No. Some birds do not migrate at all, but live in the same range all year long. This is especially true in warmer climates, but some birds even stay in the Arctic all year. Some birds that migrate move in other directions, such as east or west, or from higher elevations to lower elevations, to get to where they can find food or shelter in the winter. And or course, in the Southern Hemisphere, most birds fly north in the winter.
No. Only some species are migratory.
When birds fly South for the winter it is called migration.
The main reason that birds fly south in the winter is because they can't stay in a cold place so they fly south to a warmer place during the winter.
Monarch Butterflies. They fly south for the winter like birds do.
migration
Migration
migration
It's warm
They don't stay when it is snowing. Hasn't anybody learned that birds fly south in the winter?
Birds do not fly all the way to the southern hemisphere, they fly to the equator.
Instinct
They fly to find better food supplies (and better weather).