combination may be found along the Pacific coast from Alaska down to southern California, and are highly variable, sometimes resembling Thayer's gull but with a larger bill and inconsistent wing pattern. They typically have paler eyes and darker primaries than Glaucous-winged, and the winter head pattern of either parent species (Herring gull has a more streaked winter hood). Hybrids with Glaucous gull are common in west Alaska where up to 50% of birds in the Seward Peninsula are hybrids, and rare visitors further south to Japan and California. Hybrids with Slaty-backed gull are uncommon but have been known to breed on the east coast of the Kamchatka Peninsula and Commander Islands, reaching south to Japan in winter. References Further reading Identification King, Jon (2007) Identification of Glaucous-winged Gull: a photo-gallery Birding World 20(2):64-72 External links Detailed year-to-year plumage of the glaucous-winged gull Glaucous-winged gull at Animal Diversity Web glaucous-winged gull Native birds of Alaska Native birds of Western Canada Birds of North Asia glaucous-winged gull glaucous-winged gull