God did. It is simple, we are above animals. That is not to say we should treat them in a cruel manner. The question posed is the appropriate one; whether it is cruel or not. Seeing cruel treatment of animals is something you will know when you see it. Animals are in zoos to protect them. If they were not in zoos they would be roaming free and either hunters would be killing them or we would be killing them to protect ourselves. I hope that any sane bird owner would allow there bird some flying time.