Swans are birds of the genus Cygnus within the family Anatidae. The swans' closest relatives include geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae, forming the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae. They are the largest waterfowl and are often among the largest flighted birds in their range. There are six living and many extinct 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 ranges from three to eight.

Closest relatives