The Battle of the Birds is a Scottish fairy tale collected by John Francis Campbell in his Popular Tales of the West Highlands. He recorded it in 1859 from a fisherman near Inverary, John Mackenzie and was, at the time, building dykes on the Ardkinglas estate. Joseph Jacobs took it from there for his Celtic Fairy Tales and added some additional elements.
Illustration by Arthur Rackham, from The Allies Fairy Book from 1916. The king's son asks the giant for his youngest daughter's hand in marriage.
The youngest son is a stock character in fairy tales, where he features as the hero. He is usually the third son, but sometimes there are more brothers, and sometimes he has only one; usually, they have no sisters.
The youngest son hero of The Boy Who Had an Eating Match with a Troll confronts the troll. (Illustration by Theodor Kittelsen)
Illustration by Warwick Goble to Beauty and the Beast: the heroine is the youngest daughter in her family.
The heroine of Diamonds and Toads is the younger of two sisters.