Wounds and the origin of blood-feeding in bats

This new theory about the origin of blood-feeding in bats is based on four main premises: (1) that the diets and feeding behaviour of some bats have always varied; (2) that the Miocene mammal fauna of South America included many large (≥ 2 kg body mass) forms; (3) that wounds offered protovampaire bats the opportunity to feed on blood; and (4) that sharp, strong upper incisor teeth were a prerequisite to feeding at wounds. This theory proposes that variation in feeding behaviour led protovampire bats to feed on concentrations of insect larvae at wounds on large mammals, thence to insects and body fluids, and finally to blood. The chiropteran family Phyllostomidae is confined to the New World and its members frequently have robust upper incisor teeth and flexible foraging behaviour. Elsewhere in the world, bats with flexible foraging behaviour lack robust incisors, while those with robust incisors are more conservative in their foraging. The wound theory of the origin of blood-feeding in bats takes into account their anatomy and foraging behaviour as well as the availability of large prey. In contrast to earlier theories that blood-feeding in bats originated from fruit-eaters with robust incisors or through the gleaning of ectoparasites, the wound theory also explains why vampire bats occur only in the New World.