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 International Ornithologists' Union (IOU) ado ...

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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. 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 ...

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 ...

, south to

Cape Horn Cape Horn (, ) 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 is Águila Islet), Cape Horn marks the nor ...

and

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

, and north to Punta Tombo in

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 ...

. 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 and largest city of Chile and one of the largest cities in the Americas. It is located in the country's central valley and is the center of the Santiago Metropolitan Regi ...

on the west coast and

Uruguay Uruguay, officially the Oriental Republic of 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 the Río de la Plata to the south and the A ...

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

Taxonomy

The rock shag was

formally described A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differ ...

in 1789 by the German naturalist

Johann Friedrich Gmelin Johann Friedrich Gmelin (8 August 1748 – 1 November 1804) was a German natural history, naturalist, chemist, botanist, entomologist, herpetologist, and malacologist. Education Johann Friedrich Gmelin was born as the eldest son of Philipp F ...

in his revised and expanded edition of

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

's ''

Systema Naturae ' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...

''. He placed 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 ...

'' Pelecanus'' and coined the

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

''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 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 geography, geographer, natural history, naturalist, ethnology, ethnologist, travel literature, travel writer, journalist and revol ...

of his visit to

in December 1774 during

James Cook Captain (Royal Navy), Captain James Cook (7 November 1728 – 14 February 1779) was a British Royal Navy officer, explorer, and cartographer famous for his three voyages of exploration to the Pacific and Southern Oceans, conducted between 176 ...

'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 branch 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 str ...

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. Several species within the genus are collectively known as blue-eyed shags. This is a group of closely related cormorant taxa. Many have a blue, purple or red ring around the ey ...

''. 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 ornithology, ornithologist, and a nephew of Napoleon. Lucien and his wife had twelve children, including Cardinal ...

. The genus name combines the

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

''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 natural history, naturalist and an active freemason. He is known for his contribution to the Comte de Buffon's g ...

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 "unisp ...

: no

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 ...

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 sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

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 or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...

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 ''Patagon ...

'' species) sheltering among the weed. Studies with

depth gauge A depth gauge is an instrument for measuring depth (coordinate), depth below a vertical reference surface. They include depth gauges for underwater diving and similar applications. A diving depth gauge is a pressure gauge that displays the equ ...

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, islands of the Subantarctic, and the Antarctic Peninsula, primarily in rocky coastal regions, but locally also at ...

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