Use this demonstration to teach:
Physical Science - Temperature/Pressure relationship in gases; evaporation
Physics - Poiseuille equation; Thermodynamics
Biology - Transpiration of water in a plant
The bird is made of a very thin glass. The abdomen of the bird is a bulb filled with a colored fluid (methylene chloride). Fused into this bulb of fluid is a tube that extends up to the bird's head which is another bulb. The structure of the head is similar to the abdomen. Covering the head is a fuzzy material. To drink the body pivots on a "hip joint" that is connected to large legs and feet atop a base that stabilize the bird. The hat and tail feather are there for decoration.
Drinking Happy Bird Hand Boiler - works using the same principles
Begin by dipping the bird's beak into a cup of water. As the water evaporates from the beak the head of the bird is cooler and has lower pressure. Since there is higher pressure in the abdomen of the bird the higher pressure causes the liquid in the abdomen to be forced up the tube toward the head. As more fluid moves into the head the bird's center of gravity changes and the bird tips into the cup of water. Now the gases equalize in the head and abdomen and the fluid also moves back into the abdomen. The bird moves to an upright position once the fluid is back in the abdomen.
Video of the equipment in operation