Answer:
Animals hibernating is the answer
Step-by-step explanation:
Hiberntion is when animals sleep for months in the cold winter
When animals hibernate, it is usually in the winter. They store food with them for when they wake up.
An example is squirrels which store acorns near them when they go to hibernate
Birds migrating is usually to lay eggs
Trees losing leaves is usually so that they can store their precious nutrients like glucose
Insects during metamorphosis is when they change form, eg from a caterpillar to a butterfly