WOW! Thermodynamics & Pressure Differentials! A classic physics demonstration in the shape of a duck.
Set the bird into motion by giving him a drink and dunking his beak into a glass of water. That’s it! He’ll lift his head, then tip over again to dip his beak into the water and get another drink. This thirsty bird continuously bobs as long as it has a glass of water to dunk into.
Instructions on box.