Thai National Parks

Birds of Thailand

Species of Thailand

Slaty-backed gull

In Thai: นกนางนวลหลังเทา, nok naang nuan lang thao

Binomial name: Larus schistisagus, Leonhard Hess Stejneger, 1884

The slaty-backed gull (Larus schistisagus) is a large white-headed gull that breeds on the western coast of Alaska 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 this also applies to a southern hemisphere species, Larus pacificus. Claims have been made as to its (sometimes occasional) presence throughout North America as well as the eastern coast of Asia. On November 3, 2012, an individual was spotted in Finland. The species has only been spotted three times before in Europe.

The slaty-backed gull is the fourth largest species of gull in the world. It is considered the North Pacific equivalent of the largest gull species, the great black-backed gull. measuring 55 - 68.5 cm in length, 132 - 160 cm in wingspan and weighing 1.05 - 1.7 kg. Among standard measurements, the wing chord is 40.6 to 48 cm, the bill is 4.8 to 6.5 cm and the tarsus is 6 to 7.6 cm. 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, but paler, and is practically indistinguishable from the immature herring gull in the field.

Like other gulls, the slaty-backed gull is both a forager and a scavenger.

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Scientific classification

Larus schistisagus

Common names

  • Thai: นกนางนวลหลังเทา, nok naang nuan lang thao

Conservation status

Least Concern (IUCN3.1)

Least Concern (IUCN3.1)

Range Map

Distribution map of Slaty-backed gull, Larus schistisagus in Thailand
  • Bang Pu Recreation Centre
  • Laem Pak Bia
Range map of Larus schistisagus in Thailand