Ivory Gull
Encyclopedia
The Ivory Gull Pagophila eburnea is a small gull
, the only species
in its genus. It breeds in the high arctic
and has a circumpolar
distribution through Greenland
, northernmost North America
, and Eurasia
.
in 1774 as Larus eburneus from a specimen collected on Spitsbergen
. Johann Jakob Kaup
later recognized the unique traits of the Ivory Gull and gave it a monotypic genus, Pagophila, in 1829. Johan Ernst Gunnerus
later gave the species a new specific name, Pagophila alba. Today some authors consider the Ivory Gull not deserving of its monotypic genus, instead to choosing to merge it, along with the other monotypic gulls, back into Larus. However, most authors have not chosen to do so. The Ivory Gull has no subspecies. No fossil members of this genus are known.
This gull is traditionally believed to be most closely related to either the kittiwake
s, Sabine's Gull
, or Ross's Gull
. It differs anatomically from the other genera by having a relatively short tarsometatarsus
, a narrower os pubis, and potentially more flexibility in skull kinetic structure. Structurally, it is most similar to the kittiwakes; however, recent genetic analysis based on mtDNA sequences shows that Sabine's Gull is the Ivory Gull's closest relative, followed by the kittiwakes, with Ross's Gull and Swallow-tailed Gull
sharing a clade
with these species. "Pagophila" is maintained as a unique genus because of the bird’s morphological, behavioral and ecological differences from these species.
, lacking the grey back of other gulls. The thick bill
is blue with a yellow tip, and the legs are black. Its cry
is a harsh eeeer. Young birds have a dusky face and variable amounts of black flecking in the wings and tail. The juveniles take two years to attain full adult plumage. There are no differences in appearance across the species’ geographic range.
Arctic
. Seymour Island
, Nunavut
is home to the largest known breeding colony, while Ellesmere
, Devon
, Cornwallis, and north Baffin Islands are known locations of breeding colonies. It is believed that there are other small breeding colonies of less than six birds that are still undiscovered. There are no records of the Ivory Gull breeding in Alaska
.
During the winter, Ivory Gulls live near polynyas, or a large area of open water surrounded by sea ice. North American birds, along with some from Greenland and Europe, winter along the 2000 km of ice edge stretching between 50° and 64° N from the Labrador Sea
to Davis Strait
that is bordered by Labrador
and southwestern Greenland. Wintering gulls are often seen on the eastern coasts of Newfoundland and Labrador and occasionally appear on the north shore of the Gulf of St. Lawrence and the interior of Labrador. It also winters from October through June in the Bering Sea
and Chukchi Sea
s. It is most widespread throughout the polynyas and pack ice of the Bering Sea. It is also vagrant throughout coastal Canada and the northeastern United States, though records of individuals as far south as California and Georgia have been reported, with most records from late November through early March. Juveniles tend to wander further from the Arctic than adults.
only short distances south in autumn, most of the population wintering in northern latitudes at the edge of the pack ice, although some birds reach more temperate areas.
and crustacean
s, rodents, eggs and small chicks but is also an opportunist scavenger, often found on seal or porpoise
corpses. It has been known to follow polar bears and other predators to feed on the remains of their kills.
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...
, the only species
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
in its genus. It breeds in the high arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
and has a circumpolar
Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2011, it is the parallel of latitude that runs north of the Equator....
distribution through Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
, northernmost North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, and Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
.
Taxonomy
The Ivory Gull was initially described by Constantine Phipps, 2nd Baron MulgraveConstantine Phipps, 2nd Baron Mulgrave
Constantine John Phipps, 2nd Baron Mulgrave, PC was an English explorer and officer in the Royal Navy. He served during the Seven Years War and the American War of Independence, seeing action in a number of battles and engagements...
in 1774 as Larus eburneus from a specimen collected on Spitsbergen
Spitsbergen
Spitsbergen is the largest and only permanently populated island of the Svalbard archipelago in Norway. Constituting the western-most bulk of the archipelago, it borders the Arctic Ocean, the Norwegian Sea and the Greenland Sea...
. Johann Jakob Kaup
Johann Jakob Kaup
Johann Jakob Kaup was a German naturalist.-Biography:He was born at Darmstadt. After studying at Göttingen and Heidelberg he spent two years at Leiden, where his attention was specially devoted to the amphibians and fishes. He then returned to Darmstadt as an assistant in the grand ducal museum,...
later recognized the unique traits of the Ivory Gull and gave it a monotypic genus, Pagophila, in 1829. Johan Ernst Gunnerus
Johan Ernst Gunnerus
Johan Ernst Gunnerus was a Norwegian bishop and botanist. Gunnerus was born at Christiania. He was bishop of the Diocese of Nidaros from 1758 until his death and also a professor of theology at the University of Copenhagen....
later gave the species a new specific name, Pagophila alba. Today some authors consider the Ivory Gull not deserving of its monotypic genus, instead to choosing to merge it, along with the other monotypic gulls, back into Larus. However, most authors have not chosen to do so. The Ivory Gull has no subspecies. No fossil members of this genus are known.
This gull is traditionally believed to be most closely related to either the kittiwake
Kittiwake
The kittiwakes are two closely related seabird species in the gull family Laridae, the Black-legged Kittiwake and the Red-legged Kittiwake . The epithets "Black-legged" and "Red-legged" are used to distinguish the two species in North America, but in Europe, where R...
s, Sabine's Gull
Sabine's Gull
The Sabine's Gull is a small gull. Its generic placement is disputed; some authors treat it as the sole species in the genus Xema as Xema sabini, while others retain it in the genus Larus as Larus sabini. It breeds in the arctic and has a circumpolar distribution through northernmost North America...
, or Ross's Gull
Ross's Gull
The Ross's Gull is a small gull, the only species in its genus, although it has been suggested it should be moved to the genus Hydrocoloeus, which otherwise only includes the Little Gull....
. It differs anatomically from the other genera by having a relatively short tarsometatarsus
Tarsometatarsus
The tarsometatarsus is a bone that is found in the lower leg of certain tetrapods, namely birds.It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsal and metatarsal bones...
, a narrower os pubis, and potentially more flexibility in skull kinetic structure. Structurally, it is most similar to the kittiwakes; however, recent genetic analysis based on mtDNA sequences shows that Sabine's Gull is the Ivory Gull's closest relative, followed by the kittiwakes, with Ross's Gull and Swallow-tailed Gull
Swallow-tailed Gull
The Swallow-tailed Gull is an equatorial seabird in the gull family Laridae. It is the only species in the genus Creagrus, which derives from the Latin Creagra and the Greek kreourgos which means butcher, also from kreas, meat; according to Jobling it would mean "hook for meat" referring to the...
sharing a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
with these species. "Pagophila" is maintained as a unique genus because of the bird’s morphological, behavioral and ecological differences from these species.
Description
This species is easy to identify. At 43 cm (17 in), it has a different, more pigeon-like shape than the Larus gulls, but the adult has completely white plumagePlumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
, lacking the grey back of other gulls. The thick bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
is blue with a yellow tip, and the legs are black. Its cry
Bird song
Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs are distinguished by function from calls.-Definition:The distinction between songs and calls is based upon...
is a harsh eeeer. Young birds have a dusky face and variable amounts of black flecking in the wings and tail. The juveniles take two years to attain full adult plumage. There are no differences in appearance across the species’ geographic range.
Distribution and habitat
In North America, it only breeds in the CanadianCanada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
. Seymour Island
Seymour Island (Nunavut)
Seymour Island is an uninhabited island in the Qikiqtaaluk Region of northern Canada's territory of Nunavut. A member of the Berkeley Islands group, it is located approximately north of northern Bathurst Island. Between Seymour Island and Bathurst Island lies Helena Island. Penny Strait is...
, Nunavut
Nunavut
Nunavut is the largest and newest federal territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999, via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries had been established in 1993...
is home to the largest known breeding colony, while Ellesmere
Ellesmere
-Places:* Ellesmere, Shropshire, a market town in Shropshire, England** Ellesmere Castle** Ellesmere Rural, a civil parish to the west* Ellesmere Park, area of Eccles, Greater Manchester, England* Ellesmere Port, an industrial town in Cheshire, England...
, Devon
Devon
Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...
, Cornwallis, and north Baffin Islands are known locations of breeding colonies. It is believed that there are other small breeding colonies of less than six birds that are still undiscovered. There are no records of the Ivory Gull breeding in 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...
.
During the winter, Ivory Gulls live near polynyas, or a large area of open water surrounded by sea ice. North American birds, along with some from Greenland and Europe, winter along the 2000 km of ice edge stretching between 50° and 64° N from the Labrador Sea
Labrador Sea
The Labrador Sea is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelves to the southwest, northwest, and northeast. It connects to the north with Baffin Bay through the Davis Strait...
to Davis Strait
Davis Strait
Davis Strait is a northern arm of the Labrador Sea. It lies between mid-western Greenland and Nunavut, Canada's Baffin Island. The strait was named for the English explorer John Davis , who explored the area while seeking a Northwest Passage....
that is bordered by Labrador
Labrador
Labrador is the distinct, northerly region of the Canadian province of Newfoundland and Labrador. It comprises the mainland portion of the province, separated from the island of Newfoundland by the Strait of Belle Isle...
and southwestern Greenland. Wintering gulls are often seen on the eastern coasts of Newfoundland and Labrador and occasionally appear on the north shore of the Gulf of St. Lawrence and the interior of Labrador. It also winters from October through June in the Bering Sea
Bering Sea
The Bering Sea is a marginal sea of the Pacific Ocean. It comprises a deep water basin, which then rises through a narrow slope into the shallower water above the continental shelves....
and Chukchi Sea
Chukchi Sea
Chukchi Sea is a marginal sea of the Arctic Ocean. It is bounded on the west by the De Long Strait, off Wrangel Island, and in the east by Point Barrow, Alaska, beyond which lies the Beaufort Sea. The Bering Strait forms its southernmost limit and connects it to the Bering Sea and the Pacific...
s. It is most widespread throughout the polynyas and pack ice of the Bering Sea. It is also vagrant throughout coastal Canada and the northeastern United States, though records of individuals as far south as California and Georgia have been reported, with most records from late November through early March. Juveniles tend to wander further from the Arctic than adults.
Ecology and behavior
It migratesBird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
only short distances south in autumn, most of the population wintering in northern latitudes at the edge of the pack ice, although some birds reach more temperate areas.
Diet
It takes fishFish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, rodents, eggs and small chicks but is also an opportunist scavenger, often found on seal or porpoise
Porpoise
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen...
corpses. It has been known to follow polar bears and other predators to feed on the remains of their kills.
Reproduction
Ivory Gull breeds on Arctic coasts and cliffs, laying one to three olive eggs in a ground nest lined with moss, lichens, or seaweed.External links
- Ivory Gull in California Ivory Gull information and Photos in California
- Rare Ivory Gull in Plymouth, MA. January 24, 2009
- Satellite tracking of Greenland Ivory Gulls
- Irreplaceable Wild - Ivory Gull
- Oiseaux Photos, illustrations, map.
- FGBOW Photos
- Avibase