Conditions of the environment play an important role in the survival of the population in a certain area or location.
Since the temperature or the weather of the environment changes according to the season so living organism try to adapt according to their ability.
Some organisms adapt to the changing environment and thus can survive.
But certain organisms that can not adapt in such condition they migrate from such environment to other favorable environments.
Those organisms that can not adapt in such an environment and can not migrate for a favorable environment can easily be extincted and thus can not save their existence.