This is how a dipping bird toy/ drinking bird dunking bird works explained. Explained with animations. A drinking bird works by cooling of the head via. evaporative cooling. That will cause the liquid (dichlormethane) inside the glass construction to condense. According to the ideal gas law, that will cause a pressure difference, sucking up all dichlormethane. This causes the center of mass to change, and when the torque is no longer in equilibrium the bird will rotate. A smart valve at the bottom will cause the fluid to fall back when a tube is above the water level. Also known as Bobbing bird, bird drinking water toy, rocking bird