Swans are birds of the genus ''Cygnus'' within the family
Anatidae
The Anatidae are the biological family (biology), family of water birds that includes ducks, goose, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted f ...
. The swans' closest relatives include the
geese
A goose (: geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera '' Anser'' (grey geese and white geese) and ''Branta'' (black geese). Some members of the Tadorninae subfamily (e.g., Egyp ...
and
duck
Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...
s. Swans are grouped with the closely related geese in the
subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...
Anserinae
The Anserinae are a subfamily in the waterfowl family Anatidae. It includes the swans and the true Goose, geese. Under alternative systematics, systematical concepts (see e.g., Terres & NAS, 1991), it is split into two subfamilies, the Anserina ...
where they form the
tribe
The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...
Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae. They are the largest
waterfowl
Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...
and are often among the largest
flighted birds in their range.
There are six living and many
extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
species of swan; in addition, there is a species known as the
coscoroba swan which is no longer considered one of the true swans. Swans usually
mate for life, although separation sometimes occurs, particularly following nesting failure, and if a mate dies, the remaining swan will take up with another. The number of
eggs in each
clutch
A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does th ...
ranges from three to eight.
Taxonomy and terminology
The genus ''Cygnus'' was introduced in 1764 by the French naturalist
François Alexandre Pierre de Garsault
François Alexandre Pierre de Garsault was a French people, French botanist, zoologist and painter. de Garsault was born on 16 April 1691 in Aix-en-Provence, France and died 3 August 1778 in Paris, France. de Garsault was a member of the French ...
. The English word ''swan'', akin to the German , Dutch and Swedish , is derived from the
Indo-European root '(''H'') ().
are known as ''cygnets'', from
Old French
Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th or (diminutive suffix ''et'' ), from the
or (diminutive suffix ''et'' ), from the Latin word , a variant form of , itself from the Greek language">Greek
Greek may refer to:
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group
*Greek language, a branch of the Indo-European language family
**Proto-Greek language, the assumed last common ancestor of all kno ...
, a word of the same meaning. An adult male is a ''cob'', from Middle English (leader of a group); an adult female is a ''pen''.
A group of swans is called a bevy or a wedge.
and are among the largest flying birds. The largest living species, including the
, can reach a length of over and weigh over . Their wingspans can be over .
Compared to the closely related geese, they are much larger and have proportionally larger feet and necks.
Adults also have a patch of unfeathered skin between the eyes and bill. The sexes are alike in
, but males are generally bigger and heavier than females.