Who takes care of the animals in the forest?

No one does, the animals have to hunt food and look after themselves.

Most wild animals are born with adaptations to take care of themselves.
Some animals are taken care of by their parents for the few first few days/weeks/months after birth- for example bear cubs, swans and elephants,

while other animals must fend for themselves as soon as they are born, such as snakes. Fortunately many animals are born with defense mechanisms such as claws or venom.