Answer:
No population can grow beyond certain limits. This is called a limiting factor.
Step-by-step explanation:
Let's take the example of rabbits.
In the warmer temperature, the rabbit population grows, and the adults grow older/die a bit.
In colder temperatures, there is less room to support the population, as well as not enough food to support so many rabbits, so some pass away.
Another example of rabbits is mates! If there aren't enough of each genders, then there won't be enough mates to reproduce.
This is why the rabbit/squirrel population is never really expanding/"contracting".
Hope this helps!