The goop in his butt is methylene chloride has a very low boiling point, and therefore evaporates quickly. At room temperature, one or two degrees temperature difference causes the bright red chemical to climb to his head. Suddenly topheavy, he falls over. The felt head, soaked in the water from the cup, cools the methylene chloride, and it drains back to the bottom. The bird rights itself, and it starts all over again.Is this perpetual motion? Technically yes, but it’s not energy for free! Temperature differentials drive the motor. That energy comes from the environment - from the sun. Is it efficient? Hardly, but it's still very cool.China supplier:Email : fangzhengcn@hotmail.com Skype ID : chanceller819