Animals do many different, amazing things to get through the winter. Some of them migrate .Many birds migrate in autumn. Because the trip can be dangerous, some travel in large groups. For example, geese   fly in noisy, "V"-shaped groups. Other kinds of birds fly alone. Some animals stay active in winter. They must change themselves as weather changes. For example, a kind of rabbits grow white fur   to help them hide in the snow. It's hard to find food in winter for animals. Some animals, like mice, collect lots of food in autumn. Some animals eat different kinds of food as the seasons change. The red fox eats fruit and insects in spring, summer and autumn. In winter, it cannot find these things, so it eats small animals instead.  Some animals hibernate  for part or all of the winter. This is a special, very deep sleep. The animal uses very little energy. In autumn, these animals get ready for winter by eating much more food than in summer and storing it as body fat. Squirrels store food like nuts to eat later in winter. Bears and some bats hibernate.  Cold-blooded animals like fish, frogs and snakes have no way to keep warm during the winter.  Snakes find protection in holes, and spend the winter without moving during the whole season. Many birds travel in large groups because   _  .
they can easily find food this way there is danger everywhere they can get warm at night they will not feel lonely