Swan maiden

The "swan maiden" (German: Schwanjungfrau) is a tale classified as ATU 400, "The Swan Maiden" or "The Man on a Quest for His Lost Wife," in which a man makes a pact with, or marries, a supernatural female being who later departs. The wife shapeshifts from human to bird form with the use of a feathered cloak (or otherwise turns into a beast by donning animal skin). The discussion is sometimes limited to cases in which the wife is specifically a swan, a goose, or at least some other kind of bird, as in Enzyklopädie des Märchens.

The key to the transformation is usually a swan skin, or a garment with swan feathers attached.

In the typical story a maiden is (usually bathing) in some body of water, a man furtively steals, hides, or burns her feather garment (motif K 1335, D 361.1), which prevents her from flying away (or swimming away, etc.), forcing her to become his wife. She is often one of several maidens present (often celestial beings), and often it is the youngest who gets captured. The bird wife eventually leaves this husband in many cases.

The oldest narrative example of this type is Chinese, recorded in the Sou shen ji ("In Search of the Supernatural", 4th century), etc.

There are many analogues around the world, notably the Völundarkviða and Grimms' Fairy Tales KHM 193 "The Drummer". There are also many parallels involving creatures other than swans.