The rock shag (''Leucocarbo magellanicus''), also known as the Magellanic cormorant, is a marine

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 ...

found around the southernmost coasts of

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 southe ...

. Its breeding range is from around

Valdivia Valdivia (; Mapuche: Ainil) is a city and commune in southern Chile, administered by the Municipality of Valdivia. The city is named after its founder Pedro de Valdivia and is located at the confluence of the Calle-Calle, Valdivia, and Cau-Cau R ...

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 east a ...

, south to

Cape Horn Cape Horn ( es, Cabo de Hornos, ) is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island. Although not the most southerly point of South America (which are the Diego Ramírez ...

and

Tierra del Fuego Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla G ...

, and north to

Punta Tombo Punta Tombo is a peninsula into the Atlantic Ocean south of Trelew in Chubut Province, Argentina, where there is a large colony of Magellanic penguins - the largest such colony in Argentina. It is a short distance north of Camarones. Natura ...

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, th ...

. In winter it is seen further north, with individuals reaching as far as

Santiago, Chile Santiago (, ; ), also known as Santiago de Chile, is the capital (political), capital and largest city of Chile as well as one of the largest cities in the Americas. It is the center of Chile's most densely populated Regions of Chile, region, t ...

on the west coast and

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

on the east. The birds also breed around the coasts of 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 Dubouzet ...

Taxonomy

The rock shag was formally described in 1789 by the German naturalist

Johann Friedrich Gmelin , fields = , workplaces = University of GöttingenUniversity of Tübingen , alma_mater = University of Tübingen , doctoral_advisor = Philipp Friedrich GmelinFerdinand Christoph Oetinger , academic_advisors = , doctora ...

in his revised and expanded edition of

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...

's ''

Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...

''. He placed it in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

'' Pelecanus'' and coined the

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''Pelecanus magellanicus''. Gmelin based his description on the "Magellanic shag" that had been described in 1785 by the English ornithologist John Latham in his book ''A General Synopsis of Birds''. Latham had in turn based his description on a specimen in the

Leverian Museum The Leverian collection was a natural history and ethnographic collection assembled by Ashton Lever. It was noted for the content it acquired from the voyages of Captain James Cook. For three decades it was displayed in London, being broken up ...

and the account made by

Georg Forster Johann George Adam Forster, also known as Georg Forster (, 27 November 1754 – 10 January 1794), was a German naturalist, ethnologist, travel writer, journalist and revolutionary. At an early age, he accompanied his father, Johann Reinhold F ...

of his visit to

in December 1774 during

James Cook James Cook (7 November 1728 Old Style date: 27 October – 14 February 1779) was a British explorer, navigator, cartographer, and captain in the British Royal Navy, famous for his three voyages between 1768 and 1779 in the Pacific Ocean an ...

's second voyage to the Pacific. The rock shag was formerly placed in the genus ''

Phalacrocorax ''Phalacrocorax'' is a genus of fish-eating birds in the cormorant family Phalacrocoracidae. Members of this genus are also known as the Old World cormorants. Taxonomy The genus ''Phalacrocorax'' was introduced by the French zoologist Mathurin ...

'' but based on the results of a

molecular genetic Molecular genetics is a sub-field of biology that addresses how differences in the structures or expression of DNA molecules manifests as variation among organisms. Molecular genetics often applies an "investigative approach" to determine the ...

study of the cormorants published in 2014, the species was moved to the genus ''

Leucocarbo ''Leucocarbo'' is a genus of birds in the family Phalacrocoracidae with the members commonly known as blue-eyed shags. This is a group of closely related cormorant taxa. Many have a blue, purple or red ring around the eye (not a blue iris); other ...

''. The genus had been introduced in 1856 by the French naturalist

Charles Lucien Bonaparte Charles Lucien Jules Laurent Bonaparte, 2nd Prince of Canino and Musignano (24 May 1803 – 29 July 1857), was a French naturalist and ornithologist. Lucien and his wife had twelve children, including Cardinal Lucien Bonaparte. Life and career ...

. The genus name combines the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''leukos'' meaning "white" with the name ''Carbo'' introduced by

Bernard Germain de Lacépède Bernard-Germain-Étienne de La Ville-sur-Illon, comte de Lacépède or La Cépède (; 26 December 17566 October 1825) was a French naturalist and an active freemason. He is known for his contribution to the Comte de Buffon's great work, the ...

in 1799. The species is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

: no

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 species ...

are recognised.

Description

At a distance, the rock shag is a black and white bird, with head, neck and upperparts black and chest and underparts white. Closer up, the black areas vary from metallic blue to oily green, and are flecked with white in places. The legs and feet are a pink, fleshy colour, and the bare flesh around the beak and eyes is brick red. In breeding condition, there is a blackish though not very prominent crest on the forehead, and a distinctive white ear patch. There is even less

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

than in most cormorant species, but males are 5%-10% larger on most size measurements.

Behaviour and ecology

Food and feeding

Like all cormorants, the rock shag feeds by diving for underwater prey. It feeds close to shore, often diving at the edge of

kelp Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera. Despite its appearance, kelp is not a plant - it is a heterokont, a completely unrelated group of organisms. Kelp grows in "underwat ...

beds and apparently finding small fish (predominantly cod icefishes, ''

Patagonotothen ''Patagonotothen'' is a genus of marine ray-finned fishes, belonging to the family Nototheniidae, the notothens or cod icefishes. They are native to the southeast Pacific Ocean, southern Atlantic Ocean and the Southern Ocean. Taxonomy ''Patagono ...

'' species) sheltering among the weed. Studies with

depth gauge A depth gauge is an instrument for measuring depth below a reference surface. They include depth gauges for underwater diving and similar applications, and engineering instruments used to measure the depth of holes and indentations from a refer ...

s suggest that it is a fairly shallow diver, typically going about 5 m below the surface with few individuals diving deeper than 10 m, although its prey mainly comes from the sea floor. Dive times are typically around 30 seconds. Its breeding range overlaps markedly with that of the

imperial shag 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 ...

''Leucocarbo atriceps'', but the two species' foraging ranges are different since the imperial shag tends to dive in deeper water, further out from shore.

Breeding

The rock shag usually nests on ledges on steep, bare, rocky cliffs. It normally lays three eggs, though nests of from two to five eggs have been seen. Nesting colonies range is size from five pairs to nearly 400.

References

*Johnsgaard, P. A. (1993). ''Cormorants, darters and pelicans of the world''. Washington DC, Smithsonian Institution Press. *Punta, G., Yorio, P., & Herrera, G. (2003). Temporal patterns in the diet and food partitioning in imperial cormorants (''Phalacrocorax atriceps'') and rock shags (''P. magellanicus'') breeding at Bahia Bustamante, Argentina. ''Wilson Bulletin, 115'', 307–315. *Sapoznikow, A., & Quintana, F. (2006). Colony attendance pattern of Rock Shags (Phalacrocorax magellanicus): an evidence of the use of predictable and low seasonally food sources? ''Ornitologia Neotropical, 17'', 95-103. *Wanless, S., & Harris, M. P. (1991). Diving patterns of full-grown and juvenile rock shags. ''Condor, 93'', 44–48. {{Taxonbar, from=Q202518

rock shag The rock shag (''Leucocarbo magellanicus''), 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 de ...

Birds of Patagonia Birds of Tierra del Fuego Birds of the Falkland Islands Southeastern South American coastal fauna