Black-necked Swan Cygnus melancoryphus Scientific name definitions

The Black-necked Swan is the only species of true swan (Cygnus) that breeds in the Neotropics. The plumage is mostly white, apart from the black neck and head; this swan also has a prominent red knob at the base of the bill. The juvenile is similar in pattern to the adult, but the body plumage is grayish, not white, and the head and neck are dusky gray, not black. This swan breeds in emergent vegetation fringing freshwater lakes, but at other times of the year occurs on both freshwater and brackish lakes, as well as in bays and fjords. This species usually is gregarious, and often is in small flocks, although sometimes occurring in aggregations of up to several thousand. The Black-necked Swan is resident throughout much of its range, but some of the southernmost populations are migratory.

102–124 cm; male 4600–8700 g, female 3500–4400 g (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Unmistakable. Variable white stripe behind eye (sometimes it is completely absent) (2 Seijas, M.S. (1996). Identificacion individual en el Cisne de Cuello Negro (Cygnus melancoryphus) a traves de la linea ocular. Ornitología Neotropical. 7(2): 171-172. Close ). Female slightly smaller. Juvenile  lacks knob  (which only becomes fully developed when 3–4 years old) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) and has varying amounts of greyish- and brownish-tipped feathers.

S South America from Tierra del Fuego and Falkland Is N to C Chile, Uruguay and extreme S Brazil (Rio Grande do Sul); in winter N to São Paulo, in SE Brazil.

Swamps, river basins (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), freshwater marshes, lagoons of brackish water, shallow lakes and inlets, and sheltered coastal sites, often in close proximity to human habitation on South American continent, but not in Falklands (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Usually prefers waters with rich submerged vegetation (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ). Largely restricted to low altitudes, but reaches lower valleys of Andes and non-breeders may gather to moult on lakes in Andean foothills of W Santa Cruz and Chubut, S Argentina (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ), e.g. the Strobel Plateau at 900–1250 m (5 Lancelotti, J.L., Pozzi, L.M., Márquez, F., Yorio, P. and Pascual, M.A. (2009). Waterbird occurrence and abundance in the Strobel Plateau, Patagonia, Argentina. El Hornero. 24(1): 13–20. Close ).

Falklands and northern populations relatively sedentary, though movements to favoured estuaries reported (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), but those from higher latitudes descend to lower ones in winter (from Mar–Apr) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), occurring as far N as Tropic of Capricorn and perhaps even further N, given one unconfirmed record in Rio de Janeiro state, SE Brazil (6 Sick, H. (1997). Ornitologia Brasileira. Editora Nova Fronteira, Rio de Janeiro, Brazil. Close ); no confirmed records from Paraguay, although suspected to occur as an austral migrant (7 Hayes, F. E. (1995). Status, Distribution and Biogeography of the birds of Paraguay. Monographs in Field Ornithology 1. American Birding Association, Colorado Springs, CO, USA. Close ). El Niño South Oscillation (ENSO) events can also affect behaviour, at least at some sites in Chile, where in non-ENSO years swans reached their maximum numbers in winter and where absent in summer, whereas in ENSO years the birds remained year-round and bred (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Seasonal fluctuations in water levels account for some local movements, as smaller wetlands often dry out in summer, forcing swans to congregate on more major and permanent waterbodies (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Vagrants (sometimes in small groups) (8 Orgeira, J.L. and Fogliatto, O.N. (1991). The Blacknecked Swan Cygnus melanocoryphus in Antarctica. Marine Orn.. 19(1): 140-143. Close ) have been recorded on Juan Fernández Is (Chile), the South Orkney Is (9 Coria, N. R., D. Montalti, E. F. Rombola, M. M. Santos, M. I. Garcia Betoño, and M. A. Juares (2011). Birds at Laurie Island, South Orkney Islands, Antarctica: breeding species and their distribution. Marine Ornithology 39(2):207–213. Close ), South Shetland Is (10 Aguirre, C.A. (1995). Distribution and abundance of birds at Potter Peninsula, 25 de Mayo (King George) Island, South Shetland Islands, Antarctica. Marine Orn.. 23(1): 23–31. Close , 11 Silva, M.P., Coria, N.R., Favero, M. and Casaux, R.J. (1995). New records of Cattle Egret Bubulcus ibis, Blacknecked Swan Cygnus melancoryphus and Whiterumped Sandpiper Calidris fuscicollis from the South Shetland Islands, Antarctica. Marine Orn.. 23(1): 65–66. Close , 12 Hahn, S., H.-U. Peter, P. Quillfeldt, and K. Reinhardt (1998). The birds of the Potter Peninsula, King George Island, South Shetland Islands, Antarctica, 1965–1998. Marine Ornithology 26(1–2):1–6. Close ) and the Antarctic Peninsula (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) (S as far as 68º S) (8 Orgeira, J.L. and Fogliatto, O.N. (1991). The Blacknecked Swan Cygnus melanocoryphus in Antarctica. Marine Orn.. 19(1): 140-143. Close ), at least some of which events appear to have been promoted by severe droughts on the South American mainland (8 Orgeira, J.L. and Fogliatto, O.N. (1991). The Blacknecked Swan Cygnus melanocoryphus in Antarctica. Marine Orn.. 19(1): 140-143. Close ); occasionally birds were emaciated and died (13 Milius, N. (2000). The birds of Rothera, Adelaide Island, Antarctic Peninsula. Marine Orn.. 28(1): 63–67. Close ), or were predated by Brown Skuas (Catharacta antarctica) (9 Coria, N. R., D. Montalti, E. F. Rombola, M. M. Santos, M. I. Garcia Betoño, and M. A. Juares (2011). Birds at Laurie Island, South Orkney Islands, Antarctica: breeding species and their distribution. Marine Ornithology 39(2):207–213. Close ).

Eminently vegetarian , mainly stoneworts (Chara) and pondweeds (Potamogeton), as well as other aquatic weeds (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ); also algae and presumably some aquatic insects and other aquatic invertebrates and fish spawn. In some areas of Chile appears strongly dependent on Egeria densa, which is dominant submerged plant, but elsewhere in the same country commonest such plants are Myriophillum and Lemno-Azolletum, while in Uruguay suitable food plants include Scirpus, Typha, Potamogeton and algae such as Aphantotece, Rhyzoclonium and Enteromorpha (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Forages principally by immersing head and neck, or by surface-feeding (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), but also by upending (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ) and occasionally by grazing on meadows and pastures during periods of drought (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Generally considered to be silent or almost so outside breeding season (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ). Gives soft, musical “Whee-whee-whee” with accent on initial syllable, which may be uttered repeatedly in presence of intruders and during “Triumph Display” by pairs, and is also used in contact, both on water and in flight (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Sexes stated to have similar calls (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), although only male is reputed to give a musical “hooee-hoo-hoo” (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ). Those of cygnets are generally similar to those of other young swans, but are considered to be more goose-like and lighter in tone than those of Northern Hemisphere Cygnus (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Starts in early spring (Jul–Aug, occasionally Jun) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), but continues until at least Sept–Nov in far S of range (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ); starts early Aug to mid Sept on Falklands (14 Woods, R. W., and A. Woods (1997) Atlas of Breeding Birds of the Falkland Islands. Anthony Nelson, Oswestry, UK. Close ); Sept in extreme S Brazil (15 Belton, W. (1984). Birds of Rio Grande do Sul, Brazil. Part 1. Rheidae through Furnariidae. Bulletin of the American Museum of Natural History 178(4): 369–636. Close ). Captive birds in Northern Hemisphere will start breeding in Feb–Mar, or even Jan in mild winters (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Rainfall affects breeding cycle (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). May occasionally be double-brooded (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) and probably forms long-term pair-bonds (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). In single pairs or loose groups, despite territorial behaviour of breeding birds and perhaps reflecting lack of other suitable nearby breeding sites (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), with mean distance between nests 13·6 m (range 1·7–32 m) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); nest is large mound of vegetation, in reedbeds or partially floating, preferably on small islets, and is constructed by both sexes (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Clutch 4–8 cream-coloured (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) eggs, size 95–106·2 mm × 63·6–69·5 mm, mass 172·5–273·5 g (captivity) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); incubation c. 34–36 days by female, guarded by male (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); chicks have greyish-white down and are guarded by both adults (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); fledging c. 100 days (captivity), tended by both adults (4 Fjeldså, J., and N. Krabbe (1990). Birds of the High Andes: A Manual to the Birds of the Temperate Zone of the Andes and Patagonia, South America. Zoological Museum, University of Copenhagen and Apollo Books, Copenhagen and Svendborg, Denmark. Close ). Kelp Gulls (Larus dominicanus) perhaps predate eggs in Falklands, while Southern Caracaras (Caracara plancus) can inflict significant losses on both eggs and cygnets in Chile (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Single record of brood of 12 cygnets, perhaps reflected adoption (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Captive-bred birds may nest successfully when two years old (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). In Chile, apparently just 7·6–16·7% of population breeds each year, with mean brood sizes of 1·5–2·8 cygnets per pair depending on site and year (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Maximum recorded lifespan in captivity 20 years (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Not globally threatened (Least Concern). CITES II. In late 1990s total population perhaps < 100,000 birds (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Generally common and widespread; has recolonized parts of Chile where had been eradicated by hunting and trapping for skins and feathers (used for female clothing and powders puffs in Europe) in late 18th and 19th centuries (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), while earthquakes in S of country in 1960 enabled colonization of coastal region between Valdivia and Chiloe I (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Nevertheless, some egg-collecting, hunting and disturbance at wetlands occurs, despite legal protection of sites in Chile since early 1980s, while wardening schemes have led to major local increases (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Known from several protected areas in southernmost mainland Argentina (16 Darrieu, C. A., A. R. Camperi, and S. Imberti (2008). Avifauna (non Passeriformes) of Santa Cruz province, Patagonia (Argentina): annotated list of species. Revista del Museo Argentino de Ciencias Naturales 10:111–145. Close ). Largest concentrations on record, 5000 birds at Laguna de Chascomús, Argentina, 10,000 at Banados del Este wetlands, SE Uruguay (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) and in late Apr 1995 an exceptional 20,000 at Puerto Natales, S Chile (17 Vuilleumier, F. (1997). A large autumn concentration of swans (Cygnus melancoryphus and Coscoroba coscoroba) and other waterbirds at Puerto Natales, Magallanes, Chilean Patagonia, and its significance for swan and waterfowl conservation. Ornitología Neotropical. 8(1): 1-5. Close ). Estimated populations: Brazil , 2000–3000 birds; Uruguay, 20,000; Argentina, 50,000; and Chile , 20,000. Uncommon breeding resident in Falkland Is, with an estimated 300–600 pairs in 1983–1993 (14 Woods, R. W., and A. Woods (1997) Atlas of Breeding Birds of the Falkland Islands. Anthony Nelson, Oswestry, UK. Close ) and concentrations of c. 100 in most favourable spots during non-breeding season. Drainage of marshy areas is main threat; is not a typical quarry species.