The story of The Ugly Duckling is perhaps the best known story involving swans. It was written by the Danish writer Hans Christian Andersen in 1843 under the title Den grimme ælling. In short, a duckling hatches. His brothers and sisters are normal, but he is ugly and clumsy. He suffers harassment and is eventually driven away. He wanders alone. Miraculously, he survives the winter. He comes to a pond, where he sees swans swimming. Drawn by their beauty, he approaches them, expecting to be driven off. Instead, they welcome him. He joins them and, seeing his reflection in the water, finds out that he is a swan too.
The Wild Swans
Hans Christian Andersen also wrote The Wild Swans, published as De vilde svanerin 1838. A king has 12 children, 11 sons and one daughter. He is a widower, and decides to remarry. The woman he married is a witch, who turns her step-sons in swans. They carry away their sister Elisa, where she is out of the way of their wicked step-mother. Elisa works day and night, knitting nettles into magic shirts. The king finds her, and marries her. She continues her knitting, but is mute and cannot explain to the King what she is doing or why. One night she runs out of nettles, and gathers more in a graveyard. An evil Archbishop sees her and accuses her of witchcraft. The King sentences Elisa to be burned as a witch. At the last moment, her swan brothers descend from the sky and rescue her. They put on the magic shirts and are restored to human form. Elisa regains her voice and explains her actions. The charge against her is dismissed, and she is reunited with her brothers.
The story is based on the Irish story of the The Seven Swan Brothers and the German fairy tale The Six Swans. In the Aarne-Thompson classification system for folktales, there are dozens of European stories in which a woman saves or is saved by her brothers, who have been turned into various types of birds (type 451).