Pteromys momongaJapanese flying squirrel

Geographic Range

Pteromys momonga, also known as the Japanese flying squirrel, is found on Honshu and Kyushu Islands. (Nowak, 1999)


The habitat of this species consists of boreal evergreen forests. On a smaller spatial scale, they locate their nests (composed of moss or lichen) at the junction of a branch and the trunk of a tree, particularly pine or spruce. (Nowak, 1999)

Physical Description

The head and body length of P. momonga is 120 to 228 mm, and the tail length is between 108 and 127 mm. The mass of these animals has not been reported, and no sexual dimorphism has been described. Their coloration is a silvery to buffy gray on the dorsal surface, and a buffy white on the ventral surface. The gliding membrane extends from the ankles to the wrists, but they lack a membrane between the hind legs and the base of the tail. They blend so well with the coloration of the tree bark that they practically become invisible. (Nowak, 1999)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    120 to 228 mm
    4.72 to 8.98 in


No species-specific development information is available, but the following is a general pattern in flying squirrels. The young squirrel is naked at birth, with blood vessels and internal organs visible through the skin. The pup is born completley helpless, relying on its mother for food. After a week, the skin darkens and short hairs begin to develop. Some babies can right themselves at this age. At two weeks old, more fur develops, the toes are separated, and the ear canals begin to open. The infant is soon able to move its tail and facial whiskers voluntarily. At three weeks lateral hairs begin to develop on the tail and the baby responds to loud noises. At four weeks, the baby is completely furry, and the eyes open. They move about energetically and sample food that the mother brings. At five weeks they start some exploration outside of the nest (Wells-Gosling, 1985).


The mating system of these animals has not been reported.

A pair of adults usually shares a nest. There is a gestation period of approximately 4 weeks. Birth of the young occurs predominantly in May, but in June or early July, a second litter is often produced. There can be a range of 1 to 5 young per litter, with an average of 2 or 3. The young are weaned after 6 weeks. (Nowak, 1999)

  • Breeding interval
    These animals apparently breed once or twice annually.
  • Breeding season
    P. momonga is reported to breed from May through July.
  • Range number of offspring
    1 to 5
  • Average number of offspring
    2 or 3
  • Average gestation period
    4 weeks
  • Average weaning age
    6 weeks

Details of the parental behavior of this species have not been reported. Young sciurids are typically altricial. The mother nurses the young for approximately six weeks, and presumably grooms and otherwise cares for them during that time. It is not known what role the male may play in parental care. (Nowak, 1999)

  • Parental Investment
  • altricial
  • pre-weaning/fledging
    • provisioning
      • female


No information was found specifically for P. momonga, but other flying squirrels usually live 4 to 5 years. (Wells-Gosling, 1985)


Japanese flying squirrels are strictly nocturnal and silent in flight. They rarely remain on the ground, instead spending their time in the trees. During the day, these animals can be found in their nests or in a hole in trees. They emerge at dusk, moving quickly about the treetops. This is probably a predator-avoidance adaptation. Sometimes many individuals of the same sex are found in a single tree. The exception to this is during the mating season, when both sexes occupy the tree. (Ando, et al., 1986; Nowak, 1999)

Home Range

The home range size has not been reported for this species.

Communication and Perception

Data on ccommunication in P. momonga is lacking, but this species probably relies mainly on vocal communication, such as chittering noises. This would make them like other flying squirrels.

Mothers keep their young in a tree nest for at least six weeks, and it is likely that there are some forms of tactile communication occurring in that context. (Wells-Gosling, 1985)

Food Habits

The diet of Japanese flying squirrels consists of nuts, pine seeds, the buds and bark of certain trees, fruits, and probably some insects. Their forepaws may play only a supplemental role in holding food, which was exhibited by a study done using bait to observe how the species eats in comparison to others. The study also found that when the squirrels were on a perch, they had to turn their bodies sideways in order to bring food to the mouth. (Ando, et al., 1986)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit
  • flowers


Specific predators for P. momonga have not been reported. However, as small, nocturnal mammals, they are probably subject to predation by owls.

Japanese flying squirrels posses several features which are adapted to avoid predators. Their cryptic coloration helps them blend into their environment, so that they are less easily detected by predators. They also lie so flat against the tree that they look like an inconspicuous lump on the bark. It is thought that their erratic, quick movements help them to avoid predators also. In addition, they might use their gliding ability to escapre from predators. (Nowak, 1999)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Since P. momonga eats pine seeds, it most likely serves as a seed disperser for pine species. It may also be impotant in local food webs. (Nowak, 1999)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Flying squirrels throughout the world have been marketed in the pet trade and used for their fur. (Wells-Gosling, 1985)

  • Positive Impacts
  • pet trade
  • body parts are source of valuable material

Economic Importance for Humans: Negative

This species does not adversley affect humans, since it resides in forested landscapes where it seldom comes into contact with people.

Conservation Status

There hasn't been any analysis done to determine biodiversity or conservation for P. momonga.


Nancy Shefferly (editor), Animal Diversity Web.

Tracy Watkins (author), Humboldt State University, Brian Arbogast (editor), Humboldt State University.



living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map


uses sound to communicate


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.


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


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.


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.


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 mainly eats seeds


An animal that eats mainly plants or parts of plants.

island endemic

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


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


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

pet trade

the business of buying and selling animals for people to keep in their homes as pets.


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


associates with others of its species; forms social groups.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


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.


Ando, M., S. Shiraishi, T. Uchida. 1986. Feeding Behavior of Three Species of Squirrels. Behaviour, 95: 76-86.

Nowak, R. 1999. Walkers Mammals of the World, Sixth Edition. Baltimore: Johns Hopkins University Press.

Wells-Gosling, N. 1985. Flying Squirrels. USA: Smithsonian Institute Press.