The imperial shag or imperial cormorant (''Leucocarbo atriceps'') is a black and white

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the IOC adopted a consensus taxonomy of seven ge ...

native to southern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

, primarily in rocky coastal regions, but locally also at large inland lakes. Some taxonomic authorities, including the

International Ornithologists' Union The International Ornithologists' Union, formerly known as the International Ornithological Committee, is a group of about 200 international ornithologists, and is responsible for the International Ornithological Congress and other international ...

, place it in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

''Leucocarbo'', others in the genus ''Phalacrocorax''. It is also known as the blue-eyed shag, blue-eyed cormorant and by many other names, and is one of a larger group of cormorants called blue-eyed shags. The

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

is very complex, and several former subspecies are often considered separate species.

Taxonomy

The taxonomy is very complex and

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

-limits within this group remain unresolved. Some taxonomic authorities, including the

, split the group into the species listed below. Others consider the all or part of the group conspecific. The following are considered part of this group: * Imperial shag, ''Leucocarbo (atriceps) atriceps'', from coastal southern

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

and

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...

. ** King cormorant/white-bellied shag, ''Leucocarbo (atriceps) albiventer'', from the

Falkland Islands The Falkland Islands (; es, Islas Malvinas, link=no ) is an archipelago in the South Atlantic Ocean on the Patagonian Shelf. The principal islands are about east of South America's southern Patagonian coast and about from Cape Dubou ...

, and locally in southern Argentina and Chile. *

Antarctic shag The Antarctic shag (''Leucocarbo bransfieldensis''), sometimes referred to as the imperial cormorant, king cormorant, imperial shag, blue-eyed shag or Antarctic cormorant, is the only species of the cormorant family found in the Antarctic. It is s ...

, ''Leucocarbo (atriceps) bransfieldensis'', from the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...

and the

South Shetland Islands The South Shetland Islands are a group of Antarctic islands with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the nearest point of the South Orkney Islands. By the Antarctic Treaty of 195 ...

. * South Georgia shag, ''Leucocarbo (atriceps) georgianus'', from the

South Georgia and the South Sandwich Islands ) , anthem = " God Save the King" , song_type = , song = , image_map = South Georgia and the South Sandwich Islands in United Kingdom.svg , map_caption = Location of South Georgia and the South Sandwich Islands in the southern Atlantic Oc ...

, and

South Orkney Islands The South Orkney Islands are a group of islands in the Southern Ocean, about north-east of the tip of the Antarctic PeninsulaHeard Island shag, ''Leucocarbo (atriceps) nivalis'', from

Heard Island The Territory of Heard Island and McDonald Islands (HIMI) is an Australian external territory comprising a volcanic group of mostly barren Antarctic islands, about two-thirds of the way from Madagascar to Antarctica. The group's overall size ...

. * Crozet shag, ''Leucocarbo (atriceps) melanogenis'', from the Crozet and

Prince Edward Islands The Prince Edward Islands are two small uninhabited islands in the sub-Antarctic Indian Ocean that are part of South Africa. The islands are named Marion Island (named after Marc-Joseph Marion du Fresne, 1724–1772) and Prince Edward Isla ...

. * Macquarie shag, ''Leucocarbo (atriceps) purpurascens'', from

Macquarie Island Macquarie Island is an island in the southwestern Pacific Ocean, about halfway between New Zealand and Antarctica. Regionally part of Oceania and politically a part of Tasmania, Australia, since 1900, it became a Tasmanian State Reserve in 19 ...

While some authorities consider all of the above – except ''albiventer'' – as separate species,Orta, J. (1992). Phalacrocoracidae (Cormorants) in: del Hoyo, J., Elliott, A., & Sargatal, J. eds. (1992). ''

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. ...

.'' Vol. 1. Ostrich to Ducks. Lynx Edicions, Barcelona. Clements, J. F. (2007). ''

The Clements Checklist of Birds of the World ''The Clements Checklist of Birds of the World'' is a book by Jim Clements which presents a list of the bird species of the world. The most recent printed version is the sixth edition (2007), but has been updated yearly, the last version in 202 ...

.'' 6th edition. Christopher Helm. others consider all as subspecies of a single species (as done in this article). Alternatively, some recognize two species, the white-cheeked ''L. atriceps'' (with subspecies ''bransfieldensis'', ''nivalis'' and ''georgianus'') and the black-cheeked ''L. albiventer'' (with subspecies ''melanogenis'' and ''purpurascens''), Dickinson, E. C. eds. (2003). '' Howard and Moore Complete Checklist of the Birds of the World.'' 3d edition. Christopher Helm. or it has been suggested that three species should be recognized: ''L. atriceps'' (including ''albiventer''), ''L. georgianus'' (with subspecies ''bransfieldensis'' and ''nivalis''), and ''L. melanogenis'' (with subspecies ''purpurascens'' and possibly ''verrucosus'', though the latter is relatively distinctive, and most consider it a separate species, the

Kerguelen shag The Kerguelen shag (''Leucocarbo verrucosus'') is a species of cormorant endemic to the Kerguelen Islands in the southern Indian Ocean, one of the most isolated places on Earth. Many authorities consider it a subspecies of the imperial shag. Ra ...

Description

The imperial shag has a total length of and weighs , with males usually larger than females. It is endowed with glossy black feathers covering most of its body, with a white belly and neck. It possesses a distinctive ring of blue skin around its eyes, an orange-yellow nasal knob, pinkish legs and feet, and an erectile black crest. During the non-breeding season, adults lack the crest, have a duller facial area, and less/no white to the back/wings. It has a serrated bill used for catching fish. The group varies primarily in the amount of white on the cheeks/ear-coverts,

wing-coverts A covert feather or tectrix on a bird is one of a set of feathers, called coverts (or ''tectrices''), which, as the name implies, cover other feathers. The coverts help to smooth airflow over the wings and tail. Ear coverts The ear coverts are s ...

and back. Most

taxa In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

have white cheeks and ear-coverts, but these are black in ''albiventer'', ''purpurascens'' and ''melanogenis''. Chicks are uniform brownish, and immatures are brownish and white (instead of black and white), have dull facial skin, and lack the orange-yellow nasal knob and blue eye-ring.

Behavior

Breeding

This is a

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 a ...

monogamous Monogamy ( ) is a form of dyadic relationship in which an individual has only one partner during their lifetime. Alternately, only one partner at any one time ( serial monogamy) — as compared to the various forms of non-monogamy (e.g., polyg ...

species. The colonies are usually relatively small, but some consist of hundreds of pairs and are often shared with other seabirds such as rock shags,

southern rockhopper penguin The southern rockhopper penguin group (''Eudyptes chrysocome''), is a species of rockhopper penguin, that is sometimes considered distinct from the northern rockhopper penguin. It occurs in subantarctic waters of the western Pacific and Indian ...

s and

black-browed albatross The black-browed albatross (''Thalassarche melanophris''), also known as the black-browed mollymawk,Robertson, C. J. R. (2003) is a large seabird of the albatross family Diomedeidae; it is the most widespread and common member of its family. ...

es. Up to five eggs (usually two or three) are placed in a nest made of seaweed and grass, and cemented together with mud and excrement. The eggs usually hatch in about five weeks, and are brooded by both parents. Many chicks and eggs are lost to predators such as

skua The skuas are a group of predatory seabirds with seven species forming the genus ''Stercorarius'', the only genus in the family Stercorariidae. The three smaller skuas, the long-tailed skua, the Arctic skua, and the pomarine skua are called j ...

s and sheathbills.

Feeding

The diet of this species consists of small

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

fish,

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

polychaete Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ...

gastropods The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. ...

and

octopuses An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefis ...

. They primarily feed on fish, especially Argentine anchoita,.Punta, G., Yorio P., and Herrera, G. (2003).
Temporal patterns in the diet and food partitioning in imperial cormorants (Phalacrocorax atriceps) and rock shags (P. magellanicus) breeding at Bahía Bustamante, Argentina.
' Wilson Bulletin 115(3): 307-315 Mean diving depth is almost , and they have been filmed diving as deep as to forage on the sea floor. Most feeding takes place in inshore regions, but at least some populations will travel some distance from the shore to fish.

Status

Overall this species is not considered

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...

and is consequently listed as

Least Concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. Th ...

BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...

and IUCN. Most subspecies are relatively common with estimates of over 10,000 pairs of eachDepartment of the Environment, Water, Heritage and the Arts (2009).
Heard Island Cormorant.
'' Heard Island & McDonald Island. Accessed 2009-01-21.

Notes

Imperial shag landing on Island in Beagle Channel

References

{{Taxonbar, from=Q882373 imperial shag Birds of the Falkland Islands Birds of Patagonia Fauna of Temperate South America imperial shag