Common vampire bat (Desmodus rotundus)
|Also known as:||vampire bat|
|Size||Length: 7 - 9 cm (2)|
Wingspan: 35 - 40 cm (2)
|Weight||30 - 40 g (3)|
- Believe it or not a bite from a common vampire bat is unlikely to hurt because their teeth are so sharp.
- The saliva of common vampire bat contains several anticoagulants that prolong blood flow.
- Smaller groups of female common vampire bats have demonstrated an altruistic blood-sharing system where individuals that did not successfully feed gain a regurgitated meal from those that did.
- Surprisingly, the common vampire bat has the fewest teeth of all the bat species.
The common vampire bat is classified as Least Concern (LC) on the IUCN Red List (1).
No species has contributed more to the misunderstanding and fear of bats than the common vampire bat (Desmodus rotundus) (4). Public perception and movie portrayal of them as huge, creepy, blood-sucking killers is sensationalist and incorrect. The common vampire bat in fact rarely kills its prey and is relatively small and ordinary looking, although it does possess some fascinating adaptations to its specialized feeding behaviour (5). The thin, broad, pointed, blade-like incisors are so sharp that the victim seldom notices the incision into its flesh (6). Heat sensors on their nose are also an adaptation to help the vampire bat find a good spot on an animal’s body to feed (5). Strong hind legs and a special, elongated and robust thumb help the bat to climb around on its prey and to take off after feeding (5) (7). The coat is dark greyish-brown to reddish to golden, paler on the stomach and females are usually slightly larger than males (2).
The common vampire bat ranges from northern Mexico through Central and South America to central Chile in the west and Uruguay in the east (1).
Found in arid and humid parts of the tropics and subtropics, the common vampire bat occupies rainforests as well as deserts, making its home in caves, mines, tree hollows and occasionally abandoned buildings (1) (8).
Much of the behavior exhibited by common vampire bats revolves around their feeding habits of drinking blood from birds and mammals, preferentially livestock due to their abundance (2) (7). A common vampire bat finds its prey with echolocation, smell, sound, and possibly heat; it then uses special heat sensors in its nose to find veins that are close to the skin (3). These bats do not actually suck blood from their host, but rather make a small incision and lap up the blood (8), with a product in their saliva which turns clotted blood back into liquid blood (9). Vampire bats live in colonies typically of 30 to 150 bats, with larger numbers rare, in which there are groupings of 8 to 12 females that roost close together on a regular basis, and single males roosting separately, defending territories (2) (3). Within these smaller female groups individuals exhibit a rare example amongst animals of reciprocal altruism, involving a remarkable blood-sharing behaviour in which well-fed bats regurgitate blood to hungry companions (3). Individuals are not always successful in hunting, and hungry bats may starve to death within three days (4). Studies indicate that common vampire bats will regurgitate to related and unrelated bats within the group, demonstrating a mutual ‘buddy system’, with pairs of bats forming tight blood-sharing relationships (3). Associations between females are maintained over many years (2), and partner fidelity appears to be central to the persistence of this amazing reciprocal-exchange system (4).
Common vampire bats mate year round, with birth peaks during April and May and in October and November (7). Most females have one pregnancy per year, although more than one is possible (2), and single offspring are usual (7). The gestation period is about seven months (2), and pups are born with their eyes open (7). The mother nurses the pup for the first two months (7), introducing regurgitated blood meals to them during their second month, and at four months the pup leaves the nest to accompany its mother on hunts (2). The common vampire bat lives up to 12 years in the wild (2).
The common vampire bat is one of the few bat species that are considered an agricultural pest, due to its feeding on livestock and potential for spreading of diseases, which has resulted in paralytic rabies outbreaks in cattle (1) (10). Recent incidents of vampire bats attacking humans in Peru, Brazil and El Salvador have also attracted world-wide press interest, compounding the species’ already negative and misunderstood public perception (1). The result has been wide-scale eradication programs, particularly in ranching areas, with control methods including treating them with anticoagulants (the only treatment sanctioned by local governments), burning, gassing and dynamiting of potential roosts (1) (10). Fortunately, the common vampire bat is not considered threatened, but misguided, misapplied vampire bat control programs have nevertheless had a considerable impact (1), especially on other helpful, fruit- or insect-eating bats that are destroyed by people who mistake them for vampires (10). One control program in Venezuela reportedly destroyed 40,000 caves, resulting in the loss of large populations of harmless, beneficial bats as well as other cave fauna (1).
The management and conservation of vampire bats was discussed in depth at the 11th International Bat Research Conference held in Brazil in August 1998, attended by bat researchers and public health and veterinary officers. Conservation initiatives so far have included the need to synchronise vampire bat management and control programs with bat conservation needs and programs. A video programme developed by Bat Conservation International in the United States focuses on how to solve the vampire bat problem, and how to conserve other bat species (9). The development of immunisation techniques has also been advocated as a potential conservation action for the future, involving oral vaccinations for the localised control of rabies in vampire bats. The current control protocol used from Argentina to Mexico uses chemical methods for the control of common vampire bats, and does not needlessly harm other species (1) (9). Although the problems common vampire bats cause certainly need to be addressed, it is important that work is also done to dispel the animal’s undeserving negative reputation, since such unfounded prejudice could unfairly influence the treatment of this fascinating, unique and highly specialised species.
Authenticated (25/02/11) by Dr Rodrigo Medellin, Co-Chair of the IUCN Bat Specialist Group,
- Anticoagulant: substance that prevents the clotting of blood.
- Echolocation: method of detecting objects by reflected sound. Used for orientation and detecting and locating prey by bats and cetacea (whales and dolphins).
- Gestation: the state of being pregnant; the period from conception to birth.
- Incisors: the front or cutting teeth.
- Reciprocal altruism: an apparently altruistic behaviour that is actually of mutual benefit, performed with the understanding that the recipient will reciprocate at some future date.
IUCN Red List (June, 2009)
Animal Diversity Web (January, 2006)
- Altringham, J.D. (1996) Bats: Biology and Behaviour. Oxford University Press, Oxford.
- Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
Nationalgeographic.com (January, 2006)
- Burnie, D. (2001) Animal. Dorling Kindersley, London.
Blue Planet Biomes (January, 2006)
San Francisco State University (January, 2006)
The Wild Ones Animal Index (January, 2006)
- Medellin, R. (March, 2011) Pers. comm.