Classification and Range
Bats belong to the order Chiroptera which aptly means “hand-wing.” More than 1,100 species exist. The two sub-orders are Megachiroptera or “megabats” and Microchiroptera, the smaller, echolocating and mostly insectivorous bats. Old World fruit bats of Africa, Asia and Australia, commonly called “flying foxes,” make up the single megabat family Pteropodidae. The genus Pteropus contains around 60 species that are found throughout tropical and sub-tropical Asia, Australasia and Pacific islands. The Indian flying fox has a widespread range on the Indian sub-continent that extends from Pakistan to Southeast Asia and China, and south to the Maldive Islands. Pteropus giganteus is also known as the Greater Indian fruit bat.
Indian flying foxes inhabit tropical forests and swamps along coasts and bodies of water. They require large trees capable of holding huge bat colonies. Tree species used include banyan, tamarind and fig.
All bats possess wings with a clawed thumb and four elongated digits between two layers of skin. They have long-toed feet with sharp claws enabling them to roost hanging upside down. Old World fruit bats share common characteristics designed to find and consume their fruit-oriented diets. A claw on their second finger enhances grasping ability. They have long snouts with excellent sense of smell, long tongues to reach into plants, and dentition for piercing tough rinds and mashing pulp. The large eyes possess excellent night vision and perhaps some color perception to distinguish fruit from foliage. Their ears are simple and small compared to the ears of echolocating bats. Most fruit bats have muted coloration of grays, browns or black with yellowish mantles; however, with its reddish brown fur and pointy ears, Pteropus giganteus truly looks like a flying fox. With wing spans up to 6 feet and weights more than 3 pounds, flying foxes are the largest bat species. While not the biggest fruit bat, Pteropus giganteus does live up to its name in comparison to the smallest, the long-tongued fruit bat with a 12 inch (30 cm) wingspan and weighing only .5 ounces (15 g).
Males generally larger, heavier
Head and body length: average 9 inches (23 cm)
Weight range: 1.3 to 3.5 pounds (.6 - 1.6 kg); females average 2 pounds (.9 kg)
Wingspan: 3.9 to 4.9 feet (1.2-1.5m)
Average 21 years; Oldest captive lived over 31 years
In the wild: Mainly frugivorous. Eats mainly figs, but also variety of fruit including mango, guava, banana, durian, neem and papaya, as well as blossoms and nectar. Raids cultivated fruit crops.
At the zoo: Apples, bananas, cooked sweet potato and carrots, mixed greens, vitamin and mineral supplements.
Reproduction - Mostly upside down
Bat reproduction occurs mostly upside down. Between July and October, Indian flying foxes mate while hanging in the midst of their large colony. A courting male fans his wings toward a female, follows her to grasp the back of the neck, and mates with her. No pair bonds occur and males have no role in parenting. Between February and May and after a long gestation of 140 to 150 days, the female produces a single pup and rarely twins. To give birth, the female hangs head up thus gravity assists the process. Newborn fruit bats weigh about one-fourth the female’s weight and have fully furred bodies and open eyes. With the infant securely clasped under a wing, the female returns upside down again. Mothers carry infants constantly their first three weeks. Later the young hang by themselves in the home tree, although females carry them to feeding sites. Young bats fly around 11 weeks and they wean by 5 months. Fruit bats become sexually mature at 1 1/2 years of age.
Lifestyle: Life in a Social Colony
Indian flying foxes reside in the same home or camp tree for years. The colony contains several hundreds even thousands of bats living on nearby trees. The bats erupt into loud chatter when an outsider approaches. Males protect the colony and dominant males claim the choicest resting spots: under dense branches during hottest times; near the top open to the sun when cold; and under branches during heavy rain. Fruit bats spend the daytime sleeping, resting, licking and grooming themselves and each other. They vocalize and their spread wings to claim territory. At dusk, they fly off together to feed. Their good senses of smell and sight locate ripe fruit sources. Fruit bats use their clawed digits to grasp fruit and they bite off pieces with their sharp teeth. They chew the fruit and crush it against their hard, ridged palates. Then they swallow the juice and spit out small pellets of pulp and seeds. Large flying foxes consume up to half their body weight daily. After hours spent feeding, resting and digesting, they return to the camp tree at dawn.
Life on the Wing
Bats are the only mammals capable of powered flight which requires both lightness and strength. The wing membrane stretched across the elongated finger digits is so thin that light can be seen though it. Bats have very light bones compared to other mammals. Flight muscles attach to shoulder blades and the breastbone. In contrast to the powerful upper body, most fruit bats lack weight bearing hind limbs for locomotion or even standing. At best, flying foxes crawl on the ground. With lighter and weaker rear quarters, bats hang upside down. Tendons in the hind legs lock claws onto surfaces without any effort. To launch into flight, they merely release their grip.
Flying foxes travel long distances in search of food sources. Nightly flights over 9 miles (15 km) are common; however, they may be up to 40 miles (64 km). To land, they slow to a stall or crash into foliage then grasp branches. Any damage to wing membranes and even broken bones heal quickly. Bats also use their wings for warmth and for fanning when too hot.
Life at Night
Most bats live a nocturnal lifestyle and spend the daylight hours in roosts. Since vast hordes of insects fly at night, the echolocating bats hunt with less competition. For fruit bats living in the tropics and sub-tropics, nighttime has other advantages. Long distance flights generate body heat, and cooler night temperatures help dissipate it. Flying during the heat of daytime could result in heat prostration or dehydration. Increased nighttime moisture enhances elasticity of the wing membrane. Night flight means fewer predators, yet another advantage.
Fruit bats and “bat-adapted” plants aid each other. Flying foxes pollinate and disperse seeds of many tropical plants. To attract these visual and scent-oriented nocturnal feeders, some plants evolved large white flowers, strong aromas, or large quantities of nectar and pollen.
Bats in Culture - Myths and Practices
In Western culture, bats often evoke fear and superstition. Many negative myths exist, such as being “as blind as a bat” and bats as dirty, blood-sucking, rabies transmitters. All bats can see - megabats have excellent sight and microbats rely on hearing and echolocation over vision. Bats keep themselves fastidiously clean with licking and grooming. Only three New World species of vampire bats consume blood and by licking not sucking. Both people and animals can contract rabies from bats, mostly from vampire bats, but the disease is more common in other wildlife species.
For centuries and in many Asian cultures, people hunt fruit bats as a meat source. Some traditional practices use bat meat or fat to treat medical conditions, such as rheumatism. Farmers may kill fruit bats as crop raiding pests. In China, the bat receives acceptance as a symbol of happiness and good luck. In some Indian villages, the Indian flying fox is sacred and protected from harm.
Location at the Zoo
Our Indian flying foxes are located in the Trail of Adaptations. Other nocturnal animals exhibited there include two-toed sloth and tamandua, an anteater.
Indian flying foxes have a “Least Concern” listing in CITES Appendix II. They exist in large numbers within an expansive range that includes protected areas. Nonetheless, fruit bats face declining numbers. Humans constitute their major predators along with raptors and snakes. Some governments classify them as “vermin” and allow extermination. Evidence points to flying foxes as hosts for some zoonotic diseases, such as Hendra and Nipah viruses which affect both humans and domestic animals. In India, The Wildlife Protection Act still considers all flying foxes as pests without distinction between the ten species which feed in forests and the three which raid cultivated orchards. Deforestation and cutting down huge roost trees create further problems for fruit bats.
Worldwide, over half of all bat species fall within threatened or near-threatened categories and face serious population decline. In the eastern U.S. over 5.5 million bats died from “white-nose syndrome” since 2008. The United Nations Environment Programme (UNEP) proclaimed 2011-2012 as Year of the Bat to coincide with the United Nations Year of Forests. Leading roles come from the Bat Specialist Group, Species Survival Commission of IUCN and the Organization of Bat Conservation. Year of the Bat promotes conservation, research and education. Flying foxes are a keystone species in the world’s tropical rainforests. They pollinate and disperse seeds of many tropical plants, for example kapok, durian, mango and banana. People collect bat guano, an excellent fertilizer. Microbats provide pest control in their nightly consumption of insects by the tons. Many ecological benefits come from bats.
Sources and Suggested Reading
“Amazing Bat Facts” www.batrescue.org/batfacts/batfacts.html
“Bat Facts” Encyclopedia Smithsonian. www.si.edu/Encyclopedia_SI/nmnh/batfacts.htm
Bat Specialist Group website. www.iucnbsg.org/about_bsg.html
“Bats” The Encyclopedia of Mammals. edited by Dr David Macdonald. pp 500-503. 1999
Marimuthu, G. “The Sacred Flying Fox of India” Bats Magazine. http://batcon.org/index.php/media-and-info/bats-archives.ftml?task=viewArticle&magArticleID=335
“More on Year of the Bat 2011-2012” www.yearofthebat.org/webedit/uploaded-files
Organization of Bat Conservation website. www.batconservation.org/drupal/indian-ff
“Pteropus giganteus” http://eol.org/pages/327167/entries/34293759/details
“White-Nose Syndrome (WNS)” National Wildlife Health Center www.nwhc.usgs.gov/disease_information/white-nose-syndrome/
Secret World of Bats - DVD 48 minute film originally shown on CBS with Bat Conservation International founder Merlin Tuttle and captures all aspects of bat behavior
Bats: Myth and Reality (1985) 16 minute video for grades 2-12 produced by Bat Conservation International emphasizing the ecological importance and conservation needs of bats worldwide.
Bats of America (1989) 16 minute video for grades 1-6 produced by Bat Conservation International offers an in-depth look at bats, their importance to ecosystems and their threats.
Discover Bats! (revised & updated 2009) Bat-education package produced by Bat Conservation International for grades 4-8.
Stellaluna by Janell Cannon. A children’s book about a young fruit bat.