The same kind of behavior you may, unfortunately, see in a cage can also easily and perhaps even more commonly occur in the wild. In the wild, there is more risk involved with a newborn litter, and with more inherent risk also comes the natural instinct of the mother to engage in eating her babies instead of allowing another animal to do the same. There is also more of a risk of the mother becoming very hungry in the wild, which will result in her eating her babies in order to gain nutrition to feed the rest of the litter.