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 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 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.

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 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, the the calls sometimes lower pitched in males.  The calls are 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: Bewick’s Swans breed in arctic Russia on a band of tundra stretching from the Kanin Peninsular west to the Chukotka Sea. There are three populations: the Northwest European, the Eastern and the Caspian.

Icelandic population: This population breeds to the west of the Ural Mountains and winters in Northwest Europe, mostly in the Netherlands, the UK and Germany and in smaller numbers in Belgium, Denmark, France and Ireland.  There are important staging sites in the Netherlands, Germany and the Baltic countries, especially Estonia in both spring and autumn and the White Sea region in the spring.

Northwest Continental European population: This population breeds across northern Scandinavia and northwest Russia, wintering to the south – mainly in continental Europe and as far west as south western England.

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: Over wintering between the Caspian Sea and Lake Balkhash, believed to breed in central Siberia (Mathiasson, 1991; Scott and Rose, 1996).

E. 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 and Scott, 1997). Migration routes are not as yet fully understood with ongoing ringing programmes in eastern Russia and Japan.

Population Year of latest pop. estimate Population size Data types Trend years Trend Trend quality 1% threshold Source
Icelandic/Britain & Ireland 2005 26,500 – 26,500 Census 1997 – 2007 INC Good 270 (1)(2)
Northwest Mainland Europe 1995 59,000 Census 1995 – 2005 INC Good 590 (1)(3)
N Europe & W Siberia/Black Sea & E Mediterranean 1983 12,000 Expert opinion 1996 – 2006 Not known No idea 120 (1)(4)
West & Central Siberia/Caspian 1990 – 1995 20,000 Expert opinion 1984 – 1994 DEC Poor 200 (1)(5)
E Asia 2000 60,000 0 – 0 Not known No idea 600 (1)(6)

From: (1) Wetlands International (2014), (2) Worden et al. (2006), (3) Laubek et al. (1999),  (4) Ruger et al.  (1986), (5) Scott & Rose (1996), and (6) 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 700 m.  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 1960s.  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: Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA, 2015).

IUCN Red List Assessment: Least Concern (LC)

Current population trend: Unknown

Threats: Human hunting for sport and food. Taken for pets and animal displays. Climate change and severe weather. Habitat shifting & alteration (BirdLife International, 2012). Lead poisoning due to ingested lead fishing weights and lead shot (Spray and Milne (1988). Overhead lines collisions or wind turbines (Kear, 2005; Larson and Clausen, 2002) Avian influenza (Melville and Shortridge 2006).

References

Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) (2015). Cygnus cygnus. Available from: http://www.unep-aewa.org/en/legalinstrument/aewa [Accessed 7 March 2016]

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 7 March 2016]

Black, J.M. (1988) Preflight Signalling in Swans: A Mechanism for Group Cohesion and Flock Formation. Ethology. 79. pp.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.

Kear, J. (2005) Ducks, geese and swans volume 1: general chapters; species accounts (Anhima to Salvadorina). 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. In: Rees, E. C.; Earnst, S. L.; Coulson, J. (ed.), Proceedings of the 4th International Swan Symposium, pp. 327-330. Waterbird Society

Laubek, B., Nilsson, L., Wieloch, M., Koffijberg, K., Sudfelt, C. and 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. pp.141-154.

Mathiasson, S. (1991). Eurasian Whooper Swan Cygnus cygnus migration, with particular reference to birds wintering in southern Sweden. Wildfowl Spec. Suppl., 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.

Pennycuick, C., Einarsson, O., Bradbury, T.A.M. and Owen, M. (1996) Migrating whooper swans Cygnus cygnus: satellite tracks and flight performance calculations. Journal of Avian Biology. 27. pp.118-134.

Rees, E.C., J.S. Kirby & A. Gilburn. (1997) Site selection by swans wintering in Britain; the importance of habitat and geographic location. Ibis. 139 (2). pp.337-352.

Rose, P.M. and Scott, D.A. (1997) .Waterfowl population estimates, (2nd edn), Publ., No. 44.Wetlands International, Wageningen, Netherlands.

Ruger, A., Prentice, C. and Owen, M. (1986) Results of the International Waterfowl Census 1967-1983. IWRB Spec. Publ. 6. Slimbridge, UK.

Ruger, A., Prenticw, C. and Owen, M. (1986). Results of the International Waterfowl Census 1967-1983. IWRB Spec. Publ. No. 6. 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. and Rose, P.M. (1996) Atlas of Anatidae populations in Africa and western Eurasia. Wetlands International Publication 41. Wetlands International, Wageningen, NL. pp.336.

Wetlands International (2016) Waterbird Population Estimates. Available from: wpe.wetlands.org [Accessed Friday 5 Feb 2016].

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) pp.22.