FALSE VAMPIRE BATS: Megadermatidae

PHYSICAL CHARACTERISTICS

False vampire bats are medium-sized to large bats with a head and body length of 2.6 to 5.5 inches (6.5 to 14.0 centimeters). Their wingspans can reach 3 feet (1 meter). The Australian false vampire bat, also called the Australian ghost bat, is among the largest of the microchiropteran (my-kro-keer-OP-ter-an) bats. Microchiroptera is one of the two suborders of bats and includes most of the bats in the world.

False vampire bats have large ears joined by a band of skin across the forehead and noseleafs, which are fleshy protrusions from the nose. The heart-nosed bats have a leaf-like nose that is heart-shaped.

Megadermatids (meg-ah-der-MAT-ids; bats in the family Megadermatide) have a tail that is either short or absent. These bats typically have relatively short and broad wings.

Their fur tends to be long and gray in color, although the yellow-winged bats have bright yellow or orange wings and ears, with bluish fur. False vampire bats have twenty-six or twenty-eight teeth. The flesh-eating, or carnivorous, megadermatids, such as the Australian false vampire bats, have sharp and strong canine teeth for tearing flesh and crushing bones.

GEOGRAPHIC RANGE

Megadermatids are found in Africa, Asia, east India, Philippines, and Australia.

HABITAT

Megadermatids live in open, dry habitats in Australia, and in open woodlands. They also live in the very dry or arid areas of Africa and India. Typical habitats for heart-nosed bats include dry lowlands, coastal strip habitats, and sometimes river valleys.

DIET

Many of the megadermatid species are also known as false vampire bats because people mistakenly believed that they eat blood. Megadermatids eat insects or small vertebrates (animals with backbones), and none of them feed only on blood. The carnivorous species, such as the Australian false vampire bats, eat small vertebrates that include fish, frogs, lizards, birds, mice, or other bats. The Asian false vampire bats have a diverse diet, feeding on everything from insects, spiders, fish, birds, and frogs, to rodents and even occasionally smaller bats. False vampire bats are among the top predators (hunters) of the forest, hunting mainly birds, other bats, and rodents.

Yellow-winged bats eat insects on the ground or while flying. They feed on large and small insects, including moths and butterflies, grasshoppers, beetles, flies, and mosquitoes.

BEHAVIOR AND REPRODUCTION

Megadermatids make echolocation (eck-oh-loh-KAY-shun) calls through the nose. Echolocation is a technique of sending out sounds and then using the reflection or echoes of the sound to detect objects. In bats these sounds are too high-pitched for humans to hear. Megadermatids use their large noseleaf to focus the sound outwards.

Megadermatids roost (settle or rest) in caves, rock crevices, buildings, and trees. Roosting habits vary from solitary to colonial. The Asian false vampire bats roost in caves, buildings, and hollow trees in small groups, although one particularly large colony of nearly 2,000 was reported in India. Eating a wide range of foods from insects to birds, these bats maneuver (mah-NOO-ver) well as they snatch their food.

False vampire bats commonly kill the prey (animals hunted for food) by biting the head and crushing the skull. False vampires share their prey with other members of the family group, consisting of a pair of adults and their non-breeding young. The Australian false vampire bat drops on small mammals from above, and envelops them with its wings before biting the head and neck. They carry their prey to a high point or back to the roost.

Heart-nosed bats hang upside down on a low perch while they scan the area for their meals. This bat eats beetles, centipedes, scorpions, and small bats. From its perch, typically 10 to 16 feet (3 to 5 meters) above ground, this bat twists its body 180°, using its eyes and ears to search for prey. When it spots a meal, the bat swoops down and snatches the prey, carrying it back to its perch. There, the bat removes the legs and wings before eating the body.

Some megadermatids, such as the yellow-winged bats, appear to be monogamous (muh-NAH-guh-mus), meaning that the male and female pair up, which is unusual in bats and mammals. Heart-nosed bats mate in monogamous pairs for the breeding season. They make an effort to keep the same mate during the following breeding seasons. Mated pairs have a breeding site that the male defends. Prior to foraging for their food in the evening, the male of the heart-nosed and false vampire bats sing from perches.

Megadermatids give birth to a single offspring during each breeding period. In yellow-winged bats, following a gestation (pregnancy) of about three months, most births of the single offspring occur in April. False vampire bats also have a gestation period of about three months, and give birth at the beginning of the rainy season. Sometimes, an older member of the family may remain to sit with the young while the adults hunt.

MEGADERMATIDS AND PEOPLE

People are destroying the natural habitat of megadermatids, causing many of these species' populations to decrease.

KEEPING WARM

Ghost bats cannot stand getting cold. Studies suggest that these bats need to keep their body temperatures between 95 and 102.2°F (35 to 39°C). When surrounding temperatures are higher or lower, these bats need to need to increase or decrease their metabolic rate to keep warm or stay cool. They move between a number of caves, depending upon the weather, which means they need multiple cave sites where they can roost. Females especially need to keep warm while they are pregnant.

CONSERVATION STATUS

The IUCN lists the heart-nosed bat as being Near Threatened, not currently threatened, but may become so; and the Australian false vampire bat as Vulnerable, facing a high risk of extinction in the wild.

AUSTRALIAN FALSE VAMPIRE BAT (Macroderma gigas): SPECIES ACCOUNT

Physical characteristics: Australian false vampire bats are among the largest of the bats. They have forearms that range from 3.7 to 4.6 inches (9.6 to 11.8 centimeters) long, and weigh 2.6 to 5 ounces (74 to 144 grams). Their head and body length is 3.9 to 5.1 inches (10 to 13 centimeters). Females are smaller than males.

These bats are also called ghost bats, because their fur is light brown to gray to almost white. In some areas, ghost bats have an ashy gray back and white underparts. These bats have wide ears that meet above the head and are fused. They have large eyes relative to their heads, along with prominent noseleafs.

Geographic range: Australian false vampire bats are found in northern Australia, mainly north Queensland, along the north central coast, and in the northwest.

Habitat: Australian false vampire bats live in both arid regions and rainforest areas, such as north Queensland. They typically roost in caves and abandoned mines.

Diet: The Australian false vampire bat is Australia's only carnivorous bat. These bats eat large insects, such as cockroaches, and vertebrates, such as reptiles, frogs, birds, small mammals, and other bat species.

Behavior and reproduction: Australian false vampire bats commonly hang from a branch and wait for their prey to pass on the ground below. The bats then drop down, envelop the prey with their wings and kill it by biting its head and neck. They also catch prey while in flight. Australian false vampire bats eat large amounts of food and consume much of their prey, including its flesh, bones, teeth, fur, small feathers, and the exoskeletons of insects.

Australian false vampire bats move to the warmer northern Australia area when the weather becomes cooler, and then back to the cooler southern areas when the weather becomes warm. These bats do use echolocation, yet they appear to capture their prey with their extremely sensitive hearing and vision. Their echolocation calls are less than one millisecond long. Australian false vampire bats roost alone or in small groups. During the breeding season, for the most part, females gather in colonies, while males gather into their own colonies. Yet some studies have found that some males are always present with the females. There are typically fewer than 100 bats in a group.

Australian false vampire bats generally mate in April or May and gestate for about three months. The females bear a single offspring. Mothers stay with their young and also fly with them to forage (search) for food during the first several weeks of life. Both sexes reach reproductive maturity at about their second year of life.

Austalian false vampire bats and people: Australian Aborigines, the early inhabitants of Australia, have a spiritual connection to the Austalian false vampire bats. Mining operations are destroying their roosting sites, causing a decline in their population. These bats are also extremely sensitive to any disturbance. People that enter a ghost-bat cave colony may cause the group to become nervous and leave.

Conservation status: Australian false vampire bats have declined in population because people have destroyed their habitats. They are categorized as Vulnerable by the IUCN. ∎

FOR MORE INFORMATION

Books:

Fenton, M. Brock. Bats. New York: Checkmark Press, 2001.

Fenton, M. Brock. The Bat: Wings in the Night Sky. Buffalo, NY: Firefly Books, 1998.

Nowak, Ronald M. "Australian Giant False Vampire Bat, or Ghost Bat." Walker's Mammals of the World 5.1 Online. Baltimore: Johns Hopkins University Press, 1997. http://www.press.jhu.edu/books/walker/chiroptera/chiroptera.megadermatidae.macroderma.html (accessed on July 4, 2004).

Richardson, Phil. Bats. London: Whittet Books, 1985.

Ruff, Sue, and Don E. Wilson. Bats. New York: Benchmark Books, 2001.

Schober, Wilfried, and Eckard Grimmberger. The Bats of Europe and North America. Neptune City, NJ: T.F.H. Publications, Inc., 1997.

Web sites:

"Bat." MSN Encarta Online Encyclopedia 2004.http://encarta.msn.com/encyclopedia_761557637/Bat.html (accessed on July 4, 2004).

French, Barbara. "False Vampires and Other Carnivores." Bat Conservation International, Inc. http://www.batcon.org/batsmag/v15n2-5.html (accessed on July 4, 2004).

Hester, L., and P. Myers. "Family Megadermatidae (False Vampire Bats)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Megadermatidae.html (accessed on July 4, 2004).

"Yellow-winged bat—Lavia frans." American Zoo. http://www.americazoo.com/goto/index/mammals/63.htm (accessed on July 4, 2004).