Migration is a type of movement that changes population size.
Population viability population sizes are under constant fluctuation.
Migration is a type of movement that causes a population to fluctuate.
What can happen to a population when animals begin to migrate?

1: It expands
2: harm them
3: it can change species
4: Move to another area
5: it can eat more
6: it can go extinct
7: it can fluctuate
8: Plant growth is reduced