The same way it helps a human.. They Get refreshed!
It's because of hibernation.
because of the hibernation
Terns migrate, they do not hibernate, Birds cannot hibernate.
Some of them do. Not most of them. Most of them fly away with there babies to a warmer location.
The same way it helps any animal that hibernates - it protects if from the extreme cold of winter.
When bears go to sleep in the winter, it is called Hibernation. Squirrels, birds, and other animals who dislike the cold do the same thing.
Nightingales normally come out of hibernation in the spring after spending the winter in southern Africa. The nightingale is traditionally thought to announce the coming spring time.
Note that most birds do not hibernate, although it does happen with penguins. Hibernation is by definition a period of inactivity; any hibernating animal does not eat.
There are many animals besides bears that go into hibernation every year. Some species of bat hibernate as do hedgehog, squirrel, dormice and even some birds.
a scarecrow think sometime
A bird sanctuary protects birds from all types of predators and the birds can't starve because the people always feeds them.
After hibernation, chipmunks go to find love, then get ready for next hibernation.