After a while the boy began to move about as the others did, but all three of the children at times did unusual things. They would stand under the trees and move their arms and legs and heads about in a way which was neither walking nor running nor sitting down. They went through these movements at intervals every day and the robin was never able to explain to his mate what they were doing or trying to do. He could only say that he was sure that the Eggs would never flap about in such a manner; but as the boy who could speak robin so fluently was doing the thing with them, birds could be quite sure that the actions were not of a dangerous nature. Of course neither the robin nor his mate had ever heard of the champion wrestler, Bob Haworth, and his exercises for making the muscles stand out like lumps. Robins are not like human beings; their muscles are always exercised from the first and so they develop themselves in a natural manner. If you have to fly about to find every meal you eat, your muscles do not become atrophied (atrophied means wasted away through want of use).