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 International Ornithologists' Union (IOU) ado ...

native to southern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

, islands of the

Subantarctic The sub-Antarctic zone is a physiographic region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46th parallel south, 46° and 60th parallel south, 60° south of t ...

, and the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin 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 Antarctica. ...

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

International Ornithologists' Union The International Ornithologists' Union (IOU) is an international organization for the promotion of ornithology Ornithology, from Ancient Greek ὄρνις (''órnis''), meaning "bird", and -logy from λόγος (''lógos''), meaning "study", ...

, place it in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''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 image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

is complex, and several types are treated as either

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 ...

or separate species.

Taxonomy

The taxonomy is complex, and

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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

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

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

and

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

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

Falkland Islands The Falkland Islands (; ), commonly referred to as The Falklands, 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 from Cape Dub ...

, and locally in southern Argentina and Chile. * Antarctic shag, ''Leucocarbo (atriceps) bransfieldensis'', from the

and the

South Shetland Islands The South Shetland Islands are a group of List of Antarctic and subantarctic islands, Antarctic islands located in the Drake Passage with a total area of . They lie about north of the Antarctic Peninsula, and between southwest of the n ...

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

South Georgia and the South Sandwich Islands South Georgia and the South Sandwich Islands (SGSSI) is a British Overseas Territory in the southern Atlantic Ocean. It is a remote and inhospitable collection of islands, consisting of South Georgia and a chain of smaller islands known as the ...

, and

South Orkney Islands The South Orkney Islands are a group of List of Antarctic and sub-Antarctic islands, 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 land ...

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

Prince Edward Islands The Prince Edward Islands are two small uninhabited subantarctic volcanic islands in the southern Indian Ocean that are administered by South Africa. They are named Marion Island (named after Marc-Joseph Marion du Fresne, 1724–1772) and P ...

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

Macquarie Island Macquarie Island is a subantarctic island in the south-western Pacific Ocean, about halfway between New Zealand and Antarctica. It has been governed as a part of Tasmania, Australia, since 1880. It became a Protected areas of Tasmania, Tasmania ...

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 more 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 or no white to the back and 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''; : 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 name and ...

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 relationship of two individuals in which they form a mutual and exclusive intimate partnership. Having only one partner at any one time, whether for life or serial monogamy, contrasts with various forms of non-monogamy (e.g. ...

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 western rockhopper penguin (''Eudyptes chrysocome''), traditionally known as the southern rockhopper penguin, is a species of rockhopper penguin that is sometimes considered distinct from the northern rockhopper penguin. It occurs in subanta ...

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 skuas 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 the Ancient Greek word (), meaning "the depths". ...

fish,

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

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

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

and

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

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

and is consequently listed as

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

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 i ...

and

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

. Most subspecies are relatively common, with estimates of over 10,000 pairs of each.Department 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 The imperial shag or imperial cormorant (''Leucocarbo atriceps'') is a black-and-white cormorant native to southern South America, islands of the Subantarctic, and the Antarctic Peninsula, primarily in rocky coastal regions, but locally also at ...

Birds of the Falkland Islands Birds of Patagonia Fauna of Temperate South America