Question

migration is another word for necessity explain the reference why birds migrate​

Answer 1

Answer:

Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. ... It occurs mainly in the northern hemisphere, where birds are funneled on to specific routes by natural barriers such as the Mediterranean Sea or the Caribbean Sea.

Answer 2

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Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding and wintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting by humans, and is driven primarily by availability of food.