The Slaty-backed Gull , is a large white-headed gull

Gull

Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...

 that breeds on the western coast of Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 but travels widely during nonbreeding seasons. Claims have been made as to its (sometimes occasional) presence throughout North America as well as the eastern coast of Asia. It is similar in appearance to the Western Gull

Western Gull

The Western Gull, Larus occidentalis, is a large white-headed gull that lives on the western coast of North America. It was previously considered conspecific, the same species, with the Yellow-footed Gull of the Gulf of California...

 and the Glaucous-winged Gull

Glaucous-winged Gull

The Glaucous-winged Gull, Larus glaucescens, is a large, white-headed gull residing from the western coast of Alaska to the coast of Washington. It also breeds on the northwest coast of Alaska. During non-breeding seasons they can be found along the coast of California...

. Another alternate name is Pacific Gull, though this also applies to a southern hemisphere species, Larus pacificus

Pacific Gull

The Pacific Gull is a very large gull, native to the coasts of Australia. It is moderately common between Carnarvon in the west, and Sydney in the east, although it has become scarce in some parts of the south-east, as a result of competition from the Kelp Gull, which has "self-introduced" since...

.

The Slaty-backed Gull is a very large gull, measuring 55–68.5 cm (21.7–27 in) in length, 132–160 cm (52–63 in) in wingspan and weighing 1.05–1.7 kg (2.3–3.7 lb). It has a white head, belly, and tail with a dark slaty-gray back and wings with a broad white trailing edge. The wings and back are slightly darker than those of the Western Gull. The underside of the wings features a "string of pearls" pattern along their edges; these can be seen from below when the bird is in flight. Its eyes are yellow. The legs are pink and short when compared with those of similar-looking gulls, and the body appears more stout. The bill is yellow with orange-red subterminal spot. Immature gulls' plumage is brown, similar to the that of the Great Black-backed Gull

Great Black-backed Gull

The Great Black-backed Gull is the largest gull in the world, which breeds on the European and North American coasts and islands of the North Atlantic...

, but paler, and is practically indistinguishable from the immature Herring Gull

Herring Gull

The European Herring Gull is a large gull , and is the most abundant and best known of all gulls along the shores of western Europe. It breeds across Northern Europe, Western Europe, Scandinavia and the Baltic states...

in the field.

Like other gulls, the Slaty-backed Gull is both a forager and a scavenger.