I believe the answer you are looking for is Migration. Take birds for example, when it gets cold they go south to where it's warm, and then back again in the summer, they call this migrating. Thus your answer is migration.
Migration is the Correct Answer you would be looking for.
The definition of a migration is a movement to another place, often of a large group of people or animals. An example of migration is geese flying south for the winter.
