Write a short note on migration in animals?

Explanation

Migration is a two way movement of the whole population from and to an area so as to avoid unfavourable conditions. Migration is quite common in birds of colder countries, e.g., Wagtails, Siberian Crane, seal. Many of them visit India during winter. Reinder, Fur Seal are mammals of cold countries which shift to warmer places during winter months. A migration from fresh water to sea and back is called catadromous. Salmon does the reverse migration called anadromous.