Why do animals migrate?

Animal migration is an adaptive behavior to the periodic changes of environmental factors. Seasonal climate change is the main reason for animal migration. Due to climate change, food shortages often occur, which forces animals to migrate to other food-rich areas.

The migration of animals is regular and directional, mostly in large groups. The migration of birds occurs periodically between the breeding area and the wintering area every year, mostly between the northern and southern hemispheres and a few between the eastern and western hemispheres. Moreover, the migration of mammals is huge, such as the great migration of reindeer across the snow.