Imperial shag | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Suliformes |
Family: | Phalacrocoracidae |
Genus: | Leucocarbo |
Species: | L. atriceps |
Binomial name | |
Leucocarbo atriceps (King, PP, 1828) | |
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Synonyms | |
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The imperial shag or imperial cormorant (Leucocarbo atriceps) is a black and white cormorant native to southern South America, primarily in rocky coastal regions, but locally also at large inland lakes. Some taxonomic authorities, including the International Ornithologists' Union, place it in the genus 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. [2] The taxonomy is very complex, and several former subspecies are often considered separate species.
The taxonomy is very complex and species-limits within this group remain unresolved. Some taxonomic authorities, including the International Ornithologists' Union, split the group into the species listed below. Others consider all or part of the group conspecific. The following are considered part of this group:
While some authorities consider all of the above – except albiventer – as separate species, [7] [8] others consider all as subspecies of a single species [9] (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), [10] 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). [3]
The imperial shag has a total length of 70–79 cm (28–31 in) and weighs 1.8–3.5 kg (4.0–7.7 lb), with males usually larger than females. [3] 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. [7] During the non-breeding season, adults lack the crest, have a duller facial area, and less/no white to the back/wings. [3] 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 have white cheeks and ear-coverts, but these are black in albiventer, purpurascens and melanogenis. [3] 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. [3]
This is a colonial, monogamous 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 penguins and black-browed albatrosses. [3] [7] 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. [7] The eggs usually hatch in about five weeks, and are brooded by both parents. [11] Many chicks and eggs are lost to predators such as skuas and sheathbills. [11]
The diet of this species consists of small benthic fish, crustaceans, polychaetes, gastropods and octopuses. [7] They primarily feed on fish, especially Argentine anchoita,. [12] Mean diving depth is almost 25 m (82 ft), and they have been filmed diving as deep as 60 m (200 ft) to forage on the sea floor. [12] [13] Most feeding takes place in inshore regions, but at least some populations will travel some distance from the shore to fish. [3]
Overall this species is not considered threatened and is consequently listed as Least Concern by BirdLife International and IUCN. [1] Most subspecies are relatively common with estimates of over 10,000 pairs of each [14]
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) adopted a consensus taxonomy of seven genera. The great cormorant and the common shag are the only two species of the family commonly encountered in Britain and Ireland and "cormorant" and "shag" appellations have been later assigned to different species in the family somewhat haphazardly.
The pelagic cormorant, also known as Baird's cormorant or violet-green cormorant, is a small member of the cormorant family Phalacrocoracidae. Analogous to other smallish cormorants, it is also called the pelagic shag occasionally. This seabird lives along the coasts of the northern Pacific; during winter it can also be found in the open ocean. Pelagic cormorants have relatively short wings due to their need for economical movement underwater, and consequently have the highest flight costs of any bird.
The little pied cormorant, little shag or kawaupaka is a common Australasian waterbird, found around the coasts, islands, estuaries, and inland waters of Australia, New Guinea, New Zealand, Timor-Leste, and Indonesia, and around the islands of the south-western Pacific and the subantarctic. It is a small short-billed cormorant usually black above and white below with a yellow bill and small crest, although a mostly black white-throated form predominates in New Zealand. Three subspecies are recognised. Until recently most authorities referred to this species as Phalacrocorax melanoleucos.
The European shag or common shag is a species of cormorant. It is the only member of the monotypic genus Gulosus. It breeds around the rocky coasts of western and southern Europe, southwest Asia and north Africa, mainly wintering in its breeding range except for the northernmost birds. In Britain this seabird is usually referred to as simply the shag. The scientific genus name derives from the Latin for glutton. The species name aristotelis commemorates the Greek philosopher Aristotle.
The guanay cormorant or guanay shag is a member of the cormorant family found on the Pacific coast of Peru and northern Chile. After breeding it spreads south to southern parts of Chile and north to Ecuador, and has also been recorded as far north as Panama and Colombia – probably a result of mass dispersal due to food shortage in El Niño years. Its major habitats include shallow seawater and rocky shores.
The rock shag, also known as the Magellanic cormorant, is a marine cormorant found around the southernmost coasts of South America. Its breeding range is from around Valdivia, Chile, south to Cape Horn and Tierra del Fuego, and north to Punta Tombo in Argentina. In winter it is seen further north, with individuals reaching as far as Santiago, Chile on the west coast and Uruguay on the east. The birds also breed around the coasts of the Falkland Islands.
The New Zealand king shag, also known as the rough-faced shag, king shag or kawau tūī, is a rare bird endemic to New Zealand. Some taxonomic authorities, including the International Ornithologists' Union, place this species in the genus Leucocarbo. Others place it in the genus Phalacrocorax.
The black-faced cormorant, also known as the black-faced shag, is a medium-sized member of the cormorant family. Upperparts, including facial skin and bill, are black, with white underparts. It is endemic to coastal regions of southern Australia.
The Auckland shag or Auckland Islands shag is a species of cormorant from New Zealand. The species is endemic to the Auckland Islands archipelago. It is a sedentary bird that primarily eats various crustaceans and fish. In recent years, roughly 1,000 pairs have been recorded. The Auckland shag is a colonial nester, building sizeable nests of, among other items, grass, twigs and seaweed. The Auckland shag lays three pale blue-green eggs in November–February. The incubation period is 26–32 days.
The Chatham shag, also known as the Chatham Island shag, is a species of bird in the cormorant and shag family, Phalacrocoracidae. It is endemic to the Chatham Islands of New Zealand. For a long time the species was placed in the genus Phalacrocorax; today it is mostly placed with the other blue-eyed shags of New Zealand and Antarctica in the genus Leucocarbo. Its closest relative is the Otago shag of South Island.
The Bounty shag, also known as the Bounty Island shag, is a species of cormorant of the family Phalacrocoracidae. They are found only on the tiny and remote Subantarctic Bounty Islands, 670 km (420 mi) southeast of New Zealand. Its natural habitats are open seas and rocky shores. In 2022, a full Unmanned aerial vehicle survey of the Bounty archipelago found a total of 573 breeding pairs and estimates the population to consist of approximately 1,733 birds. These recent estimates are consistent with the only other comparable study from 1978 and suggest that the species' population has remained stable over the past 45 years.
The Kerguelen shag 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.
The South Georgia shag, also known as the South Georgia cormorant, is a marine cormorant native to South Georgia and a few other subantarctic islands in the South Atlantic Ocean.
The Heard Island shag, or Heard Island cormorant, is a marine cormorant native to the Australian territory comprising the Heard and McDonald Islands in the Southern Ocean, about 4100 km south-west of Perth, Western Australia.
The Macquarie shag, Macquarie Island shag or Macquarie Island cormorant, is a marine cormorant native to Macquarie Island in the Southern Ocean, about halfway between Australia and Antarctica.
The order Suliformes is an order recognised by the International Ornithologist's Union. In regard to the recent evidence that the traditional Pelecaniformes is polyphyletic, it has been suggested that the group be divided to reflect the true evolutionary relationships, a 2017 study indicated that they are most closely related to Otidiformes (bustards) and Ciconiiformes (storks).
The Crozet shag, also known as the South Georgia cormorant, is a marine cormorant native to the Crozet, Prince Edward and Marion islands in the South Atlantic Ocean.
The Antarctic shag, 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 sometimes considered conspecific with the Imperial shag.