Common Vampire Bat
(Desmodus rotundus)
Habitat
Common vampire bats live in subtropical and tropical regions, and inhabit humid tropical forests to arid desert habitats. They live at elevations of up to about 7,500 feet (2,288 m). These bats roost in secluded, nearly dark areas such as caves with fissures, tree hollows, abandoned wells and buildings, and deep mine shafts.
Physical Characteristics
Females are a bit larger than males, but otherwise both sexes are nearly identical in appearance. Brown, gray, or brownish-red fur covers their body; it is lighter on the underside. They have large eyes, large pointed ears and no tail. Their nose appears compressed and has two large nostrils. Their sense of smell is acute. The mouth has very sharp canine and incisor teeth.
Common vampire bats weight between 0.5-1.8 ounces (14-51 g). Average head and body length is approximately 2.7-3.5 inches (7-9 cm), the size of an adult human’s thumb. Wing span averages 8 inches (20.3 cm). The thumb on each wing is well developed. Unlike most bats, the legs of the common vampire bat are very strong, enabling this bat to easily crawl, hop and jump.
Life Span
Life span in the wild is up to 9 years; in captivity about 20 years
Diet
In the wild: The common vampire bat feeds on the blood of mammals, and sometimes domesticated birds. Host animals might be cattle, horses or pigs. Wild animals are also a valuable blood source, and humans have sporadically supplied a tasty blood meal.
Reproduction
Common vampire bats sexually mature at about 9 months of age, and mate throughout the year. When the male finds a receptive female, he climbs upon her back. Then he holds her wings with his, and grabs the back of her neck with his mouth. Gestation lasts about 7 months, after which a single young is born; twins occasionally occur. The mother suckles her young for the first month, after which the young also receives regurgitated blood meals from the mother. Young develop quickly, accompanying their mother on hunts by 4 months of age. Young are fully grown by 5 months and are fully weaned by 10 months of age.
Life Cycle
Common vampire bats are social animals. They roost alone, in small groups, or in colonies of up to 2,000 bats. When colonies are larger than about 50 bats, they split up into smaller groups consisting of females and their young. A single male often roosts close to each female group and attempts to maintain his right to breed with the females of the group. Clashes between males frequently occur; they are hard-fought battles that involve biting, kicking and battering with wings.
Social Bonds are enhanced by grooming, this normally occurs between females and young, and female to female. A female grooms another female for several minutes, after which the recipient regurgitates part of their blood meal for the other to consume. This practice proves important since one in three bats are unsuccessful in finding a blood meal each night. A vampire bat dies if it does not get a blood meal in two to three days. One strategy for survival is to groom or beg from another bat, in order to receive a much needed blood meal.
Dinner on the Hoof
Flying about 3 feet (0.9 m) off the ground, the bat’s sharp sense of smell and echolocation find a “victim”. Echolocation happens when the bat sends ultra-high frequency sounds through its nose. The sounds reflect off objects in their surroundings, bouncing back to the bat’s sensitive ears. The bat determines the distance to its target by how long it takes the sounds to return. This bat is lucky—there’s a sleeping cow right ahead!
So as not to alert the cow, the bat lands on the ground and easily crawls or hops to its snoozing dinner using their thumbs, forearms and wings. It lightly climbs onto the cow and uses heat sensors in its nose to find where blood is near the skin’s surface. The bat licks the site clean with its tongue and then trims the cow’s hair with its teeth. It then painlessly cuts through the skin and injects saliva containing a chemical to prevent blood clots. The bat then laps oozing blood with its tongue. The bat soon becomes engorged with blood and is too heavy to fly away. It crawls off the cow and moves along the ground to a safe place while digestion lightens its heavy load.
Location at the Zoo
Vampire bats are no longer exhibited at Woodland Park Zoo.
Conservation Connection
Vampire bat populations are healthy throughout their range. In many Latin countries, however, government-sponsored programs attempt to eradicate vampire bats. Over the last several decades, cattle ranches spread throughout Mexico, Central and South America. Vampire bat populations soared and their range expanded, as cattle are easy targets. Unfortunately, vampire bats can transmit rabies and other diseases to cattle. Annually, over 100,000 cattle die from the bites of vampire bats, and ranchers lose millions of dollars in revenue. During these eradication programs, people kill other harmless bat species mistaken for vampire bats. Additionally, many species of bats are in trouble due to destruction of their habitat and roosting sites.
All bats have an enormous ecological significance. Insect-eating bats consume huge quantities of flying insects — a single bat may consume 500 mosquitoes in an hour. Nectar-feeding bats are important pollinators. Fruit-eating bats disperse seeds over great distances in tropical forests, ensuring food supplies for other forest inhabitants.
How You Can Help!
The effort to save bats and other animals requires cooperation and support at the regional, national and international levels. You can help in this cause. Join and become active in a conservation organization of your choice. Tell your elected representatives on the national, state and local levels about the importance of preserving wild habitats and endangered species.
Contact Woodland Park Zoo at webkeeper@zoo.org about supporting conservation programs at the zoo. Learn other ways you can help conserve wildlife and habitats by visiting our How You Can Help page.
Sources and Suggested Reading
Nowak, Ronald M. 1994. Walker’s Bats of the World. The Johns Hopkins University Press, Baltimore, MD. 287 p.
For Kids!
Horowitz, Ruth. 1991. Bat Time. Four Winds Press,
New York, NY.
Milton, Joyce. 1994. Bats and Other Animals of the Night. Random House, New York, NY. 32 p.
Taxonomic classification varies between references. Classification information used in this fact sheet was taken from Mammal Species of the World: A Taxonomic and Geographic Reference; Don E. Wilson and DeeAnn M. Reeder, Second Edition, 1993.