Cygnus columbianus bewickii (Ord, 1815)
Bewick’s Swans are one of the smaller varieties of swan. Adult birds have uniformly white feathers and distinctive black and yellow markings on their bill with the yellow ending behind the nostrils. This pattern is so distinctive that birds may be recognised individually. They have short, straight necks, round heads and black legs. Juvenile birds have grey feathers and black and pink bill patterns. The birds will gradually become white within two years of hatching as they mature. Birds in their second and sometimes third year may retain some grey feathers on their head and neck and pink patches on the bill.
The Bewick’s Swan has a soft bugling call with musical notes. They are very vocal throughout the year, especially on water and in flight. Calls are used for a range of territorial and contact purposes. Loud calls are used for threat and triumph ceremonies, quieter calls are used for greetings and as pre-flight signals, honking calls are used in flight while gentle babbling calls are common during resting.
Bewick’s moult their flight feathers in July-August every year.
Bewick’s Swans breed in arctic Russia on a narrow band of tundra stretching from the Kanin Peninsular west to the Chukotka Sea. Three populations have been identified based on their winter distribution: the Northwest European, the Eastern and the Caspian.
Northwest European population This population breeds to the west of the Ural Mountains in Arctic Russia and winters in Northwest Europe, mainly in the Netherlands, the UK and Germany with smaller numbers found in Belgium, Denmark, Sweden, 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.
Eastern population This population breeds in Arctic Russia to the east of the Lena Delta and winters mainly in Japan, China and Korea. An estimated 75% of the population winter in the Yangtze River floodplain in China (Cong et al. 2011).
Historically the population was more widely distributed throughout the floodplain but now most of the population is confined to five wetlands in Anhui Province and to Poyang Lake in Jiangxi Province, where the majority (up to 113,000 birds) occur.
Caspian population The breeding range in arctic Russia is unknown but is thought to fall just to the east of the Ural Mountains in Arctic Russia. Swans from this smaller population winter in and around the Caspian and Aral Seas, and in smaller numbers in Iran, Turkey and the Ukraine. There is likely to be some cross-over between the Northwest European and Caspian populations.
There may be some overlap in the distribution of the three populations in arctic Russia during the summer time.
|Population||Year of latest pop. estimate||Population size||Data types||Trend years||Trend||Trend quality||1% threshold||Source|
|NW European||2005 – 2005||21,500 – 21,500||Census based||1997 – 2007||DEC||Good||220||(1), (2)|
|Caspian||1990 – 2000||1,000 – 1,000||Expert opinion||1990 – 2000||STA||No idea||10||(1)|
|Eastern (jankowskii)||2007 – 2007||92,000 – 110,000||Expert opinion||0 – 0||Unknown||No idea||1000||(3)|
From: (1) BirdLife Review (2012), (2) Wetlands International (2012), (3) Cao et al. (2008).
The Bewick’s Swan breeds adjacent to shallow lakes and pools on the Arctic tundra, particularly on sedge-grass and moss-lichen tundra dotted with numerous small lakes and pools, and also in some dry land areas with willow bushes. At the breeding grounds it feeds mostly on sedge and other herbs and berries, as well as on algae and Potamogeton. On migration the species requires a chain of stop-over sites including shallow coastal lakes with soft sediment and good water quality as well as flooded grasslands. In winter the species traditionally occupies shallow tidal waters, coastal lagoons, inland freshwater lakes and marshes and flooded pastures, where they mostly feed on the tubers and rhizomes of Potamogeton spp., on Zostera spp. And Chara spp., and also on grasses and herbs. From the 1970s onwards, an increasing proportion of the Northwest European population has fed on arable land during the winter.
Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA, 2015) Appendix II of the Convention on the Conservation of the European Wildlife and Natural Habitats (Bern Convention) Appendix II of the Convention on Migratory Species (CMS or Bonn Convention) Annex I of the EU Birds Directive Wildlife and Countryside Act (1981) (Wetlands International and The Wildfowl & Wetlands Trust (WWT), 2012).
IUCN Red List Assessment
Least Concern (LC). Assessed at species level (C. columbianus) and not at sub-species level (C. columbianus bewickii)
Human hunting for sport and food. Taken for pets and animal displays (BirdLife International, 2012). Climate change & severe weather Habitat shifting & alteration Lead poisoning due to ingested lead fishing weights, lead shot and lead contaminated sediments (del Hoyo et al., 1992); Kear 2005). Overhead lines collisions (del Hoyo et al. 1992) Avian influenza (Melville and Shortridge, 2006) Arctic breeding habitat threatened by oil and gas leaks (Kear, 2005).
Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) (2015). Cygnus olor. Available from: http://www.unep-aewa.org/en/species/cygnus-olor [Accessed 7 March 2016]
BirdLife International (2012). Cygnus columbianus bewickii. The IUCN Red List of Threatened Species 2012. Available from: http://www.iucnredlist.org/details/full/22679862/0 [Accessed 7 March 2016]
del Hoyo, J.; Elliot, A.; Sargatal, J. (1992). Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.
Kear, J. (2005). Ducks, geese and swans volume 1: general chapters; species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, U.K.
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.
Wetlands International and The Wildfowl & Wetlands Trust (WWT) (2012). International Single Species Action Plan for the Conservation of the Bewick’s Swan. 44, pp. 17.