Rain Powered Mobile

This is not a rain guage. The object as I envision it should not look like it was designed to collect water. It might have a human or animal or other form. One characteristic of the form should be that it have a recognizable front and back. Placed in a public place the object would be immobile most of the time. When rain falls on the object it would be collected and used to cause the object to move. The movement could be to turn on a central point or to cause it to roll or walk in a circle. In the course of a year (even in Seattle) the object would make less than one rotation or roll or walk only a foot or two. I think such an object of imagination and ingenuity could find general public acceptance. One of the problems with such a rain engine would be to design it to be tolerant of pigeon droppings and leaves.