Why does a chinchilla always bite the cage?

A chinchilla biting the cage is usually to draw the owner’s attention, a way to express a need. For example, when it wants food or out-of-cage time, this behavior may appear.

If the owner forgets to feed it, the chinchilla may bite the cage or call to show displeasure and get attention. So when it bites the cage, check for unmet needs.