While the word vampire bat brings to mind images of Dracula and other horror-film characters, the truth is that nature has some real-life examples of vampirism. The best known is the vampire bat. There are three species of vampires that survive exclusively on blood: Common Vampire Bats, White-winged Vampire Bats, and Hairy-legged Vampire. While quite different to each other, all three species are native to the American continent.
Vampire bats feed on small mammals or birds, depending on the species. They hunt only at night and target sleeping animals. Vampire bats fly about by emitting ultrasonic sound pulses and using an infrared sensor to find their way. This allows them to fly in full dark and approach their prey without being detected.
Vampire bats seem to dislike human blood, as only a few cases of attack are reported every year. In contrast, vampire bats can cause serious problems in areas where cattle and horses roam outside at night. While the feeding itself doesn't hurt the animal, vampire bats are known to carry the rabies virus, which can be transferred to animals and then, in turn, to people.
To feed, vampire bats bite through the animals' skin, causing a wound not bigger than 5mm (0.2 inches). Using their tongue, the bats then lap in the blood. Special active ingredients in their saliva help prevent the blood from coagulating, while promoting easy flood. Each time they feed, vampire bats take about two tablespoons of blood from their prey, which is enough to maintain their small inch-long bodies.
Because of their unique digestive system, vampire bats must feed at least once every 48 hours to survive. Blood is usually digested quickly and lost through urine, so it's important that they replace it constantly. After feeding, vampire bats usually return to their shelters, where they sleep until the next night.
Besides being incredible flying machines, vampire bats can also walk, run, and jump with great agility. This is a great asset when stalking prey, and a great way to move around their colonies, which sometimes consists of over 2000 bats. Despite their bad reputation, vampire bats are rather harmless to humans, and can become tamed, especially when living near large human populations.