OLD WORLD FRUIT BATS: Pteropodidae

PHYSICAL CHARACTERISTICS

Bats are broken into two categories: the Microchiroptera (micro-keer-OP-ter-ah) and the Megachiroptera (mega-keer-OPter-ah). The vast majority of bats fall under the microchiropterans, which are in general smaller than the megachiropterans. Pteropodidae is the only family in the megachiropteran category. Pteropodids are commonly referred to as Old World fruit bats. The Old World refers to southern Europe, Asia, and Africa, while New World refers to North and South America.

Old World fruit bats have a wide range in size. Pygmy fruit bats are one of the smallest Old World fruit bats, with a head and body length of 2.4 to 2.8 inches (6 to 7 centimeters), smaller than many microchiropterans. Gigantic flying foxes are 15.7 inches (40 centimeters) long and can have a wingspan of 59 inches (150 centimeters).

In general, Old World fruit bats have large eyes that face forward. These bats have claws on the first finger, their thumb, and most also have claws on their second finger. Their faces are typically doglike, with simple and relatively small ears. Their wings are typically broad and mostly furless. The tail is usually short or absent. With so many different species, fur color varies greatly. Most species of the Old World fruit bat are reddish brown, gray, or black. The underside of the bat is usually a pale color, such as a white or yellow.

Teeth are shaped to bite through fruit skin and crush the soft fruit matter. The front incisors, chisel-shaped teeth at the front of the mouth, are small and all have canines, four pointed teeth. Teeth at the sides and back tend to be flat and wide. In some species, especially those that eat nectar, the tongue is long and can stick out far beyond the end of the mouth.

GEOGRAPHIC RANGE

Old World fruit bats can be found in tropical and subtropical regions of Africa, through southern and central Asia to Australia, including the Philippines, a number of islands of the Indian and Pacific Oceans, in Pakistan, and across India.

HABITAT

Old World fruit bats live in a variety of habitats. Many fruit bats live in humid forests in tropical and subtropical areas. Species of flying foxes live in tropical coastal areas.

DIET

As their name suggests, Old World fruit bats eat fruit along with nectar. Some species eat primarily nectar and pollen, powdery grains that contain the male reproductive cells of seed plants. Other bats also add leaves and flower parts to their diet.

BEHAVIOR AND REPRODUCTION

Like all bats, Old World fruit bats are crepuscular (kri-PUS-kyuh-lur), active at dawn and dusk, or nocturnal, active at night. During the day they roost, settle or rest, by hanging from their feet. They may hang with their wings wrapped around their bodies. If it is hot, they may use their wings to fan themselves. Many of the species roost in extremely large groups, called camps. A bat camp may contain anywhere from ten individual bats to over one million. The larger species often roost in large groups, whereas the smaller species tend to be more solitary. Most roost in trees; others roost in caves, deserted mines, or buildings.

When fruit is not available fruit bats will travel to another area. The larger species are slow and powerful fliers. Some of these bats will fly as far as 30 miles (15 kilometers) to reach a new feeding area. Island bats may fly over to a neighboring island.

Old World fruit bats differ from other families of bats in that most use smell and sight, rather than echolocation (eck-oh-loh-KAY-shun), to navigate and find their food. Echolocation is the technique of emitting sounds than detecting the location of objects from the echoes. Rousette bats are the only Old World fruit bats that use echolocation.

After these bats find their food they typically take it to away to a nearby tree. Smaller species are able to eat while hovering. Large Old World fruit bats, such as many of the flying fox species, may have to land or grab hold of a branch in order to eat the fruits. These bats hang upside down by one foot and use the other foot to hold the food. They bite off chunks of the food, swallow the juice, and spit out the pulp and seeds. Occasionally they also eat the pulp.

Within camps of flying foxes, one male fruit bat usually lives with up to eight female bats. This arrangement is called a harem (HARE-um). Females will produce one young per year. In other species the females may mate with two or more males while the males will mate with as many females as possible. At least one species is considered monogamous (muh-NAH-guh-mus), having one mate. Gestation, or pregnancy, is between four and six months.

OLD WORLD FRUIT BATS AND PEOPLE

Because Old World fruit bats spit out seeds as they eat, they are important for spreading seeds for many plant species that people eat, and use for medicine and materials. Fruits that depend on bats for pollination, the transfer of pollen, or seed dispersal include bananas, peaches, dates, avocadoes, mangoes, and cashews. The species that thrive on nectar are also important pollinators. As these bats lap up nectar with their tongues, pollen sticks to their fur and is then rubbed or dropped when the bat visits its next flower. These bats are an important disperser of many rainforest species, which the planet and people depend upon.

DEADLY DELICACY?

The diet of flying fox bats may have helped solve a medical mystery. Researchers have been trying to understand why the Chamorro people of Guam developed neurological, brain, disorders at 50 to 100 times the rates elsewhere. A 2003 study linked this disease to the popular delicacy of the flying fox bat. These bats eat cycad (SYE-kad) seeds, which come from palm-like cycad plants common on Guam and surrounding Pacific islands. Cycad seeds contain chemicals that are poisonous to the human nervous system. Researchers continue to investigate the connection.

Deforestation, clearing the forest, has caused a decline in the population of many Old World fruit bat species as they lose their habitats and food supply. Forests also protect bats from natural storms, such as cyclones. People consider many of these bats pests, as they can destroy crops, and may try to eliminate them. Other people hunt and eat some of the Old World fruit bats, especially the larger ones. People such as the Chamorro of Guam consider flying foxes a delicacy.

CONSERVATION STATUS

Many of the Old World fruit bat species are facing a serious decline in population, extinction (dying out), and the threat of extinction. Eight species are listed as extinct by the World Conservation Union (IUCN). Thirteen species are listed as Critically Endangered, facing an extremely high risk of extinction in the wild; six species are listed as Endangered, facing a very high risk of extinction; and thirty-six species are listed as Vulnerable, facing a high risk of extinction in the wild.

MARIANAS FRUIT BAT (Pteropus mariannus): SPECIES ACCOUNTS

Physical characteristics: Marianas fruit bats are one of the many species commonly called flying foxes. They are medium-sized bats with a body length of 7.5 to 9.9 inches (19 to 25 centimeters). The males are slightly larger than the females. The abdomen and wings are dark brown to black with silver hairs mixed throughout the fur. Around the neck and sides of the neck are yellow to bright gold on most animals. In some bats, this area is pale gold or pale brown. The color of the head varies from brown to dark brown.

Geographic range: The Marianas fruit bats are found in the Mariana Islands, located in the western Pacific Ocean, 1,500 miles (2,400 kilometers) southeast of Japan. They are also found in Guam, Okinawa, and the Ryuku Islands.

Habitat: Marianas fruit bats live in tropical and subtropical areas. They typically live near a body of water.

Diet: These bats feed primarily on fruit, but they do eat other parts of plant materials, such as the flowers and leaves. Favored foods include the fruits of breadfruit, papaya, and figs, along with the flowers of kapok (KAY-pock), coconut, and gaogao.

Behavior and reproduction: Little is known about the nightly movements and behavior of Marianas fruit bats. Many of these bats live in large colonies that can reach 800 individuals. A smaller portion of these bats roost in smaller colonies of ten to twelve; all-male colonies of ten to fifteen; and some roost independently. During the day these bats primarily sleep. Bats gradually leave the colonies for several hours after sunset to forage, search for food. These bats move from island to island but overall, they do not move about much.

Within larger colonies, some males form harems of several females. The males will defend the females in its group.

Marianas fruit bats and people: Marianas fruit bats are hunted for food and, occasionally, their fur. This is one reason these bats have declined in population. These bats are a delicacy to the native Chamorro culture and are illegally hunted. Habitat destruction is another reason for the decline in population. The introduced species, a species brought from another part of the world, the brown tree snake in Guam has been a major predator on these young fruit bats.

Conservation status: Marianas fruit bats are listed as Endangered by the IUCN. In the Commonwealth of the Northern Mariana Islands (CNMI), the Marianas fruit bat is locally listed as an endangered species due to the decline in population. Under local law it is illegal to hunt the fruit bat anywhere in the CNMI. ∎

INDIAN FLYING FOX (Pteropus giganteus): SPECIES ACCOUNTS

Physical characteristics: Named for its physical similarity to a fox, the Indian flying fox has reddish brown fur and the shape of its head is similar to a fox. These bats are one of the largest of all bats and have a wingspan of more than 4 feet (1.2 meters). Its head and body length ranges from 8 to 12 inches (20 to 30 centimeters). These bats have prominent claws that they use to move through trees and branches.

Geographic range: Indian flying foxes are found throughout Bangladesh, Myanmar, India, Pakistan, and Sri Lanka.

Habitat: The Indian flying fox lives in tropical forests and swamps, where there is a large body of water nearby.

Diet: Indian flying foxes feed almost exclusively on a variety of fruit. They chew the fruit to obtain the juice. Very soft fruits such as bananas are swallowed, but usually the bat spits out the fruit pulp and seeds once it has extracted all the juice. The Indian flying fox also feeds on the juice and pollen of various tree flowers.

Behavior and reproduction: During the day Indian flying foxes roost in large camps in trees. These sites are out in the open. Camps may contain several hundred to several thousand flying foxes. Colony size changes with the seasons, becoming smaller during the summer and increasing during the rainy season. These bats typically keep the same roost sites for many years, and the trees become stripped of bark and leaves over time. During the day the bats are noisy and active. At night they can fly great distances to forage for food.

Within the roost there is often a pecking order within the male population. The more dominant males, those that are larger and stronger, take the best roosting sites.

Indian flying foxes breed from July to October. When ready to give birth, the females will gather in upper branches of their roosting trees. Females have one offspring after a gestation period of 140 to 150 days. The baby will cling to its mother for about two months until it is almost full size.

Indian flying foxes and people: While it once fed mainly on wild fruit, the bat now increasingly feeds on cultivated crops of fruit trees, which has caused many people to consider these bats pests. Farmers have used various methods to get rid of these bats. These foxes are also hunted in parts of Pakistan for its fat, which is used for medicine. People have also cleared the trees from many of the islands where these bats live, causing the population to decline.

Conservation status: The Indian flying fox is not considered threatened by the IUCN. In Pakistan, this species is specifically exempted from protection under wildlife regulation. ∎

EGYPTIAN ROUSETTE (Rousettus aegyptiacus): SPECIES ACCOUNTS

Physical characteristics: Rousettes are relatively small compared to other Old World fruit bats. The head and body are approximately 4.5 to 5 inches long (11.4 to 12.7). These bats have a simple, doglike face and ears, large eyes, and a very short tail that sticks out. The tail is about 0.4 to 0.9 inches (1 to 2.2 centimeters) long. The fur of these bats is brown, and often tinged with gray.

Geographic range: Egyptian rousettes are found in southern, western, and eastern Africa, Egypt, the Middle East, and Cyprus.

Habitat: Egyptian rousettes roost in humid areas, such as dark caves and abandoned buildings. Most are found roosting in caves. In Cyprus, some colonies may move to open sites in March.

Diet: Rousettes feed on many kinds of soft fruits, the juice of hard fruits, and certain leaves. Figs and dates form its main diet in dry regions.

Behavior and reproduction: Egyptian rousettes roost primarily in caves. They also roost in buildings, ancient ruins, trees, and rock crevices. They can form colonies of up to several thousand individuals. In South Africa, camps had an estimated 7,000 to 9,000 bats. In Pakistan, these bats appear to form small roosting colonies of about twenty to forty individuals. The bats use smell to help them locate their food.

While Egyptian rousettes appear to have good vision, these bats also use echolocation. Scientists think they use echolocation to help them navigate in caves and at night. As opposed to the echolocation calls of many other bats, humans can hear the echolocation calls of rousettes. They make a clicking sound with their tongue.

Some populations breed two times during the year. Females have one offspring per year and gestation is about four to six months. In Egypt, a field study found they breed year round.

Egyptian rousettes and people: Fruit farmers are the most important threat to populations. In Turkey and Israel, rousette caves have been fumigated, filled with smoke or fumes in order to kill pests, or the caves have been closed off by walls.

Conservation status: Egyptian rousettes are not listed as threatened by the IUCN. ∎

DWARF EPAULETTED FRUIT BAT (Micropteropus pusillus): SPECIES ACCOUNTS

Physical characteristics: Dwarf epauletted fruit bats are relatively small. Their head and body length is approximately 2.6 to 3.7 inches
(6.7 to 9.5 centimeters). Males are larger than females. While the tail length varies among individual bats, it is never long, ranging from not having a tail to 0.2 inches (0.4 centimeters). Fur is typically a light brown with a paler color on the underside. The hair is moderately long, thick, and soft. At the base of the ear are small whitish tufts of hair and males have pouches in their shoulder with tufts of white hair.

Geographic range: Dwarf epauletted fruit bats are found in western, southwestern, and central Africa.

Habitat: These bats live in open woodlands and on the edges of forests. Dwarf epauletted bats have also been found between the leaves of dense bushes, usually close to the ground.

Diet: Dwarf epauletted bats feed on small fruits, nectar, and pollen. When eating the fruits, these bats place their mouths around the ripe fruit and slowly suck its juices. They then drop the uneaten fruit pulp when they are finished.

Behavior and reproduction: Little is known about the dwarf epauletted bat's behavior and mating behavior. Dwarf epauletted bats are independent, typically roosting alone, with one other bat, or in small groups of up to ten. These bats move about frequently and do not have a regular roosting spots or feeding areas. These bats may eat two and a half times their body weight in a single night. It digests quickly and disperses, spreads, large quantities of seeds as it flies between feeding sites.

These bats are polygamous (puh-LIH-guh-mus), having more than one mate. There are two breeding seasons. Studies in the Ivory Coast indicate that births peaks from about March to May and from September to November. The gestation period is five to six months. Young females can mate at six months and give birth at twelve months.

Dwarf epauletted fruit bats and people: There is no known relationship between dwarf epauletted bats and people.

Conservation status: Dwarf epauletted bats are not listed as threatened. ∎

QUEENSLAND TUBE-NOSED BAT (Nyctimene robinsoni): SPECIES ACCOUNTS

Physical characteristics: Queensland tube-nosed bats are also called eastern tube-nosed bats. These bats have nostrils shaped like tubes that jut out about 1 inch (2.5 centimeters). Researchers do not yet understand the purpose of these tubes. Their head and body length is 3 to 5.1 inches (7.5 to 13 centimeters) with a tail length of 0.8 to 1 inch (2 to 2.5 centimeters). These bats have light brown fur with a dark stripe down the back. Their wings are brown with yellowish spots.

Geographic range: Queensland tube-nosed bats are found in eastern Australia.

Habitat: These bats live in tropical rainforests and subtropical rainforests.

Diet: These bats feed on fruit.

Behavior and reproduction: Queensland tube-nosed bats roost on branches of trees that have thick vegetation. They are solitary and do not appear to roost in groups. The bats often fly very close to the ground as they search for food. Queensland tube-nosed bats are polygamous with one breeding season. Females generally have one offspring per year. Gestation is approximately four to five months.

Queensland tube-nosed bats and people: By clearing these bats' natural habitats, people have caused the population of this bat to decline.

Conservation status: Queensland tube-nosed bats are not listed as threatened by IUCN. They are listed as vulnerable in Australia's New South Wales Threatened Species Conservation Act. ∎

FOR MORE INFORMATION

Books:

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

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

Nowak, Ronald M. "Old World Fruit Bats." Walker's Mammals of the World 5.1 Online.http://www.press.jhu.edu/books/walkers_mammals_of_the_world/chiroptera/chiroptera.pteropodidae.html (accessed on July 2, 2004).

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

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

Periodicals:

Petersen, David. "Wait Until Dark." Backpacker (October, 1993): 24.

"Plants, Bats Magnify Neurotoxin in Guam." Science News (December 6, 2003): 366.

Thewissen, J. G. M., and S. K. Babcock. "The Origin of Flight in Bats." Bioscience (May 1992): 340–345.

Web sites:

Craig, P., ed. "Flying Foxes (Fruit bats)." Natural History Guide to American Samoa.http://www.nps.gov/npsa/book/index.htm (accessed on July 2, 2004).

"Digital Morphology." National Science Foundation Digital Library at the University of Texas. http://www.digimorph.org (accessed on July 2, 2004).

"Discover the Secret World of Bats." Bat Conservation International, Inc. http://www.batcon.org (accessed on July 2, 2004).

"Fruit bats." The Wild Ones. http://www.thewildones.org/Animals/fruitBat.html (accessed on July 2, 2004).

Lemke, Thomas O. "Marianas Fruit Bats Near Extinction." Bat Conservation International, Inc. http://www.batcon.org/batsmag/v3n1-1.html (accessed on July 2, 2004).

"Mammals of the CNMI" Commonwealth of the Northern Mariana Islands. http://www.cnmidfw.org/wildlife/index.html (accessed on July 2, 2004).