Slaty-backed gull
The slaty-backed gull ("Larus schistisagus") is a large, white-headed gull that breeds on the north-eastern coast of the Palearctic, but travels widely during nonbreeding seasons. It is similar in appearance to the western gull and the glaucous-winged gull. Another alternate name is Pacific gull, though it also applies to a Southern Hemisphere species, "L. pacificus". Distribution and habitat. Claims have been made as to its (sometimes occasional) presence throughout North America. as well as the eastern coast of temperate Asia (Palearctic). On 3 November 2012, an individual was spotted in Finland. The species  has only been spotted three times before in Europe. Description. It is tied with the yellow-footed gull for fourth-largest gull species, measuring in length, in wingspan, and in weight. Among standard measurements, the wing chord is , the bill is , and the tarsus is . 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 undersides of the wings feature 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 (the spot near the end of the bill that chicks peck to stimulate regurgitative feeding). Immature gulls' plumage is brown, similar to that of the great black-backed gull, but paler, and is practically indistinguishable from the immature herring gull in the field. Etymology. The genus name is from Latin "larus", which appears to have referred to a gull or other  large seabird. The specific "schistisagus" is from New Latin "schistus", "slate", and Latin "sagus", "cloak".