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Thayer's gull (''Larus glaucoides thayeri'') is a
subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
of the Iceland gull. It is a large
gull Gulls, or colloquially seagulls, are seabirds of the subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...
native to
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
.


Distribution

This gull breeds in the Arctic islands of
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
and winters primarily on the
Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...
coast, from southern
Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
to the
Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...
, though there are also wintering populations on the
Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...
and the upper
Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...
. The species has occurred as a vagrant to
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
,
Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
, and other parts of western Europe. Somewhat intermediate between
American herring gull The American herring gull or Smithsonian gull (''Larus smithsonianus'' or ''Larus argentatus smithsonianus'') is a large gull that breeds in North America, where it is treated by the American Ornithological Society as a subspecies of herring gu ...
and Iceland gull in habit and appearance and at times considered conspecific with either species, the adult Thayer's gull in nonbreeding plumage has a pale gray mantle, with obvious blackish wingtips, and extensive brown streaking on the head and neck. The head, neck, breast, belly, and underwings are primarily white, and the legs are pink. There is a red spot on the lower mandible, and the color of the iris is generally dark. In summer, the head and neck are white, with the bill turning bright yellow with a larger red spot on the lower mandible. Juvenile gulls are brown, with black bills, and black legs which quickly fade to adult pink. Thayer's Gull reaches a length of , with a wingspan of and a weight of approximately .''Gulls: Of North America, Europe, and Asia'' by Klaus Malling Olsen & Hans Larsson. Princeton University Press (2004). .Harrison, Peter, ''Seabirds: An Identification Guide''. Houghton Mifflin Harcourt (1991), Males average around and females, being slightly smaller, average .''CRC Handbook of Avian Body Masses'' by John B. Dunning Jr. (Editor). CRC Press (1992), . Among standard measurements, the wing chord is , the bill is and the tarsus is . During winter, it is found in small numbers among mixed flocks of large gulls, though it may gather in large numbers in certain locations. In summer, it is found on the tundra of high Arctic islands. These gulls will lay 3 bluish or greenish eggs in nests lined with grass, moss or lichens. Their voice consists of mostly mewing and squealing notes. There is continuing debate about the taxonomic status of this species, and some authorities consider Thayer's gull to be the dark-mantled form of Iceland gull, with Kumlien's gull (variously treated as a subspecies of either Thayer's or Iceland gulls) as an intermediate example, forming a
cline Cline may refer to: Science * Cline (biology), a measurable gradient in a single trait in a species across its geographical range * Cline (hydrology), a fluid layer with a property that varies * Cline (mathematics) or generalised circle, a ci ...
rather than separate species. The
American Ornithologists' Union The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its ...
considered Thayer's gull a subspecies of American herring gull from 1917 until 1973, when they determined it was a separate species from herring gull. After numerous papers had been written suggesting downgrading this species to a subspecies or even a morph of Iceland gull, the
American Ornithologists' Union The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its ...
invalidated Thayer's gull as a full species in the 2017 annual supplement to the
American Ornithologists' Union The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its ...
checklist. Thayer's gull is now considered a subspecies of Iceland Gull. The
British Ornithologists' Union The British Ornithologists' Union (BOU) aims to encourage the study of birds (ornithology) around the world in order to understand their biology and aid their conservation. The BOU was founded in 1858 by Professor Alfred Newton, Henry Baker ...
classified this species as a subspecies of Iceland gull in 1991. Along with the AOS, the BOU lumps the three (''thayeri, kumlieni'', and ''glaucoides'') as forms of Iceland gull. Both the common and species names honor ornithologist John Eliot Thayer, and so the first part of its name is pronounced "THAY-erz".


References

*del Hoyo, J., et al., eds. (1996). ''
Handbook of the Birds of the World The ''Handbook of the Birds of the World'' (HBW) is a multi-volume series produced by the Spanish publishing house Lynx Edicions in partnership with BirdLife International. It is the first handbook to cover every known living species of bird. ...
'' 3: 609. Lynx Edicions. * *Sibley, David Allen. (2003). ''The Sibley Field Guide to Birds of Western North America'' *


External links


Thayer's Gull
at Avibase

taxonomic history, at ''Ontario Birds''

at USGS
Flicker Field Guide Birds of the World
Photographs {{Taxonbar, from=Q632588 Thayer's gull Birds of the Arctic Birds of Canada Thayer's gull