The bird call has three holes, all easily covered by your fingers while you hold the mouthpiece against your lips. Begin with three loud whistles, lower the tone, and create a falling trill. You can both perform the maneuver when you inhale and when you blow.
See video below.
Delivered in handmade wooden box.
Video: French Francois Morel shows here how the bird sound is produced. Francois Morel is an ornithologist and has been producing bird calls since 1975. Read more about the production of bird whistles.