Whistle while you work being happy makes the job more enjoyable. A little bird told me. On the page where the work committee is gathered discussing the problem, a bird is sitting in the window listening. This is one of the reasons the chickens like him so much. The books list different kinds of songs that he sings.
Folk songs are ones that have been handed down from one generation to the next.
Folk music was not written down, but learned by rote. Most of the songs have unknown authors. They often tell a bit of history or culture. Down, Old Joe Clark, Swanee River. Shalom Chaverim and Henei Ma Tov speak of unity and peace.