This is an easy to make bird water whistle.The bottle needs to be filled half with water. When someone blow air in, the air bubbles change the shape and size of air chamber inside the bottle thus resonance frequency get changed and multi frequency sounds are created.
To make it you need a juice straw, a small price of plastic strip , hot glue , a small plastic bottle ( Like an eye drop or ear drop medicine bottle) and fabric color. Follow the below video instruction to make it.
Step 1: Video Instruction
Here is the video instruction to help you understand better. (click)
Make your own whistle and enjoy.