If your mother wants to tell you something, she uses words. Birds cannot talk as we do. But some birds can make sounds to warn their young of danger. They have their own way to make the young birds do certain things.
The jackdaw is a kind of blackbirds that lives in Europe. Jackdaws live together in flocks（群）.Young jackdaws do not know their enemies. When an older jackdaw sees a dog, it makes a loud rattling sound. The younger birds know this sound means an enemy is nearby. The sound warns them to know their enemies.
If a young jackdaw is in a dangerous place, a jackdaw parent flies over him from behind. The parent bird flies low over the young bird’s back. The parent’s tail feathers（羽毛） move quickly from side to side. It is trying to say,“Follow me.” At the same time, the parent calls out,“Key-aw,” The parent means,“Fly home with me.” The young bird then follows the older one home. Young jackdaws do not have to learn what certain sounds mean. They know the meaning of these sounds form the time they hatch（孵出）