mexico. It is highly coastal and rarely found far from saltwater, foraging along rocky shorelines, harbors, kelp beds, and open coastal waters, with most populations largely resident and only limited local movement outside the breeding season.

Western Gulls forage opportunistically, taking fish, marine invertebrates, seabird eggs and chicks, carrion, and human food waste around harbors and coastal towns. Nests are built on the ground on offshore islands or coastal cliffs, often in dense colonies, with both parents sharing incubation and vigorous defense of the nest site against intruders. Its call is a deep, resonant series of notes typical of large gulls. Conservation status is IUCN Least Concern, with a range tightly restricted to the immediate Pacific coastline.