(Pteropus)
Class: Mammalia
Order: Chiroptera
Suborder: Megachiroptera
Family: Pteropodidae
Thumbnail description
The largest of all bats and best known of the pteropodids, with a dog-like facial appearance and very large, forward-facing eyes, hence the common name "flying foxes"; coloration ranges from light to dark brown and some have very distinctly colored mantles
Size
Head and body length 6.7–16 in (17–41 cm); forearm 3.3–9 in (8.5–23 cm); weight 0.4–3.5 lb (0.2–1.6 kg); wingspan 2–6 ft (0.6–1.8 m)
Number of genra, species
1 genus, 60 species
Habitat
Subtropical and tropical forests, caves, and swamps
Conservation status
Extinct: 5 species; Critically Endangered: 7 species; Endangered: 3 species; Vulnerable: 16 species; Lower Risk/Near Threatened: 3 species; Data Deficient: 2 species
Distribution
Islands of the Pacific and Indian Oceans, and from Pakistan across Southeast Asia to Australasia
Evolution and systematics
The family Pteropodidae is divided into two subfamilies, Macroglossinae and Pteropodinae, the latter of which includes the genus Pteropus, also known as the flying foxes. Pteropus is further divided into 17 species groups and about 60 total species, depending on authority. Fossil records of this and other chiropteran groups are scarce due to the delicate nature of the skeletal structure of bats, but pteropid fossils have been found in Europe from the middle Oligocene and Miocene periods, in Africa from the Miocene period, and in Madagascar and the East Indies from the Pleistocene period. Pteropus is assumed to have arisen in the Australo-Pacific during the early Miocene. Their closest relatives are those of the genus Acerodon, a similar group in both size and morphology.
Physical characteristics
Pteropus species are the largest of all bats, weighing up to 3.5 lb (1.6 kg) and with a wingspan of up to 6 ft (1.8 m) Fur is dense and coloration is grayish brown or black. These mammals are characterized by a yellow or grayish yellow contrasting mantle (covering portions of the head, neck, and upper shoulders). Variations among species do occur, such as in the spectacled flying fox (P. conspicillatus), which has a light ring around its eyes. The external ears are small and do not have a tragus, and the tail is absent. The second finger is independent of the third and a claw is present on the thumb. Eyes are very large, forward-facing, and highly adapted to both nocturnal and day vision—this allows flying foxes to easily recognize light colors, which assists in locating food sources.
Distribution
These mammals primarily inhabit islands of the Indian and Pacific Oceans, from Madagascar north to the Maldives and Sri Lanka, across Indonesia, and into the middle Pacific on the island groups of Caroline, Tonga, and Samoa, as far east as the Cook Islands. On the mainland, Pteropus species are found from Pakistan in the west across India and Southeast Asia to Australia.
Habitat
Flying foxes inhabit tropical coastal areas such as mangrove forests, primary and secondary growth rainforest, lowland dry forest, swamps, and occasionally caves. Most species roost high above the canopy in a ridge of emergent trees.
Behavior
Flying foxes are most active in the evening and at night. They roost in trees by day, and many of the larger species do so in extremely large groups called "camps," which range in size from a few dozen individuals up to 250,000. When resting in the daylight hours, they hang from branches by one or both feet with wings wrapped around their bodies, though there is still sizable activity among the camp as the bats move from one spot to another. At dusk, when the time to forage arrives, Pteropus species will flap their wings until their bodies are parallel with the ground—only then do they release the branch and initiate flight.
Migration among flying foxes depends primarily on the seasonal availability of food sources. They do not migrate over particularly long distances, but instead travel between winter and summer roosts when fruits or blossoms are ready for the season. Mainland species will travel about 30 mi (50 km) to reach a new feeding site, and island groups may relocate to neighboring islands or to an accessible mainland area. Colonies will often use the same roosting sites year after year.
Flying fox vocalizations are in the range of 4–6 kHz. Vocalizations play an important role in feeding, mating, territorial disputes, and interaction with infants. In the case of the gray-headed flying fox (P. poliocephalus), at least 30 different kinds of calls have been documented.
Feeding ecology and diet
Pteropus species primarily consume fruit, nectar, and pollen. They are able to locate food using highly developed senses of vision and smell (like most fruit bats, members of this genus do not orient themselves using echolocation). Flying foxes employ optimal foraging (seeking the greatest ratio of benefit versus the amount of time and energy spent) as well as searching and handling techniques when going out to feed.
Once food is acquired, the bat will take it to a nearby roost and eat while hovering, or hang from a branch while using one foot to hold the fruit. Juice is the chief source of food for these mammals; it is consumed by compressing bits of pulp against the rigid palate of the mouth, swallowing the juice, and spitting out the pulp and seeds. If the pulp is soft, however, it may be occasionally eaten as well. They drink while traveling to or from a feeding location, skimming the surface of the water during flight. Some species drink seawater in an effort to acquire minerals that are unavailable in other food sources.
Owing to the pursuit of nectar, flying foxes have developed a working relationship with several plants within their habitat. Flower pollination and dispersal of seeds is of course beneficial to these organisms, and certain fruits and trees are specialized to attract fruit bats—some are lightly colored (sea almond trees, Terminalia catappa) while others have a strong odor (mangos, Mangfiera indiaca). Trees such as the durian (Durio zibethines) bloom only at night, easily able to attract the eye of a passing pteropid at peak feeding time.
Reproductive biology
During the summer, when fruit and blossoms are mature and in good supply, flying foxes organize camps. Mating takes place at this time and small groups, or harems, form. Males soon become very territorial over the females and the roosts, marking their areas using a scent gland located on the throat.
Females are seasonal breeders and usually produce one young per year; they begin to breed at two years. During mating season, flying foxes will mate more than once per day and over the course of several days. Ovulation takes place from February to April, and births occur from September to November. Lactating lasts about six weeks, and most of the female's time during the remainder of the year is spent caring for the young.
The gestation period of the flying fox is six months. During that time, the sexes begin to segregate and pregnant females form a colony; each female then helps to care for the others by mutual grooming. Birth occurs during the day—when it is imminent, the female hangs by her thumbs and feet and licks her genital area until the pup's head begins to emerge—this can last up to several hours. After birth, the pup moves itself into a suckling position and attaches itself to a nipple. The mother will fly with her young for about two to three weeks.
The pup has light fur, the eyes are closed, and the ear flaps are down. The mother keeps her wings wrapped around the pup for warmth. After approximately three weeks, it becomes too heavy to carry with her and is left with the other young. Upon the mother's return, she is able to recognize her offspring by its unique vocalizations. In about a month, the young become better coordinated and begin to explore, and by January and February, they begin to form small groups near their mothers. Once they become able to care for themselves, the mother will again begin to accept the advances of a male.
Conservation Status
The IUCN Red List ranks seven species as Critically Endangered, three species as Endangered, 16 species as Vulnerable, three species as Lower Risk/Near Threatened, two species as Data Deficient, and five species as Extinct.
The most serious threat to flying fox populations is probably deforestation. The removal of primary forest not only limits habitat in the most basic sense, but it also encourages additional loss—the logging processes used in these areas tend to inhibit growth of new canopy, and the elimination of large sections of forest leaves the remaining habitat even more vulnerable to the tropical storms that frequently strike island environments. The mass conversion of mangrove swamps into shrimp farms has also had a devastating effect on certain species, most notably the Pohnpei flying fox (P. molossinus).
Some Pteropus species are also losing ground due to illegal wildlife trade, human use for food, and extermination—flying foxes are often considered by orchard growers to be destructive agricultural pests. Populations can sometimes be disturbed by predation as well. An example is the brown tree snake (Boiga irregularis), which was introduced on Guam in the 1940s and has had a significant impact on bat populations since. Other enemies include predatory birds, such as owls and falcons.
Significance to humans
All over their range, flying foxes have been considered a delicacy for centuries, and this is especially so for the Chamorro people of Guam and the nearby Northern Marianas Islands. Traditionally, the animal (fur, wings, and innards included) is boiled in coconut milk and eaten in its entirety, usually during ceremonial or otherwise special occasions. Samoan islanders use branches bound to the end of long poles to snag the animal and pull it to the ground, while aboriginal Australians have also been known to use specialized methods to hunt these mammals for food.
Flying foxes have occasionally been considered beneficial for medical use. In the 1970s, Indian flying foxes (P. giganteus) in Pakistan were harvested for their fat, which was thought to be a cure for rheumatism. Still, by far the most notable contribution is that of pollination and seed dispersal. As a whole, Pteropus plays an integral role in the survival of 300 species of plants across its range, about half of which are regularly used by humans for nourishment, materials, and medicine.
Species accounts
Island flying foxMadagascar flying fox
Blyth's flying fox
Livingstone's fruit bat
Marianas fruit bat
Tongan flying fox
Indian flying fox
Black flying fox
Rodricensis flying fox
Spectacled flying fox
Big-eared flying fox
Little red flying fox
Resources
Books:Altringham, John D. Bats, Biology, and Behavior. New York: Oxford University Press, 1996.
Bonnacorso, Frank J. Bats of Papua New Guinea. Chicago: University of Chicago Press, 1998.
Buchmann, Stephen L., and Gary Paul Nabhan. The Forgotten Pollinators. Washington, DC: Island Press, 1997.
Crichton., Elizabeth G., and Phillip H. Krutzsch, eds. Reproductive Biology of Bats. New York: Academic Press, 2000.
Hall, Leslie, and Greg Richards. Flying Foxes, Fruit and Blossom Bats of Australia. Malabar, FL: Krieger Publishing Company, 2000.
Kunz, Thomas, and Paul Racey, eds. Bat Biology and Conservation. Washington, DC: Smithsonian Institution Press, 1998.
Mickleburgh, Simon, Anthony M. Hutson, and Paul Racey. Old World Fruit Bats: An Action Plan for Their Conservation. Gland, Switzerland: IUCN, 1992.
Neuweiler, Gerhard. The Biology of Bats. New York: Oxford University Press, 2000.
Nowak, Ronald, ed. Walker's Mammals of the World, 6th ed. Baltimore and London: The John Hopkins Unversity Press, 1999.
Taylor, Peter John. Bats of Southern Africa. Pietermaritzburg: University of Natal Press, 2000.
Periodicals:Banack, Sandra Anne. "Diet Selection and Resource Use by Flying Foxes (Genus Pteropus)." Ecology 79 (1998): 1949–1967.
Fujita, Marty. "Flying Foxes and Economics." Bats 6, no. 1 (1998): 49.
Rainey, William E. "The Flying Foxes: Becoming a Rare Commodity. Bats 8, no. 1 (1990): 69.
Other:"Family Pteropodidae." University of Michigan Animal Diversity Web. [23 June 2003].
Martin, Len. "The Effects of Culling the Flying Foxes, Pteropus conspicillatus in Northern Queensland, and Pteropus poliocephalus in Victoria, NSW and Southeast Queensland." [23 June 2003].
Thatcher, Oliver. "Destruction of Fruit Bat Habitat." [23 June 2003].
[Article by: Kate Kretschmann; Robin L. Hayes]
