Pteropus dasymallusRyukyu flying fox

Geographic Range

Pteropus dasymallus (Ryukyu flying-fox) range from the Ryukyu islands of Japan (Kuchinoerabu, Takara, Okinawa, Ishigaki, Iriomote, Hatoma, Obama, Yonakuni and some smaller islands) through parts of Taiwan (Kashoto Island, east coast Taiwan, and the Daito Islands). (Thatcher, 2004; Yoshiyuki, 1989)


Ryukyu flying-foxes use forests for daytime roosting.

Physical Description

Ryukyu flying-foxes are in the suborder Megachiroptera. Key characteristics of this suborder are that they have a well developed premaxillary bone, a postorbital process is present, they lack a tragus and a noseleaf, and their teeth are adapted for eating fruit. There are 5 subspecies of Ryukyu flying-foxes. They are P. d. daitoensis (Daito fruit bat), P. d. dasymallus (Erabu fruit bat), P. d. formosus (Taiwanese fruit bat), P. d. inopinatus (Orii's fruit bat), and P. d. yayeyamae (Yaeyama fruit bat). There are some character variations among the subspecies. Pteropus dasymallus daitoensis has brown wings and a yellow belly and back. The sides of the back are brown. The body is 221 mm long and forearm length 134 mm. Pteropus dasymallus dasymallus is the largest in size and darkest in color of the subspecies. The fur coloration consists of a blackish head and face, body is usually dark brown to black, and a cream colored area around neck. The forearm measured at around 137 mm. Pteropus dasymallus formosus is thought to be extinct in the wild. Pteropus dasymallus inopinatus has a brown muzzle, and it has a patch of darker fur that interrupts the white collar around its neck. Pteropus dasymallus inopinatus has an exposed lacrimal foramen. Pteropus dasymallus yayeyamae is the smallest in size among the 4 wild subspecies. The fur color varies on the dorsal and ventral sides of this subspecies. The head is usually brown and the neck a cinnamon color. (Thatcher, 2004; Yoshiyuki, 1989)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    435 g
    15.33 oz


Pteropus dasymallus have low reproductive rates. In most fruit bats females don't give birth for the first time until they are one or two years old (Mickleburgh et al. 1992). One young is born at a time with a gestation period of 4 to 6 months. In P. d. daitoensis mating takes place between November and early January and birth between May and June (Thatcher 2004). (Mickleburgh, et al., 1992; Thatcher, 2004)

  • Breeding season
    Mating takes place between November and early January
  • Range number of offspring
    1 (low)
  • Average number of offspring
  • Range gestation period
    4 to 6 months
  • Range age at sexual or reproductive maturity (female)
    1 to 2 years


  • Average lifespan
    Status: captivity
    24 years


Pteropus dasymallus roost in trees. The subspecies P. d. daitoensis may roost singly, in small groups, or even large camps. This subspecies also changes roosting sites (Thatcher 2004). Pteropus often form large groups on branches (Mickleburgh et al. 1992). The other subspecies live in colonies and usually stay at the same roosting sites. (Thatcher 2004, Species Under Threat 1998) ("Species Under Threat", 2000; Mickleburgh, et al., 1992; Thatcher, 2004)

Communication and Perception

Food Habits

Pteropus dasymallus feeds almost entirely on plants and their products. Fruit makes up the bulk of the diet. Figs seem to be one of the animal's favorites. Other plant products that are eaten are the flowers and leaves. Flowers are eaten in the spring and leaves year round. Insects may also be a part of the diet of this species in the summer and autumn. One study showed that P. d. dasymallus has a more diverse diet than any other pteropodid bats ever studied. Their diet includes bark, 17 species of fruit, nine species of leaves, five species of flowers, and eight species of insects on Kuchinoerabu Island. (Thatcher, 2004; Thatcher, 2004)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • fruit
  • flowers

Ecosystem Roles

Ryukyu flying-foxes are economically important because they pollinate wild and commercial plants. ("Species Under Threat", 2000)

  • Ecosystem Impact
  • disperses seeds
  • pollinates

Economic Importance for Humans: Positive

The 5 subspecies pollinate and disperse seeds important to the timber industry, food crops, and some medicinal plants. ("Species Under Threat", 2000)

  • Positive Impacts
  • pollinates crops

Economic Importance for Humans: Negative

Pteropus dasymallus do eat commercial fruit crops.

Conservation Status

Deforestation, hunting, and typhoons are threats to populations of P. dasymallus. Clearing of forest for agriculture takes away roosting and food supplies for these bats. Pteropus dasymallus formosus is now believed to be extinct in the wild. The extinction of this subspecies in the wild is believed to have been caused by hunting and deforestation (Thatcher 2004). Typhoons have a greater affect on forest structure because of deforestation. Smaller patches of trees are then more easily knocked down by the wind leaving less and less habitat. Reproductive factors also lead to conservation problems. Ryukyu flying-foxes have a low reproductive rate, making them unable to recover quickly after population declines. (Thatcher 2004, Mickleburgh et al. 1992, Species Under Threat 1998). ("Species Under Threat", 2000; Mickleburgh, et al., 1992; Thatcher, 2004)


Brian Putz (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.



uses sound to communicate


Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


an animal that mainly eats leaves.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


an animal that mainly eats fruit


An animal that eats mainly plants or parts of plants.

island endemic

animals that live only on an island or set of islands.


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


active during the night


an animal that mainly eats all kinds of things, including plants and animals


found in the oriental region of the world. In other words, India and southeast Asia.

World Map


chemicals released into air or water that are detected by and responded to by other animals of the same species


rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate


uses sight to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.


2000. "Species Under Threat" (On-line). Accessed 01/07/04 at

Mickleburgh, S., A. Hutson, P. Racey. 1992. Old World Fruit Bats An Action Plan for their Conservation. Oxford, UK: Information Press.

Thatcher, O. 2004. "Regional Conservation Issues, Japan and Taiwan" (On-line). Lubee Bat Conservancy. Accessed 01/07/04 at

Yoshiyuki, M. 1989. A Systematic Study of the Japanese Chiroptera. Tokyo, Japan: National Science Museum.