Coscoroba Swan Coscoroba coscoroba Scientific name definitions

The smallest species of swan, Coscoroba Swans are still one of the largest species of waterfowl in South America. They inhabit swamps, lakes, lagoons and other bodies of fresh water in southern South America. This species is a partial migrant, breeding in southern Chile and Argentina south to Tierra del Fuego, and then moving north in winter; the bulk of the population winters in central and northern Chile and Argentina and Uruguay, with individuals make it as far north southeastern Brazil. There is also a population on the Falkland Islands.

Coscoroba Swans are more goose-like in appearance than their Northern Hemisphere relatives. Both sexes are all white, with black wingtips and red bills and legs. The Coscoroba Swan is one of only two all-white waterfowl in South America. The other all-white species, the male Kelp Goose Chloephaga hybrida, is much smaller, inhabits rocky coastlines, and lacks the red bill and legs of the Coscoroba Swan.

Though its population was estimated at around 100,000 individuals, BirdLife International has listed the Coscoroba Swan as a species of Least Concern; habitat destruction and degradation through the diversion of wetlands are the chief threats to this species.

90–115 cm; male 3800–5400 g, female 3100–4500 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 ). The smallest swan. Black tips to six outermost primaries  . Breast feathers appear centrally parted. Female has brown iris and is smaller than male (wing 415–477 mm versus 440–498 mm in 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 ). Juvenile  similar to female, but brownish on head and upperparts  , before developing adult plumage by eight months 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 ); bill blue-grey (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 ); bare-parts coloration much like adult by five months (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 birds apparently larger than those in N, e.g. in S Brazil, wing of male is just 375–390 mm (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 South America from Tierra del Fuego and Falkland Is N to C Chile and N Argentina; winters N to Paraguay, SE Brazil and probably in Bolivian Chaco, where recently recorded (2 Tobias, J.A. and Seddon, N. (2007). Ornithological notes from southern Bolivia. Bulletin of the British Ornithologists' Club 127(4): 293–300. Close ).

Favours lagoons and large freshwater swamps, preferably those with well-vegetated margins, but has also been recorded at man-made reservoirs (3 Echevarria, A.L., Cocimano, M.C., Chani, J.M. and Marano, C.F. (2013). Nesting biology of Coscoroba Swan Coscoroba coscoroba at La Angostura Dam, Tafí del Valle, Tucumán, Argentina. Cotinga. 35: 13-16. Close ). Occurs mainly in lowlands with scattered breeding records to 1300 m and one at 2000 m in NW Argentina (Tucumán) (3 Echevarria, A.L., Cocimano, M.C., Chani, J.M. and Marano, C.F. (2013). Nesting biology of Coscoroba Swan Coscoroba coscoroba at La Angostura Dam, Tafí del Valle, Tucumán, Argentina. Cotinga. 35: 13-16. Close ), and the species has occasionally been recorded up to 1000 m in Andean foothills of Santa Cruz (S Argentina) (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 ).

Some southern breeders migrate to lower latitudes (c. 25º S) in winter, exceptionally N of the Tropic of Capricorn, but other populations usually considered to be mainly sedentary, including those in Magellanic region and NW Isla Grande is considered an important wintering area (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 ). However, in neighbouring Chile, where the species was formerly considered rare winter visitor in early 20th century (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 ), the species is now mainly a winter visitor to C Chile, breeding in S of country (4 Jaramillo, A. (2003). A Field Guide to the Birds of Chile Including the Antarctic Peninsula, the Falkland Islands and South Georgia. Christopher Helm, London, UK. Close ). Marked movement, with Cygnus melanocoryphus, into Uruguay during 1988/89 was attributed to drought further S, mostly from Argentina (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 ). Long-term banding study (involving 1070 birds) in S Brazil has revealed heretofore unsuspected level of movements, including one bird that was recovered in Chubut, S Argentina (04º S), although it seems that males are perhaps more faithful to their natal area, but juveniles are clearly capable of widespread dispersal prior to their achieving sexual maturity (5 Calabuig, C.P., Green, A.J., Menegheti, J.O., Abad, R.M. and Patiño, J. (2010). Fenología del Coscoroba (Coscoroba coscoroba) en el sur de Brasil y sus movimientos hacia Argentina. Ornitología Neotropical. 21(4): 555–566. Close ). Although occasionally breeds in Falklands (c. 1860, display observed Nov 1994) (6 Woods, R. W., and A. Woods (1997) Atlas of Breeding Birds of the Falkland Islands. Anthony Nelson, Oswestry, UK. Close ), mainly a visitor to the islands, sometimes in small flocks (7 Woods, R. W. (1988). The Birds of the Falkland Islands. Anthony Nelson, Oswestry, England. Close ), with an influx noted in Nov 1998 (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 have been recorded several times outside usual range in Brazil, in Santa Catarina  (one undated, the other records in 1978, 1990 and 1991) (8 Rosário, L. A. (1996). As Aves em Santa Catarina. Distribuição Geográfica e Meio Ambiente. FATMA, Florianópolis, Brazil. Close ), several times (including large flocks) in Paraná (1990 (9 Bornschein, M.R., Reinert, B.L. and Pichorim, M. (1997). Notas sobre algumas aves novas ou pouco conhecidas no sul do Brasil. Ararajuba. 5(1): 53–59. Close ), 1996, 2002, 2003) (10 Gomes, A.B., Wasilewski, M. and Scherer Neto, P. (2004). Ocorrêncía do cisne-coscoroba Coscoroba coscoroba na Baía de Guaratuba, Paraná. Atualidades Orn.. 117: 11. Close ) and three times in Mato Grosso do Sul  (in 1988–1990) (11 Sick, H. (1997). Ornitologia Brasileira. Editora Nova Fronteira, Rio de Janeiro, Brazil. Close ), while there is one confirmed record in Bolivia , in Departamento Santa Cruz, in Jul 2006 (12 Tobias, J. A., and N. Seddon (2007). Ornithological notes from southern Bolivia. Bulletin of the British Ornithologists’ Club 127(4):293–300. Close ).

Apparently varied diet (but no detailed studies), consisting of plant matter, small aquatic and marine (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 ) invertebrates, fish spawn, etc. Forages mainly in shallow water, by swimming and dabbling or wading, but also grazes on land; does not upend as frequently as other swans (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 ). Regularly forms mixed flocks with Cygnus melanocoryphus (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 ).

Onomatopoeic “cos-cor-oo”  is usually given in threat display against intruders (but is not accompanied by “Triumph Display” typical of other swans), and also a monosyllabic hooting note, often uttered by male and female alternately, is used in contact; notes are similar in the sexes, but are noticeably higher-pitched in the male  (whereas in most swans it is females that are higher-pitched), while immatures give loud chirps and trills (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 ).

During local spring; May–Oct in NW Argentina (3 Echevarria, A.L., Cocimano, M.C., Chani, J.M. and Marano, C.F. (2013). Nesting biology of Coscoroba Swan Coscoroba coscoroba at La Angostura Dam, Tafí del Valle, Tucumán, Argentina. Cotinga. 35: 13-16. Close ), Jul–Dec in Chile (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ), Jul–Aug in S Brazil (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 ), or May–Dec over entire breeding range (i.e. one month earlier on average than C. melanocoryphus) and young hatch as late as Feb in C 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 ). Monogamous and usually 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 ), although extra-pair copulations were observed twice in one recent study (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ). Usually in single pairs, though nests sometimes just 10–18 m apart (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ) in prime habitat and occasionally breeds within C. melanocoryphus colonies (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 aquatic vegetation  (sometimes mainly constructed 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 ) well lined with soft grasses and down situated on small islands, in reedbeds or in long grass, close to water, and pairs sometimes build multiple nests (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ), although may re-use same nest in subsequent seasons (3 Echevarria, A.L., Cocimano, M.C., Chani, J.M. and Marano, C.F. (2013). Nesting biology of Coscoroba Swan Coscoroba coscoroba at La Angostura Dam, Tafí del Valle, Tucumán, Argentina. Cotinga. 35: 13-16. Close ); territory size in C Chile c. 0·25–7 ha (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ). In NW Argentina, nests were close to (within c. 1–7 m) the shoreline, in water 12–50 cm deep, on marshy soil, of mud and aquatic plants (Ludwigia longifolia, Myriophyllum quitense), and mean nest height was 33·4 cm above water level, mean cup diameter was 33·6 cm and depth 13·9 cm; basal length was 78·4 cm and width 77·5 cm; nests were sometimes used by Andean Coot (Fulica ardesiaca) after they were abandoned by the swans (3 Echevarria, A.L., Cocimano, M.C., Chani, J.M. and Marano, C.F. (2013). Nesting biology of Coscoroba Swan Coscoroba coscoroba at La Angostura Dam, Tafí del Valle, Tucumán, Argentina. Cotinga. 35: 13-16. Close ). Apparently double-brooded in S Brazil and C Chile, where second clutches initiated when first broods are 40–50 days 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 ). Clutch 4–9 eggs  , white, size 82–94·5 mm × 52·9–67 mm, mean mass c. 167 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. 35 days by female alone 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 ); downy chicks mainly greyish white with three drab grey dorsal bands and black cap , grey bill with pink tip and pale pink feet tinged grey (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 ), cared for by both adults and fledge at 13 (captive) or c. 14 weeks (wild 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 ), and only reach adult size at c. 8 months, but sometimes remain with adults until 12 months old in C Chile (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ), even into second year in 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 ). Newly hatched young may be predated by Kelp Gulls (Larus dominicanus) (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ). Breeding success unknown, but mean brood size 5·32 in C Chile, with one case of brood amalgamation noted (and this phenomenon may be comparatively frequent) (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ). Adult survival in captivity up to 20 years (mean 7·3 years), while normal age of first breeding is unknown in wild, captive birds can breed when just one year old, more frequently at three 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. Still widespread and quite common locally, with an overall population estimated at < 25,000 birds in late 1990s (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 ); thought to be decreasing in some areas, especially in Chile, where listed as Endangered (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 may now be largely restricted as a breeder to extreme S , with total population reckoned at under 1000 birds in 1970s, although some 1000–2000 individuals were off Puerto Natales, S Chile, in Apr (late autumn) (14 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 ) and the local population at El Yali, C Chile, was estimated at 230–250 birds in Jul 2002 (c. 34% breeding pairs with territories, 29–33% non-territorial pairs and 33–38% mostly groups of young birds) (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ). Partial census of Jul 1990 gave 350 in Uruguay and 12,195 in Argentina, while partial census in May to early Jun 1998 of wetlands in Argentina and Uruguay found total of 4036 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 ). Large numbers occur in N of Isla Grande (Tierra del Fuego), but is far less common than sympatric <em>Cygnus melanocoryphus</em> , and in neighbouring Santa Cruz province, Argentina, is known from several protected areas (15 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 ). Brazilian population very poorly known, but suspected to be in danger of extinction (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 Paraguay mainly confined to Chaco region (16 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 ), while in SE Uruguay population estimated at up to 500 birds, including breeding pairs (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 ). Greatest threat seems to be loss of temperate marsh habitats due to urbanization and agricultural developments, especially as range always seems relatively patchy, and hunting never appears to be have been a significant threat (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 it has been observed within protected areas in Chile (13 Silva-García, C.M. and Brewer, G.L. (2007). Breeding behavior of the Coscoroba Swan (Coscoroba coscoroba) in El Yali wetland, central Chile. Ornitología Neotropical. 18(4): 573-585. Close ).