Nature regulates itself

Clever mechanics regulating themselves do not only exist in technical devices, but also in nature:

Rabbits are known for their fast and numerous reproduction, for example in parks of cities where they can find enough food and do not have any natural enemies. But in nature the population of rabbits is balanced: There are not too many and not too few of them. This is due to the existence of natural enemies such as foxes.

Rabbits are hunted and killed by foxes. They are prey to foxes. This connection between rabbits and foxes is called a predator-prey relationship. Foxes live on finding rabbits for prey. Therefore, when there are many rabbits, there can be many foxes, too: They find enough food and are able to reproduce.

If the population of foxes increases, there is an effect on the population of rabbits.