American Leaf-Nosed Bats: Phyllostomidae

Physical characteristics: Vampire bats have a combined head and body length of about 2.7 to 3.7 inches (6.8 to 9.3 centimeters). One of these bats' striking features is their pointed front teeth. These bats have dark grayish brown fur, which is lighter on the underside. Ears are pointy and there is no visible tail. The thumb is clawed. Females are generally larger than males.

Geographic range: Vampire bats are found in northern Mexico to central Chile, Argentina, Uruguay, and Trinidad.

Vampire bats do feed on animal blood—usually livestock, such as pigs or cows. (M. W. Larson/Bruce Coleman Inc. Reproduced by permission.)

Habitat: Vampire bats live in warm climates, in both tropical and subtropical (nearly tropical, with warm temperatures and little rainfall) areas. They are commonly found where there is plenty of livestock. These bats are found roosting in caves, mines, tree hollows, and occasionally abandoned buildings.

Diet: Vampire bats feed on blood. These bats need about 2 tablespoons (29.6 milliliters) of blood each day; this is about 60 percent of the bat's body weight. Bats need to feed nightly.

Behavior and reproduction: Vampire bats are social animals; they roost in colonies that can range from twenty to 100 individuals. Much larger colonies of thousands have also been found.

Vampire bats approach their intended food source stealthily. They can walk, run, and hop along the ground, using their strong hind limbs and thumbs. At night, when vampire bats emerge to hunt for food, their victims are often sleeping. The bat will land beside the sleeping animal and then climb up until it finds a feeding spot. With its sharp front incisor teeth, the bat pierces the animal's skin and laps up blood from the wound. Vampire bats have chemicals in their saliva that stops blood from clotting. The bite rarely wakes a sleeping victim.

These bats occasionally will share the blood with other bats from its colony. After one female grooms another, the female being groomed may regurgitate (re-GER-jih-tate; throw up) part of her blood meal for the grooming female. It is also common to see females regurgitate food for their offspring.

Vampire bats mate year round. Females typically give birth to one offspring in April to May, or October to November. The offspring remain with their mothers for several months after they are weaned. They often share blood from the same wounds with their mothers.

Vampire bats and people: The fact that these bats feed on blood, combined with mythological stories about vampires, has caused many people to fear all bats. While the fears are largely myths, vampire bats can transmit rabies to humans and animals. These bats have caused tens of millions of dollars of damage to livestock farmers by transmitting rabies. They are considered pests in many livestock areas where they live. Also, researchers are investigating the anti-clotting properties of these bats' saliva to help with people who have strokes, in which a blood clot in the bloodstream cuts off blood supply to a part of the brain.

Conservation status: In areas with lots of livestock, vampire bats flourish. These are not considered threatened animals. ∎