The glaucous gull (Larus hyperboreus) is a large gull, the second largest gull in the world, which breeds in Arctic regions of the Northern Hemisphere and winters south to shores of the Holarctic. The genus name is from Latin Larus, which appears to have referred to a gull or other large seabird. The specific hyperboreus is Latin for "northern" from the Ancient Greek Huperboreoi people from the far north  "Glaucous" is from Latin glaucus and denotes a bluish-green or grey colour.
This gull is migratory, wintering from in the North Atlantic and North Pacific oceans as far south as the British Isles and northernmost states of the United States, also on the Great Lakes. A few birds sometimes reach the southern USA and northern Mexico.
This is a large and powerful gull, second largest of all gull species and very pale in all plumages, with no black on either of the wings or the tail. Adults are pale grey above, with a thick yellow bill. Immatures are very pale grey with a pink and black bill. This species is considerably larger, bulkier and thicker-billed than the similar Iceland gull, and can sometimes equal the size of the great black-backed gull, the oft-titled largest gull species. In some areas, glaucous gulls are about the same weight as great black-backed gulls or even heavier and their maximum weight is greater. They can weigh anywhere from 960 to 2,700 g (2.12 to 5.95 lb), with the sexes previously reported to average 1.55 kg (3.4 lb) in males and 1.35 kg (3.0 lb) in females. At the colony on Coats Island in Canada, the gulls are nearly 15% heavier than some other known populations, with a mean weight 1.86 kg (4.1 lb) in 5 males and 1.49 kg (3.3 lb) in 7 females. One other study claimed even higher weights for glaucous gulls, as on Wrangel Island 9 males reportedly averaged 2.32 kg (5.1 lb) and 2.1 kg (4.6 lb) in 6 females, which if accurate would make the glaucous gull the heaviest gull and shorebird in the world if not (as far as is known) the largest linearly on average. These gulls range from 55 to 77 cm (22 to 30 in) in length and can span 132 to 170 cm (52 to 67 in), with some specimens possibly atttaining 182 cm (72 in), across the wings. Among standard measurements, the wing chord is 40.8 to 50.1 cm (16.1 to 19.7 in), the bill is 4.9 to 6.9 cm (1.9 to 2.7 in) and the tarsus is 6 to 7.7 cm (2.4 to 3.0 in). They take four years to reach maturity.
The call is a "laughing" cry similar to that of the herring gull but deeper.
There are four subspecies:
- L. h. hyperboreus, Gunnerus, 1767: nominate, found from northern Europe to north-western Siberia
- L. h. pallidissimus, Portenko, 1939: found from north-western Siberia to the Bering Sea
- L. h. barrovianus, Ridgway, 1886: found from Alaska to north-west Canada
- L. h. leuceretes, Schleep, 1819: found from north-central Canada to Greenland and Iceland
This species breeds colonially or singly on coasts and cliffs, making a lined nest on the ground or cliff. Normally 2–4 light brown eggs with dark chocolate splotches are laid.
These are omnivores like most Larus gulls, and they will eat fish, insects, molluscs, starfish, offal, scraps, eggs, small birds, small mammals and carrion as well as seeds, berries and grains.
Egg, Collection Museum Wiesbaden
- BirdLife International (2015). "Larus hyperboreus". IUCN Red List of Threatened Species. IUCN. 2015: e.T22694343A85048979. Retrieved 4 May 2016.
- Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 198, 219. ISBN 978-1-4081-2501-4.
- "Glaucous". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. (Subscription or UK public library membership required.)
- Dunning Jr., John B., ed. (2008). CRC Handbook of Avian Body Masses (2nd ed.). CRC Press. ISBN 978-1-4200-6444-5.
- Dunning Jr., John B., ed. (1992). CRC Handbook of Avian Body Masses. CRC Press. ISBN 978-0-8493-4258-5.
- Olsen, Klaus Malling; Larsson, Hans (2004). Gulls of North America, Europe, and Asia. Princeton University Press. ISBN 978-0691119977.
- Dementiev, G. P. and N. A. Gladkov. (1951). Ptitsi Sovietskogo Soyuza [Birds of the Soviet Union]. Vol. 2. Israel, in 1968.]: Publishing House Sovietskaya Nauka, Moscow, USSR. [English translation by the Israel Program for Scientific Translations, Jerusalem.
- Weiser, Emily and H. Grant Gilchrist. (2012). Glaucous Gull (Larus hyperboreus), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/glagul. DOI: 10.2173/bna.573
- "Glaucous Gull". All About Birds. Cornell Lab of Ornithology. (2011)
- Harrison, Peter (1991). Seabirds: An Identification Guide. Houghton Mifflin Harcourt. ISBN 978-0-395-60291-1.
|Wikimedia Commons has media related to Larus hyperboreus.|
|Wikispecies has information related to Larus hyperboreus|
- Glaucous gull, Alaska Seabird Information Series
- BirdLife species factsheet for Larus hyperboreus
- "Larus hyperboreus". Avibase.
- "Glaucous gull media". Internet Bird Collection.
- Glaucous gull photo gallery at VIREO (Drexel University)
- Interactive range map of Larus hyperboreus at IUCN Red List maps
- Audio recordings of Glaucous gull on Xeno-canto.
- Larus hyperboreus in the Flickr: Field Guide Birds of the World