The Orff-Schulwerk Volume 1s, in whatever language they were adapted, often begin with "Cuckoo, where are you?"
When Googling the German lyrics, "Kuckuck, Eierschluck," an opera by the composer Englebert Humperdinck (the German Composer, not the pop star!) comes up.
At this time, I don't think I know enough German to fully research this piece.