Whooper Swan
Cygnus cygnus (Linnaeus, 1758)
Appearance
The Whooper Swan is one of the larger swan species, with adults having all-white plumage. Like the smaller Bewick’s Swans, which occur in the same wintering areas, adults have a characteristic black-and-yellow bill, but in the Whoopers the yellow markings extends in a wedge-like shape from the base to or beyond the nostrils. Whooper Swans also have a relative upright posture in comparison with the Bewick’s and also the Mute Swans, with a slight kink at the base of the neck and a relatively long neck to overall body length. Legs and feet are generally black but may be pinkish grey or with pink spots on the feet.
Downy cygnets are pale grey in colour, with slightly darker crown, nape, shoulders and rump. Immature plumage on first fledging is grey-brown, darker on the crown. Individuals become progressively white, at varying rates, during their first winter, and may be difficult to age in the field by spring.
Voice
Highly vocal, both in summer and winter, with calls similar to those of the Bewick’s Swans but with a deeper, more sonorous, bugling tone. Strength and pitch varies with social context, ranging from loud persistent notes during aggressive encounters and triumph displays to softer “contact” noises between paired birds and families. During winter, calls are most frequent when establishing dominance in flocks on arrival at wintering site. During summer, pairs are vocal on defending territories in spring, and also in flight (Rees et al. 1997). Calls accompanying pre-flight head-bobbing, important for maintaining pair and family cohesion, became louder just before take-off, changing to a higher pitched sound once airborne (Black 1988). Downy young make high pitched squeaking calls when distressed; softer contact calls at other times.
Moult
Whoopers moult their flight feathers in the breeding range during July–August each year. Paired birds tend to moult asynchronously. Unlike Bewick’s Swans, where yearlings are identifiable by the traces of grey feathers, the plumage of most 2nd winter Whoopers is indistinguishable from that of adults. Those that do have a few remaining grey feathers can only be aged as yearlings in the hand.
Distribution
Whooper Swans breed in shrub-forest tundra and taiga zones across Eurasia, south of the Bewick’s Swans’ breeding range, extending from Iceland and northern Scandinavia in the west to the Pacific coast of Russia in the east. Five main populations have been described: the Icelandic population, Northwest Continental European population, Black Sea/East Mediterranean population, West & Central Siberia/Caspian population and East Asian Population. There is very little information available on the extent of movements by Whooper Swans between the Black Sea/East Mediterranean and the West & Central Siberia/Caspian regions, however, and these birds therefore are sometimes treated as a single Central Russian breeding population.
Icelandic population: This population breeds in Iceland and most migrate 800–1400 km across the Atlantic Ocean to winter mainly in Britain and Ireland. Around 1,000–1,500 birds stay in Iceland over winter, with numbers remaining varying with weather conditions and food supply.
Northwest Continental European population: This population breeds across northern Scandinavia and northwest Russia, with increasing numbers of pairs nesting further south (notably in the Baltic countries: Estonia, Latvia, Lithuania and Poland) in the early 21st Century (Boiko et al. 2014). The swans migrate south to winter, mainly in continental Europe, but some individuals are known to have reached southeast England (Laubek et al.).
Black Sea/East Mediterranean population: This population nests in western Siberia and possibly west of the Urals, there may be some degree of cross link with the West & Central Siberia/Caspian population.
West & Central Siberia/Caspian population: Thought to breed in central Siberia, and to winter between the Caspian Sea and Lake Balkhash (Mathiasson 1991; Scott & Rose 1996).
East Asia population: Dispersed widely during the summer months across northern China and the eastern Russian taiga and winters mainly in Japan, China and Korea (Kondratyev 1991; Rose & Scott 1997). Migration routes are not as yet fully understood but ringing and tracking programmes are underway in eastern Russia, China, Mongolia and Japan.
Population Status
| Population | Year of latest pop. estimate | Population size | Data types | Trend years | Trend | Trend quality | 1% threshold | Source |
| Icelandic/Britain & Ireland | 2015 | 34,000 | Census | 1997 – 2007 | INC | Good | 340 | (1)(2)(3) |
| Northwest Mainland Europe | 1995 | 59,000 | Census | 1995 – 2005 | INC | Good | 590 | (1)(4) |
| N Europe & W Siberia/Black Sea & E Mediterranean | 1983 | 12,000 | Expert opinion | 1996 – 2006 | Not known | No idea | 120 | (1)(5) |
| West & Central Siberia/Caspian | 1990 – 1995 | 20,000 | Expert opinion | 1984 – 1994 | DEC | Poor | 200 | (1)(6) |
| E Asia | 2000 | 60,000 | 0 – 0 | Not known | No idea | 600 | (1)(7) |
From: (1) Wetlands International (2018), (2) Worden et al. (2006), (3) Hall et al. (2016), (4) Laubek et al. (1999), (5) Ruger et al. (1986), (6) Scott & Rose (1996), and (7) Miyabayashi & Mundkur (1999).
Habitat
Breeds mainly in sub-arctic and taiga zones, at more southerly latitudes than the Bewick’s Swan C. columbianus bewickii, adjacent to shallow lakes or pools (often on islets or peninsulas), or in marshes, usually in well-vegetated areas. May also nest on reed-fringed lakes in steppe regions, and reputedly on open arctic tundra (adjacent to Bewick’s Swan breeding territories) in some years. Diverse nesting habitat which, in Iceland, ranges from low-lying marshes in river deltas, sometimes adjacent to areas of improved farmland, to bogs and small pools amidst glacial moraine, and upland lakes, at altitudes of up to 700m. In Fenno-Scandia and Russia use swampy wetlands and pools with abundant emergent vegetation, surrounded by forests (including taiga and shrub-forest tundra). Also rivers, estuaries, coastal lagoons and reed-beds. Nest-sites well dispersed where swans breeding on discrete lakes; higher nesting densities found in the marshes. More accessible nest sites in Iceland than elsewhere in Europe may be due to a lower abundance of land predators in Iceland. Non-breeding flocks use pools and marshes until the moulting period, when they move on to open water, usually lakes, river channels or coastal bays, with rich bottom vegetation which can be reached by head-dipping or up-ending. Will also graze on land, particularly on arrival in the breeding range in spring.
Migrates on a broader front than C. c. bewickii, using lakes, estuaries, sheltered coasts and river systems as staging areas. In winter feeds mainly on aquatic vegetation in freshwater lakes, marshes, brackish lagoons and coastal bays, with increasing use of arable crops (stubble fields, winter cereals, sugar beet, potatoes; more recently oil seed rape) since the 1960’s. Also grazes on pasture (preferably damp or flooded), particularly in late winter and early spring. Areas of open water remain important for roosting throughout the range. Once thought to fly at high altitudes between Iceland and the UK; more recent evidence shows that the birds also migrate at just above sea level, and land on the sea in adverse weather or poor visibility (Pennycuick et al. in press). Shier than the Mute Swan Cygnus olor but has become habituated to man in some areas where non-interference is established. Human persecution and habitat loss in the 19th and first half of the 20th century seriously reduced numbers and breeding distribution in Fenno-Scandia and Russia, and also restricted the winter quarters. Much of the original breeding range in Sweden now reoccupied, and numbers breeding in Finland increasing, following introduction of conservation measures.
Protection
Legal protection from hunting introduced piecemeal by countries within range (e.g. 1885 in Iceland, 1925 in Japan, 1927 in Sweden, 1954 in UK, 1964 in Russia); extent to which law implemented remains variable, particularly in remote areas. Also protected under international conventions such as the European Community Birds Directive (Annex 1 species) and the Berne Convention (Appendix II species). Icelandic, Black Sea and West Asian populations also listed as Category A (2) in the Agreement on Conservation of African and Eurasian Waterbirds (AEWA) developed under the Convention of Migratory Species (CMS).
IUCN Red List Assessment
Least Concern (LC)
Threats
Historically Whooper Swan numbers were seriously reduced by human persecution during the 19th and 20th centuries, with breeding ranges reduced to areas above 67ON during the first half of the 20th century, but populations increased slowly following bans on hunting and egg collection. Current threats vary depending on location, with reasons for habitat degradation and loss including overgrazing by livestock, infrastructure development, reclamation of coastal and inland wetlands for farm expansion programmes, hydroelectric dam construction, disturbance from tourism, and oil spills (review in Kear 2005). Illegal hunting still occurs, and collision with powerlines is the most frequently reported cause of death for swans wintering in northwest Europe. Lead poisoning associated with the ingestion of lead shot or fishing weights remains an issue, with a high proportion of individuals tested having elevated blood lead levels (Spray & Milne 1988; Newth et al. 2016). The species is known to have contracted avian influenza, and is gregarious during winter, so may be threatened by future outbreaks of this and other infectious diseases (Melville & Shortridge 2006).
References
BirdLife International (2012). Cygnus cygnus. The IUCN Red List of Threatened Species 2012. Available from: http://www.iucnredlist.org/details/full/22679856/0#end_uses [Accessed Feb 2018].
Boiko, D., Kampe-Persson, H. & Morkŭnas, J. (2014). Breeding Whooper Swans Cygnus cygnus in the Baltic states, 1973–2013: result of a re-colonisation. Wildfowl 64: 207–216
Black, J.M. (1988) Pre-flight signalling in swans: a mechanism for group cohesion and flock formation. Ethology 79: 143-157.
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. (2014) HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions and BirdLife International.
Hall C., Crowe, O., McElwaine, G., Einarsson, Ó., Calbrade, N. & Rees. E. 2016. Population size and breeding success of the Icelandic Whooper Swan Cygnus cygnus: results of the 2015 international census. Wildfowl 66: 75– 97.
Kear, J. (2005) Ducks, Geese and Swans. Volume 1. Oxford University Press, Oxford, U.K.
Kondratyev, A.V. (1991). The distribution and status of Bewick’s Swan Cygnus bewickii,Tundra Swan C. columbianus and Whooper Swan C. cygnus in the Extreme Northeast of the USSR. Wildfowl Spec. Suppl., 1: 56–61.
Larsen, J. K. & Clausen, P. (2002). Potential wind park impacts on Whooper Swans in winter: the risk of collision. Waterbirds 25 (Special Publication No. 1): 327-330.
Laubek, B., Nilsson, L., Wieloch, M., Koffijberg, K., Sudfelt, C. & Follestad, A. (1999). Distribution, number and habitat choice of the Nothwest European Whooper Swan (Cygnus cygnus) population: results of an international Whooper Swan Census, January 1995. Vogelwelt 120: 141-154.
Mathiasson, S. (1991). Eurasian Whooper Swan Cygnus cygnus migration, with particular reference to birds wintering in southern Sweden. Wildfowl (Special Issue No. 1): 201–8.
Melville, D. S.; Shortridge, K. F. (2006). Migratory waterbirds and avian influenza in the East Asian-Australasian Flyway with particular reference to the 2003-2004 H5N1 outbreak. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 432-438. The Stationary Office, Edinburgh, UK.
Miyabayashi, Y. and Mundkur, T. (1999) Atlas of the Key Sites for Anatidae in the East Asian Flyway. Wetlands International, Tokyo, Japan, and Wetlands International Asia Pacific, Kuala Lumpur. pp.148.
Newth, J.L., Rees, E.C., Cromie, R.L., McDonald, R.A., Bearhop, S., Pain, D.J., Norton, G.J., Deacon, C., Hilton, G.M. 2016. Widespread exposure to lead affects the body condition of free-living whooper swans Cygnus cygnus wintering in Britain. Environmental Pollution 209: 60–67.
Pennycuick, C., Einarsson, O., Bradbury, T.A.M. & Owen, M. (1996) Migrating whooper swans Cygnus cygnus: satellite tracks and flight performance calculations. Journal of Avian Biology 27: 118-134.
Rees, E.C., Kirby, J.S. & Gilburn, A. (1997) Site selection by swans wintering in Britain; the importance of habitat and geographic location. Ibis. 139: .337-352.
Rose, P.M. & Scott, D.A. (1997). Waterfowl Population Estimates, Second Edition. , Wetlands International Publication No. 44. Wetlands International, Wageningen, Netherlands.
Ruger, A., Prentice, C. and Owen, M. (1986) Results of the International Waterfowl Census 1967-1983. IWRB Special Publication No. 6. IWRB, Slimbridge, UK.
Spray, C. J. & Milne, H. (1988). The incidence of lead poisoning among whooper and mute swans Cygnus cygnus and C. olor in Scotland. Biological Conservation 44: 265-281.
Scott, D.A. & Rose, P.M. (1996) Atlas of Anatidae populations in Africa and western Eurasia. Wetlands International Publication No. 41. Wetlands International, Wageningen, Netherlands.
Wetlands International (2018) Waterbird Population Estimates. Accessible at http://wpe.wetlands.org/ [Accessed Feb 2018].
Worden, J., Cranswick, P.A., Crowe, O., McElwaine, G and Rees, E.C. (2006) Numbers and distribution of Bewick’s Swan Cygnus colombianus bewickii wintering in Britain and Ireland: results of the International Censuses, January 1995, 2000 and 2005. Wildfowl 56: 3–25.
