Oak leaves are generally not a suitable food source for most animals due to:
* Tannins: Oak leaves contain high levels of tannins, which are compounds that can be toxic to many animals.
* Low nutritional value: Oak leaves are relatively low in protein and other essential nutrients compared to other plant matter.
Some animals might occasionally consume oak leaves, but they are not a primary food source for any known species.
Perhaps you're thinking of a different type of animal or a different type of food?