The black-necked swan (''Cygnus melancoryphus'') is a species of

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which in ...

in tribe

Cygnini Swans are birds of the family Anatidae within the genus ''Cygnus''. The swans' closest relatives include the geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometim ...

of subfamily

Anserinae The Anserinae are a subfamily in the waterfowl family Anatidae. It includes the swans and true geese. Under alternative systematical concepts (see e.g., Terres & NAS, 1991), it is split into two subfamilies, the Anserinae contain the geese and ...

.HBW and BirdLife International (2021) Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 6. Available at: http://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v6_Dec21.zip retrieved August 7, 2022 It is found in

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 ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

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 ...

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 ...

, and 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 ...

.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 July 2022. Species Lists of Birds for South American Countries and Territories. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved July 24, 2022

Taxonomy and systematics

The black-necked swan has occasionally been placed by itself in genus ''Sthenelides''. Its closest relatives are the

black swan The black swan (''Cygnus atratus'') is a large waterbird, a species of swan which breeds mainly in the southeast and southwest regions of Australia. Within Australia, the black swan is nomadic, with erratic migration patterns dependent upon c ...

(''C. atratus'') and

mute swan The mute swan (''Cygnus olor'') is a species of swan and a member of the waterfowl family Anatidae. It is native to much of Eurosiberia, and (as a rare winter visitor) the far north of Africa. It is an introduced species in North America, home ...

(''C. olor''). It 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 ...

Description

The black-necked swan is the only member of its genus that breeds in the

neotropic The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In bioge ...

s, and is the largest waterfowl native to South America. Adults are long with a wingspan of . Males weigh and females . The sexes are alike. Adults' body plumage is white and the neck and head black; the latter usually has a white stripe behind the eye. They have a prominent red knob at the base of their bill. Juveniles are grayish rather than white and lack the knob until their third or fourth year.

Distribution and habitat

The black-necked swan is found in the southern tier of South America. It nests from

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 ...

north to central Chile, Uruguay, and

Rio Grande do Sul Rio Grande do Sul (, , ; "Great River of the South") is a Federative units of Brazil, state in the South Region, Brazil, southern region of Brazil. It is the Federative_units_of_Brazil#List, fifth-most-populous state and the List of Brazilian st ...

in extreme southern Brazil. It withdraws from the southern half of Argentina in winter and is then found as far north as Brazil's

São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC a ...

state. It is a year-round resident of the Falkland Islands.

Vagrants Vagrancy is the condition of homelessness without regular employment or income. Vagrants (also known as bums, vagabonds, rogues, tramps or drifters) usually live in poverty and support themselves by begging, scavenging, petty theft, temporar ...

have been found on Juan Fernández Island, the

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 Peninsula 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 195 ...

, and 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 ...

. The wetlands created in Chile by the

1960 Valdivia earthquake The 1960 Valdivia earthquake and tsunami ( es, link=no, Terremoto de Valdivia) or the Great Chilean earthquake (''Gran terremoto de Chile'') on 22 May 1960 was the most powerful earthquake ever recorded. Various studies have placed it at 9.4– ...

, such as

Carlos Anwandter Nature Sanctuary Río Cruces Chorocamayo Nature Sanctuary (Spanish: Santuario de la naturaleza Carlos Anwandter) is protected wetland in Cruces River about north of Valdivia, Chile. The sanctuary is named after the German politician Carlos Anwandter who settled i ...

on the

Cruces River The Cruces River ( es, Río Cruces) is a river in south-central Chile. Río Cruces originates from hills near the Villarica volcano and flows then in south-west direction. The southern and final part of the river flows in a south-south-west di ...

, have become important population centers for the black-necked swan.Ramirez, C., E. Carrasco, S. Mariani & N. Palacios. 2006. La desaparición del luchecillo (''Egeria densa'') del Santuario del Rio Cruces (Valdivia, Chile): una hipótesis plausible. Ciencia & Trabajo, 20: 79-86 The black-necked swan inhabits freshwater

marshes A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

and swamps, shallow lakes, brackish

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

s, and sheltered coastal sites. On the mainland of South America it is often found near human habitation, but shuns built up areas in the Falklands. It is generally found at low elevation but non-breeding flocks can be found as high as in the Andes of southern Argentina.

Behavior

Feeding

The black-necked swan's diet is almost entirely vegetarian. It feeds on aquatic plants like '' Chara'', ''

Potamogeton ''Potamogeton'' is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed (''Elodea canadensis'' ...

'', ''

Typha ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in A ...

''; algae such as ''Aphantotece'' and ''Rhyzoclonium''; and presumably small numbers of aquatic invertebrates. In parts of Chile its principal food is ''

Egeria densa ''Egeria densa'', the large-flowered waterweed or Brazilian waterweed, is a species of '' Egeria'' native to warm temperate South America in southeastern Brazil, Argentina, Chile and Uruguay. It is considered a problematic invasive species due t ...

''. It forages mostly by immersing its head and neck and by surface feeding, but also upends to reach deeper. In times of drought it has been observed grazing in meadows and pastures.

Breeding

The black-necked swan's breeding season varies geographically. In the far south of its range it breeds from July to November but ends as early as September in the northern parts. In the Falklands it breeds between August and November. The exact timing of breeding appears dependent on rainfall. The species is believed to form long-term pair bonds. Its nest is a mound of vegetation constructed by both members of a pair on a small islet or partially floating in a reedbed. The clutch size is four to eight eggs. Males guard females during the 34 to 36 day incubation period. Captive nestlings fledged about 100 days after hatch.

Vocalization

The black-necked swan is mostly silent outside the breeding season. During that time both sexes give a "soft, musical 'Whee-whee-whee' with accent on initial syllable", repeating it to challenge intruders. The call is also used to maintain contact between members of a pair. Males also give "a musical 'hooee-hoo-hoo'."

Status and conservation

The

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 ...

has assessed the black-necked swan as being of Least Concern. It has a very large range, and though its population size is not known it is believed to be stable. No immediate threats have been identified. It is widespread and generally common. Large scale hunting in the 18th and 19th centuries extirpated it from much of Chile but it has recolonized those area. Some egg collecting and hunting still occur, however. The species occurs in several protected areas in mainland Argentina, in which country the population is estimated at 50,000.

Gallery

File:Blackneck swan pair hornopiren chile feb 2010.jpg File:Cygnus melanocoryphus at the Denver Zoo-2012 03 12 1029.jpg File:Cygnus melanocoryphus at the Denver Zoo-2012 03 12 1033.jpg File:Black Necked Swans at the Philadelphia Zoo (cropped).jpg File:Black-necked Swan SMTC.jpg File:Cygnus melancoryphus MHNT.ZOO.2010.11.11.1.jpg

References

External links

Stamps
(for Argentina, Brazil, Chile, Falkland Islands, Uruguay) with RangeMap

VIREO

black-necked swan The black-necked swan (''Cygnus melancoryphus'') is a species of waterfowl in tribe Cygnini of subfamily Anserinae.HBW and BirdLife International (2021) Handbook of the Birds of the World and BirdLife International digital checklist of the bird ...

Birds of Chile Birds of the Falkland Islands Birds of the Pampas Birds of Patagonia