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 sou ...

, 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 nom ...

''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 In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...

are often considered separate species.

Taxonomy

The taxonomy is very complex and

species In biology, a species is the basic unit of 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 the appropriat ...

-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 List of South American countries by area, second-largest ...

. ** 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 Dubouze ...

, and locally in southern Argentina and Chile. * Antarctic shag, ''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 1 ...

. * 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. * 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 Islan ...

. * 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 197 ...

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.'' 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 The ''Howard and Moore Complete Checklist of the Birds of the World'' is a book by Richard Howard and Alick Moore which presents a list of the bird species of the world. It was the first single-volume world bird list to include subspecies names, ...

.'' 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).

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 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 nam ...

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,

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., pol ...

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 albatrosses. 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 calle ...

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 " ...

fish,

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

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 made ...

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. The ...

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 depe ...

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. ...

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 The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

. 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