Cave explorers in western Mexico are well acquainted with the vampire bat, Desmodus rotundus. Grupo Zotz, the western branch of the Mexican Society for Underground Exploration (SMES), has explored hundreds of caves in the area and reports that approximately 90% of them house at least one colony of vampires.
Vampires Prey on Domestic Animals
“Their numbers are on the rise,” stated Zotz co-founder Susana Ibarra, “while the populations of beneficial bats are in drastic decline, mainly due to the widespread use of insecticides. Before the arrival of the conquistadores, Desmodus rotundus mainly fed on wild mammals, such as deer and opossum.
Then cattle, horses, goats and pigs were brought onto the scene. Vampire bats suddenly had the equivalent of a banquet spread before them on a nightly basis and their population began to increase dramatically, throwing nature’s delicate balance out of kilter.
The presence of vampire bats in a cave can be detected from a distance, due to the peculiar pungent odor of their guano, which is a black semi-liquid, the end product of their diet of blood.
When disturbed, vampire bats tend to scurry around cave walls like crabs, rather than fly away, as do most other species. They are also capable of taking flight from the ground. Their ability to creep like tarantulas, hop like frogs or run like rodents makes them highly successful at biting the feet or ankles of their prey and disappearing in a hurry.
Bite of the Vampire
Contrary to popular belief, vampire bats do not suck blood. Instead, they make a small incision with their razor-sharp upper front teeth. This is so well done that human victims report feeling absolutely nothing when the bite occurs. The bat then laps up blood from the wound which is only one to five millimeters deep.
A vampire bat usually takes a maximum of 30 milliliters (one ounce) from its victim. A continuous flow of blood is assured because the bat’s saliva contains an anticoagulant.
In itself, the bite of a vampire bat is not harmful to its host, unless infection sets in. However, in Mexico, as opposed to some other countries like Panama, Desmodus rotundus frequently carries rabies, resulting in the death of significant numbers of livestock.
War against Bats
Desmodus rotundus is found throughout Latin America, from northwestern Mexico to Uruguay. In all these countries, misguided attempts have been made to control vampire populations by exterminating bats of all kinds, including the highly beneficial ones which eat harmful insects or which pollinate a wide variety of plants, from bananas to tequila agaves.
To kill a relatively small number of vampires, ranchers may set fires in caves or seal their entrances, destroying huge populations of beneficial bats or denying them a home.
The Mexican government has a vampire control program which is supposed to impact Desmodus rotundus without harming other bats. Its success, however, depends on functionaries traveling to remote areas on bad roads, catching vampires in nets, painting their backs with a deadly agent and releasing them. “We haven’t seen much evidence that this is working,” reports a Zotz representative.
The first written accounts of blood-eating bats were made in 1498 when Columbus landed in Trinidad. When these descriptions reached Europe, people were reminded of their own legends and the name of a mythical creature was applied to a real animal. Since then, the vampire bat’s history has been a resounding success story.
Sources: Grupo Zotz, Guadalajara, Mexico; Vampire Bats by Laurence Pringle, William Morrow and Company, NY 1982.
