This migration is usually accompanied by a more or less complete metamorphosis.
The result of migration is that races of widely different origin and habit have had to adapt themselves to similar conditions.
In North America there is no such barrier: the Miocene flora has been able to escape by migration the fluctuations of climate and to return when they ameliorated.
Further development was, however, not stopped, but in many cases stimulated by migration and settlement in new homes.
After oil was found in an uninhabited region, there was a migration to that area.
During the famine, there was a largemigration of people to a region with fertile land.
The forcedmigrationof the displaced people from their home country was unethical and tragic.
The birds are currently beginning their large migration to the south.