Glaucous-winged Gull

The Glaucous-winged Gull is a large, common gull of the North Pacific coast, breeding from Alaska south through British Columbia and the Pacific Northwest. It closely resembles the more northerly Glaucous Gull but is somewhat smaller and darker gray on the back, with wingtips only faintly darker than the rest of the wing rather than sharply patterned black. It frequently hybridizes with Western Gull where their ranges overlap, producing variably intermediate birds.

Adult mantle feathers are pale to medium gray, and the outer primary flight feathers are only slightly darker gray at the tips rather than sharply black, distinguishing it from most other large gulls including Herring and Western Gull, though the contrast is subtler than in the nearly wingtip-less Glaucous Gull. Immature birds show pale grayish-brown mottled feathers overall, softer and less contrasty than the heavily blotched brown plumage of young Herring Gull, aging over about four years to the adult pattern. Hybrid individuals with Western Gull can show intermediate mantle shades and partial dark wingtip patterning, complicating feather-based identification in areas of overlap such as the Pacific Northwest.

Sexes look alike, with males averaging larger. This is a four-year gull, passing through a series of pale, softly mottled immature plumages before reaching the adult pattern of pale gray mantle with only faintly darker wingtips. Nonbreeding adults show light brownish head streaking, contrasting with the cleaner white head of breeding adults. A complete post-breeding molt replaces flight feathers over an extended period. Hybridization with Western Gull is common and can produce a wide range of intermediate feather patterns.

Breeds along rocky coastlines, offshore islands, and harbors of the North Pacific from Alaska south through British Columbia and into the Pacific Northwest of the United States. It is largely resident to short-distance migratory, remaining along the coast year-round in many areas, foraging in harbors, beaches, tidal flats, and open coastal waters.

Glaucous-winged Gulls are opportunistic feeders, taking fish, marine invertebrates, carrion, and human refuse, and are common around fishing harbors, docks, and coastal towns as well as natural shoreline habitats. Nests are built on the ground on offshore islands, rocky headlands, or occasionally rooftops, often in dense colonies, with both parents sharing incubation and chick-rearing duties. Its call is a deep, resonant series similar to other large gulls. Conservation status is IUCN Least Concern.