Animal Diversity Web

Ge­o­graphic Range

Whooper swans (Cygnus cygnus) have an ex­ten­sive ge­o­graphic range and can be found within the bo­real zone in Eura­sia and many nearby is­lands. Bo­real con­di­tions often in­clude cold win­ters, short sum­mers, and dra­matic sea­sonal tem­per­a­ture vari­a­tions. Whooper swans breed in coun­tries such as Ice­land, Ire­land, and Great Britain and mi­grate in the win­ter to coun­tries such as China, Korea, and Japan. Some mi­gra­tory pop­u­la­tions can be found in India and west­ern North Amer­ica. (Birdlife In­ter­na­tional, 2012; Brazil, 2003)

• Biogeographic Regions
• nearctic
  • native
• palearctic
  • native
• oriental
  • native

Habi­tat

Whooper swans breed and set up nests along the banks of fresh­wa­ter lakes, pools, shal­low rivers, marshes, bogs, and swamps. They pre­fer habi­tats with emer­gent veg­e­ta­tion, which may pro­vide ad­di­tional pro­tec­tion for nests and new­born cygnets. In Ice­land, they are com­monly found in habi­tats rang­ing from sea-level to an el­e­va­tion of 700 m. Non-breed­ing pairs of swans can be found near shel­tered es­tu­ar­ies, la­goons, and shal­low bays. Mi­grat­ing whooper swans fly at al­ti­tudes of 500 to 1,700 m when cross­ing oceans, but often pre­fer fly­ing at lower lev­els to allow for fre­quent breaks be­tween flights. Near the British Isles, mi­grat­ing whooper swans have been recorded reach­ing heights above 8,000 m. (Brazil, 2003; Gar­dars­son and Skarphedins­son, 1984; Laubek, et al., 1999; Pen­ny­cuick, et al., 1996)

• Habitat Regions
• polar
• freshwater

• Terrestrial Biomes
• taiga

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• brackish water

• Wetlands
• marsh
• swamp
• bog

• Other Habitat Features
• agricultural
• riparian
• estuarine

Phys­i­cal De­scrip­tion

Both male and fe­male whooper swans have white plumage with black webbed feet and legs. Their beaks are or­ange-yel­low at the base with a black tip. The mark­ings on their beak can be used to dif­fer­en­ti­ate be­tween in­di­vid­u­als. In the spring and sum­mer, adults may de­velop dark neck plumage due to their iron-rich en­vi­ron­ment. Ju­ve­niles have downy grey-brown plumage with a pink and black tipped beak. Adult whooper swans are large birds, with an av­er­age length of 1.4 to 1.65 m and a wingspan of 2.05 to 2.75 m. Male weights range from 7.4 to 14 kg with an av­er­age of 9.8 kg, which is much heav­ier than the fe­male weight range of 8.2 to 9.2 kg. The high­est recorded mass was 15.5 kg for a win­ter­ing male swan in Den­mark. Aside from body mass, males can also be dif­fer­en­ti­ated from fe­males by their longer and thin­ner necks. A close rel­a­tive of whooper swans are the smaller, shorter-necked Be­wick swans. These swans can be dif­fer­en­ti­ated by beak color. Whooper swans have more or­ange-yel­low beak mark­ings while Be­wick swans have more black mark­ings. (Brazil, 2003; Dun­ning, 1992; Rees, et al., 1997)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  7.4 to 15.5 kg

  16.30 to 34.14 lb

• Average length

  1.4 to 1.65 m

  ft

• Average wingspan

  2.05 to 2.75 m

  ft

Re­pro­duc­tion

Whooper swans are monog­a­mous and form life­long pairs. In some cases, in­di­vid­u­als will find a new mate if their part­ner dies. Whooper swans can be ter­ri­to­r­ial dur­ing the breed­ing sea­son. Ri­vals some­times fight sav­agely by beat­ing their wings and, de­pend­ing on their lo­ca­tion, ei­ther ground star­ing or head-plung­ing. Courtship dis­plays can begin in the win­ter, but most occur in the sum­mer. Males and fe­males often bob their heads up and down as a greet­ing and then, with bod­ies fac­ing each other, turn their necks from left to right as they beat their wings fer­vently. Be­fore cop­u­la­tion oc­curs, pre-cop­u­la­tion dis­plays are short and in­clude head dip­ping and thrust­ing of their neck and chest into the water. Cop­u­la­tion is short and lasts around a minute. Dur­ing cop­u­la­tion, the male grasps the fe­male's nape. Cer­tain pairs par­tic­i­pate in post-cop­u­la­tion preen­ing. (Brazil, 2003)

• Mating System
• monogamous

Whooper swans breed once a year, their breed­ing sea­son be­gins in late April and early May. The ear­li­est eggs are laid in late April, but the ma­jor­ity of eggs are laid in May. Whooper swan eggs are large and el­lip­ti­cal with an off-white col­oration. Older eggs may be­come stained and turn brown after sev­eral days due to nest con­di­tions and iron-rich wa­ters. A sin­gle clutch is laid per year. Clutch sizes de­pend on the age of the pair and the re­source avail­abil­ity of their cho­sen breed­ing site. Younger cou­ples tend to be in­ex­pe­ri­enced and lay smaller clutches. Nests are often sit­u­ated on a large mound near a body of fresh water with ri­par­ian veg­e­ta­tion nearby for pro­tec­tion. In­cu­ba­tion lasts around 30 to 32 days and hatch­ing be­gins from June to early July. Not all pairs lay eggs, and not all eggs hatch. Cygnets are pre­co­cial and are cov­ered with down feath­ers when they hatch. They leave the nest 2 to 3 days after hatch­ing. After three months, chicks begin to fledge and are able to fly at 78 to 96 days. Fledg­lings be­come in­de­pen­dent after a year and be­come sex­u­ally ma­ture after about 4 years, which is an un­com­monly long time. Cygnet growth rates are im­pacted strongly by habi­tat qual­ity and food avail­abil­ity. (Black, 1996; Brazil, 2003)

• Key Reproductive Features
• iteroparous
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• oviparous

• Breeding interval

  Whooper swans breed once a year.

• Breeding season

  These swans begin breeding in late April and early May.

• Range eggs per season

  1 to 8

• Range time to hatching

  30 to 32 days

• Range fledging age

  78 to 96 days

• Average time to independence

  1 years

• Average age at sexual or reproductive maturity (female)

  4 years

• Average age at sexual or reproductive maturity (male)

  4 years

After the first egg is laid, the fe­male's main pri­or­ity is in­cu­ba­tion and the male's pri­or­ity is pro­tect­ing the nest and the sur­round­ing ter­ri­tory. Swans have long in­cu­ba­tion pe­ri­ods. Males rarely in­cu­bate the eggs, but they vig­i­lantly guard the nest by re­main­ing within 50 to 100 m from the nest. When fe­males take in­cu­ba­tion breaks to feed, the eggs are able to main­tain a con­stant tem­per­a­ture due to their larger size, which helps min­i­mize heat loss. The length of in­cu­ba­tion breaks in­crease as eggs ma­ture, and in­cu­ba­tion stops com­pletely sev­eral days be­fore hatch­ing. The first few days after hatch­ing, cygnets re­main close to the nest where they are taken care of by the fe­male. Un­like their close rel­a­tive, trum­peter swans, whooper swans do not carry their young on their backs. Mor­tal­ity rates are high for cygnets due to sus­cep­ti­bil­ity to cold weather, preda­tors, and in­ad­e­quate feed­ing. Par­ents help cygnets feed and re­main close to them in the early stages of de­vel­op­ment. Whooper cygnets stay within shaded areas near their par­ents until fledg­ing. Parental care de­clines as cygnets grow older and par­ents begin to spend less time with their heads above water and more time feed­ing. In gen­eral, males keep a vig­i­lant watch be­fore hatch­ing and fe­males take over that role dur­ing fledg­ing. After fledg­ing and be­fore in­de­pen­dence, the dis­tance be­tween cygnets and par­ents in­creases as the young be­come bolder and more ad­ven­tur­ous. How­ever, broods re­main to­gether even after fledg­ing. In­ter­est­ingly, if an early freeze oc­curs and cygnets are not yet able to fly, par­ents may leave their brood be­hind. This often re­sults in the cygnets' death due to the ab­sence of parental guid­ance. Cygnets tend to mi­grate with their par­ents until one year of age, and then par­ents restart the re­pro­duc­tion cycle. (Brazil, 2003)

• Parental Investment
• precocial
• male parental care
• female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
• pre-weaning/fledging
  • protecting
    • male
    • female
• pre-independence
  • protecting
    • male
    • female

Lifes­pan/Longevity

Adult whooper swans can live for decades. They have a small an­nual mor­tal­ity rate once they are past the first few weeks after hatch­ing. One com­mon cause of death oc­curs when wild whooper swans de­cide to con­tinue feed­ing off of agri­cul­tural ce­real grains in­stead of mi­grat­ing south to feed on aquatic veg­e­ta­tion. This shift in be­hav­ior has re­sulted in whooper swans freez­ing to death. How­ever, the great­est cause of adult and ju­ve­nile deaths is the re­sult of fly­ing ac­ci­dents. (Brazil, 2003)

• Range lifespan
  Status: wild

  20 (high) years

• Range lifespan
  Status: captivity

  25 (high) years

• Typical lifespan
  Status: wild

  10 to 15 years

• Typical lifespan
  Status: captivity

  12 to 16 years

Be­hav­ior

Whooper swans are ter­ri­to­r­ial dur­ing the sum­mer but so­cial dur­ing the win­ter. Whooper swans can be found liv­ing in flocks near wet­lands. Larger flocks of more than 40 in­di­vid­u­als are more com­mon from Oc­to­ber to No­vem­ber, whereas smaller flocks of fewer than 30 in­di­vid­u­als are more com­mon from Jan­u­ary to early spring. There is a so­cial hi­er­ar­chy with larger fam­i­lies at the top, monog­a­mous pairs in the mid­dle, and un­paired in­di­vid­u­als at the bot­tom. Dom­i­nant birds can feed for the longest pe­riod of time, and in­di­vid­u­als often seek to join flocks for added pro­tec­tion. Ag­gres­sive males may also cause one fam­ily to be more dom­i­nant over an­other fam­ily of equal size. Cygnets rarely ini­ti­ate flight, but they par­tic­i­pate in pre-flight sig­nal­ing to com­mu­ni­cate with their par­ents. (Brazil, 2003)

• Key Behaviors
• flies
• natatorial
• diurnal
• motile
• migratory
• social
• dominance hierarchies

• Range territory size

  0.7 to 5.7 km^2

Home Range

There is lit­tle in­for­ma­tion avail­able re­gard­ing the ter­ri­tory size de­fended by whooper swans, al­though some es­ti­mates sug­gest that it is as low as 0.7 km2, while oth­ers sug­gest it is as high as 5.7 km2. Breed­ing pairs gen­er­ally do not share a ter­ri­tory, how­ever, in some cir­cum­stances sev­eral pairs have been found shar­ing the same small body of water. (Brazil, 2003)

Com­mu­ni­ca­tion and Per­cep­tion

Whooper swans use sev­eral pre-flight sig­nals to in­di­cate that it is time to leave a cer­tain area. Com­mon move­ments in­clude 'head pump­ing', in­creased four-syl­labic call­ing, and wing flap­ping. Flocks con­tinue to in­crease sig­nal­ing to build ex­cite­ment and allow syn­chro­niza­tion to occur dur­ing take-off. Shortly after land­ing, whooper swans some­times par­tic­i­pate in greet­ing or tri­umph cer­e­monies, which in­clude head bob­bing, call­ing, and wing flap­ping. Due to the close­ness of these in­ter­ac­tions, greet­ing and tri­umph cer­e­monies can eas­ily tran­si­tion to ei­ther sex­ual or ag­gres­sive in­ter­ac­tions. Ag­gres­sion to­ward oth­ers can be dis­played by a com­bi­na­tion of ground star­ing, where the neck is arched and wings are spread slightly, bow-spit­ting, where the neck is held for­ward, and carpal flap­ping, where the wings flap vig­or­ously. In the case of con­spe­cific com­pe­ti­tion, a 'wa­ter-boil­ing' dis­play may occur, in which both swans out­stretch their wings be­fore phys­i­cal at­tacks are ini­ti­ated by both par­ties. (Brazil, 2003)

• Communication Channels
• visual
• tactile
• acoustic

• Other Communication Modes
• choruses

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Whooper swans feed in shal­low bod­ies of water and con­sume aquatic plants and roots. Cygnets feed on small in­sects and other in­ver­te­brates to meet their high pro­tein re­quire­ments for proper growth and de­vel­op­ment. In shal­low fresh wa­ters, whooper swans use their webbed feet to dig in the mud and then dip their head into the water to feed on shal­low roots and tu­bers. Par­ents also help cygnets feed by stir­ring up the water col­umn to make aquatic veg­e­ta­tion more ac­ces­si­ble. Whooper swans can also feed in ter­res­trial habi­tats or near salt­wa­ter tidal en­vi­ron­ments. In fresh­wa­ter sys­tems, their for­ag­ing ac­tiv­ity peaks in the morn­ing and af­ter­noon. Whooper swans that pre­fer feed­ing in salt­wa­ter sys­tems have for­ag­ing peaks dur­ing the time gap be­tween morn­ing and af­ter­noon. Feed­ing is harder dur­ing high tide, so whooper swans pre­fer to rest at high tide and feed dur­ing low tide. Ter­res­trial for­ag­ing be­hav­iors are af­fected by day length, tem­per­a­ture, and safety. When days are short, cold, and dark, whooper swans are less en­er­getic and for­age less in com­par­i­son to days that are longer, warmer, and brighter. In areas with farm­ing, such as Den­mark and north­ern Ger­many, whooper swans feed on crops dur­ing the win­ter. In cen­tral Scot­land, swans that rely on agri­cul­tural land feed on left­over grains in au­tumn and then feed on grass from mid-win­ter until spring. The ma­jor­ity of whooper swans fed on fresh­wa­ter roots, stems, and leaves and the re­main­ing mi­nor­ity feed on mus­sels in shal­low ma­rine wa­ters. (Brazil, 2003)

• Primary Diet
• carnivore
  • piscivore
  • insectivore
• herbivore
  • folivore
  • granivore
  • lignivore
• omnivore

• Animal Foods
• fish
• insects

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts

Pre­da­tion

Rest­ing whooper swans are able to curl up on the ground to re­duce ex­po­sure to cold cli­mates while still main­tain­ing the abil­ity to open their eyes eas­ily to spot preda­tors. Preda­tors often at­tack clutches by steal­ing one egg at a time when par­ents take in­cu­ba­tion breaks to feed. Once whooper swans reach their adult size, the threat of pre­da­tion de­creases, and most pre­da­tion oc­curs when cygnets are young and rely heav­ily on parental pro­tec­tion. Due to their larger size, whooper swans are not very agile on land and often re­treat into the water to be safe from ter­res­trial mam­malian preda­tors. (Brazil, 2003)

• Known Predators

  • arctic foxes (Vulpes lagopus)
  • red foxes (Vulpes vulpes)
  • golden eagles (Aquila chrysaetos)
  • brown bears (Ursus arctos)
  • wolverines (Gulo gulo)
  • coyotes (Canis latrans)
  • raccoons (Procyon lotor)
  • American minks (Neovison vison)
  • North American river otters (Lontra canadensis)
  • snapping turtles (Chelydra serpentina)
  • California gulls (Larus californicus)
  • great horned owls (Bubo virginianus)
  • bobcats (Lynx rufus)
  • white-tailed eagles (Haliaeetus albicilla)
  • common ravens (Corvus corax)
  • hooded crows (Corvus cornix)
  • wild boars (Sus scrofa)

Ecosys­tem Roles

Large quan­ti­ties of bio­mass are lost when whooper swans feed on their pre­ferred sub­merged macro­phyte, fen­nel pondweed; this stim­u­lates the pondweed to grow at in­ter­me­di­ate depths. In con­trast, their less fa­vored plant, clasp­in­gleaf pondweed grows at ei­ther shal­low or deep depths. As such, whooper swans play a key role in im­pact­ing plant com­mu­nity struc­tures. There have also been re­ported cases of nest par­a­sitism by grey­lag geese and red-crested pochard birds that lay their eggs in whooper swan nests. (Brazil, 2003; Kior­boe, 1980; Sand­sten and Klaassen, 2008)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Whooper swans have been hunted in the past but are gen­er­ally un­afraid of hu­mans and will take food di­rectly from a human's hand. This level of ap­proach­a­bil­ity oc­curs mainly dur­ing the win­ter when food is scarce. Their friend­li­ness has drawn crowds of peo­ple and tourists who come to ad­mire their beauty and sig­na­ture whoop­ing calls. (Brazil, 2003)

• Positive Impacts
• food
• ecotourism

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Some whooper swans pre­fer to feed on crop plants due to the higher nu­tri­tional value ob­tained from eat­ing these foods. This ad­versely af­fects the farm­ers whose crops may be dam­aged. In ad­di­tion, the path­o­genic avian in­fluenza virus H5N1 was iso­lated from the eye­lids of a whooper swan dur­ing the 2010 H5N1 out­break in Japan. Whooper swans are sus­cep­ti­ble car­ri­ers of the dis­ease due to their wide ranged mi­gra­tory be­hav­iors. (Brazil, 2003; Bui, et al., 2013)

• Negative Impacts
• injures humans
  • carries human disease
• crop pest

Con­ser­va­tion Sta­tus

Human ac­tiv­i­ties that threaten whooper swans in­clude hunt­ing, egg poach­ing, and habi­tat degra­da­tion. There have been con­ser­va­tion ef­forts to pre­serve pop­u­lar wet­land sites from Ice­land to China and laws that make hunt­ing the swans il­le­gal in Rus­sia. Con­ser­va­tion ef­forts have been fruit­ful, as the sta­tus of the species is con­sid­ered one of “least con­cern.” (Birdlife In­ter­na­tional, 2012; Brazil, 2003)

• IUCN Red List

  Least Concern

• US Migratory Bird Act

  No special status

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

Priscilla Kuo (au­thor), The Col­lege of New Jer­sey, Keith Pecor (ed­i­tor), The Col­lege of New Jer­sey, Leila Si­cil­iano Mar­tina (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

Ref­er­ences

Birdlife In­ter­na­tional, 2012. "IUCN Red List of Threat­ened Species" (On-line). Cygnus cygnus. Ac­cessed Oc­to­ber 25, 2013 at http://​www.​iucnredlist.​org/​details/​22679856/​0.

Black, J. 1996. Part­ner­ships in Birds. Ox­ford: Ox­ford Uni­ver­sity Press.

Brazil, M. 2003. The Whooper Swan. Lon­don: T & AD Poyser.

Bui, V., H. Ogawa, L. Ngo, T. Baatart­sogt, L. Abao, S. Tamaki, K. Saito, Y. Wan­tan­abe, J. Run­stadler, K. Imai. 2013. H5N1 highly path­o­genic avian in­fluenza virus iso­lated from con­junc­tiva of a whooper swan with neu­ro­log­i­cal signs. Archives of Vi­rol­ogy, 158: 451-455.

Dun­ning, J. 1992. CRC Hand­book of Avian Body Masses. Boca Raton: CRC Press.

Gar­dars­son, A., K. Skarphedins­son. 1984. A cen­sus of the Ice­landic whooper swan pop­u­la­tion. Wild­fowl, 35: 27-47.

Kior­boe, T. 1980. Dis­tri­b­u­tion and pro­duc­tion of sub­merged macro­phytes in Tip­per Grund (Ringkob­ing Fjord, Den­mark), and the im­pact of wa­ter­fowl graz­ing. Jour­nal of Ap­plied Ecol­ogy, 17: 675-687.

Laubek, B., L. Nils­son, M. Wie­loch, K. Kof­fi­jberg, C. Sud­feldt, A. Follestad. 1999. Dis­tri­b­u­tion, num­bers and habi­tat choice of the NW Eu­ro­pean whooper swan Cygnus cygnus pop­u­la­tion: re­sults of an in­ter­na­tional cen­sus in Jan­u­ary 1995. Vo­gel­welt, 120: 141-154.

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

Rees, E., O. Einars­son, B. Laubek. 1997. Cygnus cygnus whooper swan. BWP Up­date, 1: 27-35.

Sand­sten, H., M. Klaassen. 2008. Swan for­ag­ing shapes spa­tial dis­tri­b­u­tion of two sub­merged plants, favour­ing the pre­ferred prey species. Oe­colo­gia, 156: 569-576.