Well the play 'The Blue Bird' comes from prior to the great Depression - written in 1908 - or was that just the English version? I found the following about the play, but wonder - did the popular mythology about Blue Birds exist prior to the paly, or stem from it? (Maurice Maeterlinck won the Nobel Prize for literature in 1911)

The Blue Bird

A play for children by Maurice Maeterlinck, published as L'Oiseau bleu in 1908. In a fairy-tale-like setting, Tyltyl and Mytyl, the son and daughter of a poor woodcutter, are sent out by the Fairy Bérylune to search the world for the Blue Bird of Happiness.

The children visit the Land of Memory, the Palace of Night, and the Kingdom of the Future (where they meet the soul of their as yet unborn little brother, who will not survive). The children have a magic diamond that enables them to communicate with inanimate objects and animals. Only when Tyltyl and Mytyl return home do they discover that the Blue Bird has been in their bird cage all along. Tyltyl gives the bird to a neighbor child who has been ill; the bird flies away. True happiness, the children learn, is usually found close to home. It comes from making the journey, not from reaching the destination; from seeking and not from finding; and from acting unselfishly, without thought of reward.

Allie