The common vampire bat (''Desmodus rotundus'') is a small, leaf-nosed bat native to the

Americas The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

. It is one of three extant species of

vampire bat Vampire bats, members of the subfamily Desmodontinae, are Phyllostomidae, leaf-nosed bats currently found in Central and South America. Their food source is the blood of other animals, a dietary trait called hematophagy. Three extant bat species ...

s, the other two being the hairy-legged and the

white-winged vampire bat The white-winged vampire bat (''Diaemus youngi''), a species of vampire bat, is the only member of the genus ''Diaemus''. They are found from Mexico to northern Argentina and are present on the islands of Trinidad and Margarita Island. Etymology ...

s. The common vampire bat practices

hematophagy Hematophagy (sometimes spelled haematophagy or hematophagia) is the practice by certain animals of feeding on blood (from the Greek words αἷμα ' "blood" and φαγεῖν ' "to eat"). Since blood is a fluid tissue rich in nutritious ...

, mainly feeding on the blood of

livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...

. The bat usually approaches its prey at night while they are sleeping. It then uses its razor-sharp teeth to cut open the skin of its hosts and lap up their blood with its long tongue. The species is highly

polygynous Polygyny () is a form of polygamy entailing the marriage of a man to several women. The term polygyny is from Neoclassical Greek πολυγυνία (); . Incidence Polygyny is more widespread in Africa than in any other continent. Some scholar ...

, 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 Rabies is a viral disease that causes encephalitis in humans and other mammals. It was historically referred to as hydrophobia ("fear of water") because its victims panic when offered liquids to drink. Early symptoms can include fever and abn ...

, the common vampire bat is considered a pest. Its conservation status is categorized as

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

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."

Taxonomy

The common vampire bat was first described as ''Phyllostoma rotundum'' by

Étienne Geoffroy Saint-Hilaire Étienne Geoffroy Saint-Hilaire (; 15 April 177219 June 1844) was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theorie ...

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''.Wilson, Don E. and Reeder, DeeAnn M. (editors). (2005). ''Mammal Species of the World. A Taxonomic and Geographic Reference'' (3rd ed), Johns Hopkins University Press. The species received several scientific names before being given its current one—''Desmodus rotundus''—by

Oldfield Thomas Michael Rogers Oldfield Thomas (21 February 1858 – 16 June 1929) was a British zoologist. Career Thomas worked at the Natural History Museum, London, Natural History Museum on mammals, describing about 2,000 new species and subspecies for ...

in 1901. It is classified under the subfamily Desmodontinae along with two other species: the hairy-legged vampire bat (''Diphylla ecaudata''), and the

(''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

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s. The three species resemble each other, but the common vampire bat can be distinguished by its longer thumb. It is the only

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

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 recognized as synonymous with this species.

Physical description

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 In human anatomy, the neurocranium, also known as the braincase, brainpan, brain-pan, or brainbox, is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calv ...

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 Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

is , 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.video
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 The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus (cochlea), modiolus. A core component of the cochlea is the organ of Cort ...

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 wide at a distance of , which is moderate compared to other bats.

Range and habitat

The common vampire bat is found in parts of Mexico, Central America, and South America, as well as the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

islands of

Margarita A margarita is a cocktail consisting of tequila, triple sec, and lime juice. Some margarita recipes include simple syrup as well and are often served with salt on the rim of the glass. Margaritas can be served either shaken with ice (on the rock ...

and

Trinidad Trinidad is the larger, more populous island of the Republic of Trinidad and Tobago, the country. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is the southernmost island in ...

. They can be found as far north as south of the

Mexico–United States border The international border separating Mexico and the United States extends from the Pacific Ocean in the west to the Gulf of Mexico in the east. The border traverses a variety of terrains, ranging from urban areas to deserts. It is the List of ...

. 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.

Behavior

Feeding

The common vampire bat feeds primarily on mammalian blood, particularly that of livestock such as

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

and

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

s. Vampire bats feed on wild prey like the

tapir Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a Suidae, pig, with a short, prehensile nose trunk (proboscis). Tapirs inhabit jungle and forest regions of South America, South and Centr ...

, but seem to prefer domesticated animals, and favor horses over cattle when given the choice. Female animals, particularly those in

estrus The estrous cycle (, originally ) is a set of recurring physiological changes induced by reproductive hormones in females of mammalian subclass Theria. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phas ...

, are more often targeted than males. This could be because of the

hormone A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...

s. Vampire bats hunt at night, using echolocation and olfaction to track down prey.Wilkinson, J. (2001) "Bat Blood Donors", pp. 766-767 in ''The Encyclopedia of Mammals. Facts on File''. Eds. D. MacDonald & S. Norris. They feed in a distance of from their roosts.Nowak, R. M. (1991) ''Walker's Mammals of the World''. pp. 1629. Johns Hopkins Press. When a bat selects a target, it lands on it, or jumps up onto it from the ground, usually targeting the rump, flank, or neck of its prey; heat sensors in the nose help it to detect blood vessels near the surface of the skin. It pierces the animal's skin with its teeth, biting away a small flap, and laps up the blood with its tongue, which has lateral grooves adapted to this purpose. The blood is kept from clotting by an

anticoagulant An anticoagulant, commonly known as a blood thinner, is a chemical substance that prevents or reduces the coagulation of blood, prolonging the clotting time. Some occur naturally in blood-eating animals, such as leeches and mosquitoes, which ...

in the saliva. They are protective of their host and will fend off other bats while feeding. It is uncommon for two or more bats to feed on the same host, with the exception of mothers and their offspring.

Mating and reproduction

Male vampire bats guard roosting sites that attract females, but females often switch roosts. During estrus, a female releases one egg. Mating usually lasts three to four minutes; the male bat mounts the female from the posterior end, grasps her back with his teeth, holds down her folded wings, and inseminates her. Vampire bats are reproductively active year-round, although the number of conceptions and births peak in the rainy season. Females give birth to one offspring per pregnancy, following a gestation period of about seven months. The young are raised primarily by the females. Mothers leave their young to hunt, and call their young to feed upon returning. The young accompany their mothers to hunt at six months, but are not fully weaned until nine months. Female offspring usually remain in their natal groups into adulthood, unless their mothers die or move. The occasional movements of unrelated females between groups leads to the formation of multiple matrilines within groups. Male offspring tend to live in their natal groups until they are one to two years old, sometimes being forced out by the resident adult males.

Cooperation

Regurgitated food sharing in common vampire bats has been studied in both the lab and field, and is predicted by kinship, association, and reciprocal help In a field study conducted in Costa Rica from 1978 to 1983, vampire bats frequently switched between several roost trees and co-roosted with kin and non-kin. Mean genetic kinship within roosting groups was low (r = 0.03 − 0.11), but 95% of food sharing observed in the wild occurred between close kin (first cousins or higher). Most observed food sharing (70%) was mothers feeding their pups. The non-maternal sharing events were kin-biased suggesting that vampire bats prefer to help relatives. However, non-maternal food sharing is even better explained by frequency of interaction, even after controlling for kinship. Food sharing was only observed when the co-roosting association was greater than 60%. Food sharing appears to require social bonds that require development over long periods of time. Among familiar bats, the amount of food given from bat A to bat B is best predicted by the amount of food given from bat B to A. Reciprocal sharing is most obvious over longer time spans as found in primate cooperation. Vampire bats also participate in mutual grooming; two bats groom each other simultaneously to clean one another, and to strengthen social bonds. Bats that groom one another also share food. It was suggested that while grooming, a bat might assess the size of its partner's abdomen to determine if it really needs to eat.

Relationship with humans

The highest occurrence of

in vampire bats occurs in the large populations found in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. The danger is not so much to the human population, but rather to

. Joseph Lennox Pawan, a government

bacteriologist A bacteriologist is a microbiologist, or similarly trained professional, in bacteriology— a subdivision of microbiology that studies bacteria, typically Pathogenic bacteria, pathogenic ones. Bacteriologists are interested in studying and learnin ...

, found the first infected vampire bat in March 1932. He soon proved various species of bat, including the common vampire bat, are capable of transmitting rabies for an extended period of time without artificial infection or external symptoms.Joseph Lennox Pawan
, Caribbean Council for Science and Technology. Retrieved 1 April 2011 Fruit bats of the genus ''

Artibeus The Neotropical fruit bats (''Artibeus'') are a genus of bats within the subfamily Stenodermatinae. The genus consists of 12 species, which are native to Central America, Central and South America, as well as the Caribbean. Description These bat ...

'' were later shown to demonstrate the same abilities. During this asymptomatic stage, the bats continue to behave normally and breed. At first, Pawan's finding that bats transmitted rabies to people and animals were thought fantastic and were ridiculed. Although most bats do not have rabies, those that do may be clumsy, disoriented, and unable to fly, which makes them more likely to come into contact with humans. There is evidence that it is possible for the rabies virus to infect a host purely through

airborne transmission Airborne transmission or aerosol transmission is transmission of an infectious disease through small particles suspended in the air. Infectious diseases capable of airborne transmission include many of considerable importance both in human a ...

, without direct physical contact of the victim with the bat. Although one should not have an unreasonable fear of bats, one should avoid handling them or having them in one's living space, as with any wild animal. Medical attention should be given to any person who awakens to discover a vampire bat in their sleeping quarters. It is possible that young children may not fully awaken due to the presence of a bat (or its bite). The unique properties of the vampire bats' saliva have found some positive use in medicine. A genetically engineered drug called

desmoteplase Desmoteplase is a novel, highly fibrin-specific "clot-busting" (Thrombolysis, thrombolytic) drug development, drug in development that reached Phases of clinical research#Phase III, phase III clinical trials. The Denmark, Danish pharmaceutical co ...

, which uses the

properties of the

saliva Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...

of ''Desmodus rotundus'', has been shown to increase blood flow in

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

patients.

References

External links

Socialbat.org – a blog about vampire bats

ARKive – images and movies of the Common Vampire Bat ''(Desmodus rotundus)''

{{Authority control Desmodus Bats of Central America Bats of North America Bats of South America Bats of Brazil Bats of Mexico Mammals of the Caribbean Mammals of Chile Mammals of Colombia Mammals of Argentina Mammals of Peru Mammals of Bolivia Mammals of Trinidad and Tobago Mammals of Guyana Mammals described in 1810 Vampire bats