C. Birds moving south when the weather gets colder
Explanation:
The seasonal changes are the changes, which occurs in accordance with the changes in the season. The seasonal migration in birds is a good example of seasonal changes, in this, the birds move from one place to another to stay away from harsh weather and come back again when the weather is suitable.
Other changes in the given questions are terminal changes and lead to the damage to ecosystem. These changes are not the seasonal one.
Answer: C. Birds moving south when the weather gets colder
Seasonal change is the change in season due to change in abiotic factors like weather conditions, sunlight availability, wind direction etc. Seasons change from summer to winter, winter to summer, summer to spring etc. These seasonal changes affect the life of biological communities including plants and animals. Some organisms adapt to changing seasonal conditions but others completely avoid them by migrating to other places where weather conditions are suitable for their survival. Therefore, birds moving south when the weather gets colder is because of seasonal change as birds cannot tolerate cold weather conditions.
