Why is there a wide variety of animals in forests?

Because the forest is a comfortable habitat for many species of animals. A forest is a huge ecosystem in which animals can find a home – burrows, dens, hollows, etc., which is protected from the wind and is relatively warm in it even in winter.
There you can also find food in the form of mushrooms, plants, berries, etc. In addition, swamps can often be found in forests, which are sources of fresh water.