How do you make a whistle out of elderberry branch?

To make a whistle from an elderberry branch, first select a straight, young branch with a diameter of about half an inch. Cut a piece approximately 6-8 inches long and remove the bark from one end. Then, use a knife to create a small notch or slit about an inch from the end, which will serve as the mouthpiece. Finally, blow into the notch while covering the other end with your finger to produce a whistle sound.