One night, a boy called Dòu Dīng er was sound asleep. Suddenly in the middle of the night, he work because he heard a mysterious voice singing. He looked around the house for clues, but couldn’t find what was making the noise. It wasn’t his dog, cat, chicks, or even pigs. He finally found the “unknown singers” outside on the lawn. The boy took the “unknown singers back inside the and found out that these singers make sounds with their wings, not their mouth. Can you guess who the “unknown singers” were?