Common Vampire Bat

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 an anticoagulant in their saliva preventing the blood from clotting (9). Vampire bats live in large colonies 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 females 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). A common vampire bat lives up to 12 years in the wild (2).

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 education programmes, such as a video programme developed by Bat Conservation International in the United States, and a range of other local and national educational and training efforts. 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. Additionally, it has been suggested that more targeted, non-chemical methods for the control of these bats are developed, which do not needlessly harm other species (1). 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.

No species has contributed more to the misunderstanding and fear of bats than the vampire bat (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, 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 thumb help the bat to climb around on its prey and to take off after feeding (5) (7). The coat is dark greyish-brown, paler on the stomach and females are usually larger than males (2).

Found in arid and humid parts of the tropics and subtropics, occupying rainforests as well as deserts, making its home in caves, mines, tree hollows and occasionally abandoned buildings (1) (8) (9).

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).

Classified as Lower Risk/least concern (LR/lc) on the IUCN Red List 2004 (1).

The common vampire bat is one of the few bat species that are considered an agricultural pest, due to its feeding on livestock and spreading of diseases, which has resulted in 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 programmes, particularly in ranching areas, with control methods including burning, gassing and dynamiting of potential roosts (1) (10). Fortunately, the common vampire bat is not considered threatened, but vampire bat control programmes have nevertheless had a considerable impact (1), especially on other helpful, fruit-eating bats that are destroyed by people who mistake them for vampires (10). One control programme in Venezuela reportedly destroyed 40,000 caves, resulting in the loss of large populations of harmless bats as well as other cave fauna (1).