Desmodus rotundus

The common vampire bat (Desmodus rotundus) is a small, leaf-nosed bat native to the Americas. It is one of three extant species of vampire bat, the other two being the hairy-legged and the white-winged vampire bats. The common vampire bat mainly feeds on the blood of livestock, approaching its prey at night while they are sleeping. It uses its razor-sharp teeth to cut open the skin of its hosts and laps up their blood with its long tongue. The species is highly polygynous, and dominant adult males defend groups of females. It is one of the most social of bat species with a number of cooperative behaviors such as social grooming and food sharing. Because it feeds on livestock and is a carrier of rabies, the common vampire bat is considered a pest. Its conservation status is categorized as Least Concern by the International Union for Conservation of Nature (IUCN) because of 'its wide distribution, presumed large population tolerance of a degree of habitat modification, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.' The common vampire bat was first described as Phyllostoma rotundum by Étienne Geoffroy Saint-Hilaire in 1810. Another description was published in 1826 as a new species Desmodus rufus by Maximilian Wied, in the second volume of his work detailing his explorations in Brazil, erecting a new genus Desmodus.The species received several scientific names before being given its current one—Desmodus rotundus—by Oldfield Thomas in 1901. It is classified under the subfamily Desmodontinae along with two other species: the hairy-legged vampire bat (Diphylla ecaudata), and the white-winged vampire bat (Diaemus youngi). These three species compose the 'true' vampire bats, as opposed to the 'false' vampires of the family Megadermatidae and the spectral bat. All three species of Desmodontinae specialize in feeding on the blood of warm-blooded animals. However, the common vampire bat feeds on mammalian blood more than the other two species, which primarily feed on that of birds. The three species resemble each other, but the common vampire bat can be distinguished by its longer thumb. It is the only extant member of its genus, although other fossil species have been described. It has a haploid number of 14, for a karyotype of 28 chromosomes. A description published under the name Desmodus puntajudensi (Cuban vampire bat) by Woloszyn and Mayo in 1974 was later recognised as a synonymous with this species. The common vampire bat is short-haired, with silver-gray fur on its undersides, demarcated from the darker fur on its back. It has a deeply grooved lower lip, and a flat, leaf-shaped nose. A well-developed, clawed thumb on each wing is used to climb onto prey and to assist the animal in take-off. The bat averages about 9 cm (3.5 in) long with a wingspan of 18 cm (7 in). It commonly weighs about 25–40 grams (2 oz), but its weight can drastically increase after a single feeding. The braincase is relatively large, but the snout is reduced to accommodate large incisors and canines. It has the fewest teeth among bats. The upper incisors lack enamel, which keeps them razor-sharp. Its dental formula is 1.1.2.01.1.3.0, for a total of 18 teeth. While most other bats have almost completely lost the ability to maneuver on land, vampire bats are an exception. They can run using a unique, bounding gait in which the forelimbs are used instead of the hindlimbs to propel forward, as the wings are much more powerful than the legs. This ability likely evolved independently within the bat lineage. Three pads under the thumb function like a sole. It is also capable of leaping in various directions, heights, and distances. When making a jump, the bat pushes up with its pectoral limbs. The hindlimbs keep the body over the pectoral limbs which are stabilized by the thumbs. Common vampire bats have good eyesight. They are able to distinguish different optical patterns and may use vision for long-range orientation. These bats also have well-developed senses of smell and hearing: the cochlea is highly sensitive to low-frequency acoustics, and the nasal passages are relatively large. They emit echolocation signals orally, and thus fly with their mouths open for navigation. They can identify a metal strip 1 centimetre (0.39 in) wide at a distance of 50 centimetres (20 in), which is moderate compared to other bats. The common vampire bat is found in parts of Mexico, Central America, and South America. They can be found as far north as 280 kilometres (170 mi) south of the Mexico–United States border. Fossils of this species have been found in Florida and states bordering Mexico. The common vampire is the most common bat species in southeastern Brazil. The southern extent of its range is Uruguay, northern Argentina, and central Chile. In the West Indies, the bat is only found on Trinidad. It prefers warm and humid climates, and uses tropical and subtropical woodlands and open grasslands for foraging. Bats roost in trees, caves, abandoned buildings, old wells, and mines. Vampire bats will roost with about 45 other bat species, and tend to be the most dominant at roosting sites. They occupy the darkest and highest places in the roosts; when they leave, other bat species move in to take over these vacated spots.