Why do barn owls eat six small mammals a day?

Owls have high metabolisms and so must hunt frequently in order to remain healthy. The main food largely depends on the species of Owl. For example, Scops and Screech Owls feed on insects mostly, while Barn Owls eat mainly mice, shrews and voles. Larger Owls such as the Eagle Owl will prey upon hares, young foxes and birds up to the size of ducks and gamebirds. Some species have specialised in fishing, such as the Asian Fish Owls and African Fishing Owls. Although certain species have these preferences for food type, most owls are opportunistic, and will take whatever prey is available in the area.