What Do Vampire Bats Eat? The Surprising Truth About Their Diet

The vampire bat is one of the scariest pop-icons in the animal kingdom, although most of the fear is due to their diet and not their actual behavior. Vampire bats are small members of the bat family, consisting of three distinct species: the common vampire bat (Desmodus rotundus), the white-winged vampire bat (Diaemus youngi), and the hairy-legged vampire bat (Diphylla ecaudata). Although these bats are generally harmless, they are well-known for their exclusive diet of blood, which is why they are called “vampire” bats.

While the moniker may be scary, these animals typically do not bother humans. Understanding these fascinating animals also comes with an appreciation for the evolution of their unique diet. Read on to learn more about what vampire bats eat.

What Do Vampire Bats Eat?

Vampire bats can be found from northern Mexico through Central America and South America, as well as some islands in the West Indies. Only a single bat has ever been found in the U.S. One hairy-legged bat was collected in an abandoned railroad tunnel in Texas in 1967.

Vampire bats are sanguivores, feeding exclusively on blood. The three species of bats are the only mammals on the earth that feed only on blood. Although pop-fiction movies and literature make it seem as if vampire bats feed on humans, it rarely happens in the real world.

Vampire bats primarily feed on domestic livestock, such as cows, pigs, horses, goats, and even chickens, mainly because these animals are abundant. The common vampire bat is opportunistic, but it typically prefers mammals. Its diet also varies by location. Common prey in the rainforest includes tapirs, deer, peccaries, cattle, monkeys, and birds. The white-winged vampire bat and the hairy-legged vampire bat prefer birds.

Foods Vampire Bats Eat

While vampire bats don’t eat like other mammals, they do consume the blood of the following animals:

• cows and other cattle
• pigs
• horses
• goats
• chickens
• tapirs
• deer
• peccaries
• monkeys
• other small wild mammals
• wild birds
• humans (rarely)

How Do Vampire Bats Hunt and Feed?

Vampire bats have some of the most unique and interesting feeding strategies in the animal kingdom. A hungry bat finds a potential host using thermoception, usually in complete darkness. They only come out at night and hunt when their hosts are usually asleep. This makes it less likely they will be caught. Vampire bats generally land on the ground and climb up their hosts.

Once they are close, they use a heat-sensitive nose to locate warm spots on the skin and shear away hair with their premolars. When the skin is exposed, they use razor-sharp incisor teeth to make a cut about 0.20 inches deep. Their upper teeth lack enamel to ensure they stay as sharp as possible. Museum handlers have reportedly cut themselves simply by handling vampire bat skulls.

Once the skin has been cut, their saliva has enzymatic compounds that slow clotting and slightly numb the area. With the cut numbed and freely bleeding, the bat then places its channeled tongue under the cut and laps up the blood. In a single sitting, a vampire bat can drink 20 grams of blood or about half its body weight. Due to a rapid digestive system, the bat can quickly urinate excess fluid and take off.

How Did Vampire Bats Evolve to Drink Blood?

Vampire bats are in a family known as “New World leaf-nosed bats.” Within this family are bats that feed on nectar, pollen, fruit, meat, insects, and blood. Vampire bats evolved within this family, although hematophagy is rare in the animal kingdom because it is biologically challenging. Mammals need adaptations to overcome iron poisoning, excess protein, and excess liquid to evolve into sanguivores.

There are several theories that explain how vampire bats became specialized in hematophagy. Recent research points towards their ancestors being insect eaters. It’s possible that the ancient ancestors of vampire bats originally fed on insects that themselves fed on the wounds of large animals. Over time, they slowly adapted to feed on the animals themselves. Another potential theory is that the earliest bats fed on other ectoparasites (ticks, fleas, and lice) and developed the ability to tolerate blood through their prey.

Regardless of how they evolved, it’s clear that all three species of vampire bats in the subfamily Desmodontinae are closely related and share a common ancestor. It’s also likely that the first vampire bats split from their family and formed a distinct genus within 4 million years, setting a potential record for one of the fastest examples of mammalian natural selection.

Are Vampire Bats Dangerous to Humans?

While humans are large mammals with plenty of blood, we generally don’t need to worry about vampire bats drinking it. If you live in Central or South America and sleep outside, it’s possible that a vampire bat could decide to feed on you. Researchers in Brazil’s Catimbau National Park have found traces of human blood in the feces of hairy-legged bats. However, as domestic animals and people generally live in close proximity in that area, scientists believe bats are exhibiting opportunism.

If a bite does occur, the person is rarely aware of it until the next morning, when only a small cut is visible. Vampire bats can carry rabies, although it is typically spread by feeding on domestic livestock. Humans can also contract rabies from vampire bat bites, but cases are rare. The best protection is thoroughly cleaning bat-related wounds immediately and seeking urgent medical attention. Post-exposure vaccination is highly effective when administered promptly after exposure.