SUMMARY: Desmodontinae (Vampire Bats)
Common Name
: vampire
Taxonomy: Three genera, Desmodus, Diaemus, and Diphylla, each containing one species
Distribution: Ocean coasts of Mexico, Central & South America
Fossil Record:
Size Range: Head and body length range from 63 - 93 mm forearm from 50 - 63 mm.
Until recently, vampire bats were classified as family Demondontidae. However, based on recent immunological, morphological, and chromosomal data, they have been reclassified as a subfamily of Phyllostomidae.

There is no external tail, and the tail membrane is short. Unlike other Phyllostomids the nose lacks a true nose leaf, which have been modified into hair-less pads, with U-shaped grooves at the tip. The ears are rather small.

The incisors and canines are specialized for cutting, sicklelike, with their cutting edge forming a V. The cheek teeth are greatly reduced, with all crushing surfaces absent.
Desmodus has 20 teeth, Diaemus 22, and Diphylla has 26 teeth. All the long bones of the wing and leg are deeply grooved for the accommodation of muscle.

Subfamily Desmodontinae are the true vampire bats, believed to feed exclusively on fresh blood. Domestic cattle, chicken, and turkey are commonly fed upon.
Diaemus and Diphylla both appear to feed upon birds typically, with the latter also feeding on small mammals. Desmodus is the only serious threat, feeding on livestock, sometimes humans and other mammals.

Vampires are very agile, they walk rapidly with feet and thumbs on both horizontal, or vertical surfaces. Their method of feeding is to alight on or near a victim, and climb or walk onto it. They attack areas where hair is scant, or without hair or feathers. The bats make a quick shallow bite with the modified incisors, cutting the skin. The bite usually does not disturb the victim. The saliva of vampire’s contains an anti-coagulate which can keep the wound open for up to 8 hours. The tongue is used like a capillary tube, the tongue is protruded and retracted to and from the wound continuously, creating a flow of blood.

Desmodus can sometimes consume so much blood, they can barely fly, and sometimes crawl to protected places to wait for digestion to occur. The kidney is specialized for rapid digestion, by eliminating most of the water which makes up a large percentage of blood volume.

Vampire bats seem to prefer to roost in almost complete darkness, sheltering in caves, old wells, mine shafts and tunnels, hollow trees and buildings. Aggregations range from solitary roosts to colonies of thousands. The bat tend not to leave their roosts until after dark.

(from the books "Bats - A Natural History" and from "Walker's Bats of the World")