When Drinking Bird's head gets wet and he bobs back up, the water on his head starts to evaporate which lowers the temperature of his glass head. The lowered temperature causes some of the red vapor in his head to condense which in turn creates a drop in pressure in his head. The base of Drinking Bird's body is warmer and at a higher pressure so the liquid in the body pushes up toward the head. As the liquid rises, Drinking Bird's head becomes top heavy and he tips over. The bottom end of the neck tube rises above the surface of the liquid in Drinking Bird's body. A bubble of warm vapor rises up the tube through this gap, displacing liquid as it goes. Liquid flows back to the bottom bulb and pressure equalizes. The weight of the liquid in the bottom bulb restores the bird to its vertical position. A thermodynamic cycle is created that keeps Drinking Bird tipping over and over again.