如图为桃花的部分结构示意图，请据图回答下列问题

    Winter is very cold in many countries. It's easy for you and me to keep warm. If we are cold, we can just buy a warm coat or use a heater and we will feel better. But what about animals? How do they keep warm in winter?

    Some animals migrate(迁移). This means they travel to places where the weather is warmer. Many birds leave before the winter starts. They fly in groups. If they fly together, the trip will be safer. They like to migrate to the same places every year. Do you know how they can find the same places? Scientists say that birds use the sun, moon and stars to help them. Other animals like moose (麋鹿) also migrate. Fish and whales swim to warmer water.

    Some animals don't have leave their homes. They hibernate in winter. They fall into a very deep sleep. The animals' temperature drops and their breathing slows down. Before the winter, these animals must eat too much food that they get very fat. If they don't eat enough, they may die when they are hibernating.