Glirulus japonicusJapanese dormouse

Geographic Range

Japanese dormice are found on the Japanese islands of Honshuu, Shikoku, and Kyuushuu. ("Japanese Dormouse - Glirulus japonicus", 2009)


Japanese dormice live in a variety of habitats. They are arboreal and mostly found in deciduous and coniferous forests at medium to high elevations, between 400 and 1800 meters. Populations of Japanese dormice have also been found in arid areas, mountains, and in lower elevation, warm forests. ("Japanese Dormouse - Glirulus japonicus", 2009)

  • Range elevation
    400 to 1800 m
    1312.34 to 5905.51 ft
  • Average elevation
    900 m
    2952.76 ft

Physical Description

Japanese dormice are similar in appearance to both mice and squirrels. They have a thick layer of soft, hazel or brown fur with a dark brown or black dorsal stripe. They have tufts of hair on the anterior side of the ears and the tail is bushy and flattened dorsally. The hindfeet have four digits and the forefeet have five, all of which have short, hinged claws accompanied by soft pads that enable them to swiftly run along the underside of hanging tree limbs. Japanese dormice, like other dormice, hibernate during cold weather or times of little food. The sexes are alike, ranging in mass from 14 to 40 g and 105 to 135 mm head and body length. ("Japanese Dormouse - Glirulus japonicus", 2009; Nowak, 1999; Shibata and Kawamichi, 2006)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    14 to 40 g
    0.49 to 1.41 oz
  • Range length
    105 to 135 mm
    4.13 to 5.31 in


Japanese dormice are generally solitary. In May, males emerge from hibernation to find a mate, relying heavily on their well developed ability to vocalize. Females respond to the vocalizations of males with their own calls. Males mate with several females, as their home range often encompasses the home range of several females. ("Japanese Dormouse - Glirulus japonicus", 2009; "Japanese Dormouse - Glirulus japonicus", 2009)

Japanese dormice mate in the late spring to early summer. Gestation lasts for about a month and an average of 4 young are born between the months of June and July. Young are weaned after about 18 days, reaching independence at around 4 to 6 weeks old. Sexual maturity is attained at around 1 year. ("Japanese Dormouse - Glirulus japonicus", 2009; "Japanese Dormouse - Glirulus japonicus", 2009)

  • Breeding interval
    Japanese dormice breed actively in the spring and early summer
  • Breeding season
    Breeding occurs between the months of May and June.
  • Range number of offspring
    2 to 6
  • Range gestation period
    4 to 6 weeks
  • Range weaning age
    15 to 21 days
  • Range time to independence
    4 to 6 weeks
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Japanese dormice have relatively low parental investment per offspring because of their large litter sizes. Young are weaned at around 18 days and become completely independent between 4 and 6 weeks old. Males have no involvement with their offspring after copulation. Females provide all the care necessary to ensure that their young survive until independence. ("Japanese Dormouse - Glirulus japonicus", 2009; Shibata and Kawamichi, 2006)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female


Japanese dormice have an average life span in the wild of between 3 and 5 years. The longest lifespan recorded for a Japanese dormouse is 6 years. ("Japanese Dormouse - Glirulus japonicus", 2009; "Ministry of the Environment, Government of Japan", 2007)

  • Range lifespan
    Status: wild
    6 (high) years
  • Typical lifespan
    Status: wild
    3 to 5 years


Japanese dormice are solitary, nocturnal, and highly arboreal, possessing feet that are specialized for clinging to the underside of hanging branches and running upside down. They travel over a relatively large home range in search of food. Dormice are well know for their notably long hibernation period. In fact, the name "dormouse" comes from an archaic Anglo-Norman word, "dormeus", meaning sleepy one. Japanese dormice are vocal during mating season. They weave intricate nests out of lichen and bark. ("Japanese Dormouse - Glirulus japonicus", 2009; MacDonald, 2006; Nowak, 1999; Shibata and Kawamichi, 2006)

Home Range

Male Japanese dormice travel over a much larger home range than do females. However, females also travel over a home range size that is surprisingly large compared to other rodents of similar size. ("Japanese Dormouse - Glirulus japonicus", 2009)

Communication and Perception

Japanese dormice rely heavily on olfaction and mark their nests with urine in order to establish territory. They use tactile cues extensively when getting around their arboreal habitats at night. When they emerge from hibernation in the spring, they produce loud vocalizations that enable them to locate potential mates. ("Japanese Dormouse - Glirulus japonicus", 2009)

Food Habits

Japanese dormice are omnivorous, eating seeds, fruit, insects, and bird eggs. They store food in their nesting areas for later use. ("Japanese Dormouse - Glirulus japonicus", 2009; Shibata and Kawamichi, 2006)

  • Animal Foods
  • eggs
  • insects
  • Plant Foods
  • seeds, grains, and nuts
  • fruit


Little is known about predators of Japanese dormice. They tend to live at low population densities and are not a reliable or abundant source of food for many potential predators. Their modified suspensory locomotion and nocturnal habits enable them to move through forests relatively unnoticed. ("Japanese Dormouse - Glirulus japonicus", 2009; "Ministry of the Environment, Government of Japan", 2007)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Japanese dormice are important in their native ecosystems because they eat large quantities of insects, especially during insect population outbreaks. Their role in distributing seeds of fruiting plants it also noted. Otherwise, little is documented concerning the ecological roles of this species. ("Japanese Dormouse - Glirulus japonicus", 2009; "Ministry of the Environment, Government of Japan", 2007; "UNEP-WCMC", 2007; MacDonald, 2006; Nowak, 1999; Shibata and Kawamichi, 2006)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Japanese dormice are avid insect predators and their presence in ecosystems helps to control populations of insects. In Japan, agriculture is particularly vulnerable to locusts, and Japanese dormice help control seasonal swarms of such insects. ("Japanese Dormouse - Glirulus japonicus", 2009; "Ministry of the Environment, Government of Japan", 2007; MacDonald, 2006)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Glirulus japonicus on humans. ("Japanese Dormouse - Glirulus japonicus", 2009; "Ministry of the Environment, Government of Japan", 2007; "UNEP-WCMC", 2007; MacDonald, 2006; Nowak, 1999; Shibata and Kawamichi, 2006)

Conservation Status

The IUCN lists Glirulus japonicus as least concern. The Ministry of Japan has designated Japanese dormice as an endangered National Monument and their habitats are under government protection throughout Japan. ("Ministry of the Environment, Government of Japan", 2007)

Other Comments

Glirulus japonicus is known in Japan as 'Yamane' (山鼠), or "mountain rat", and has long been an important spiritual icon in the Shinto religion. ("Ministry of the Environment, Government of Japan", 2007)


Matthew Shaw (author), University of Oregon, Stephen Frost (editor, instructor), University of Oregon, Tanya Dewey (editor), Animal Diversity Web.



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.


to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate


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.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

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.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

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


having more than one female as a mate at one time


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.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season


remains in the same area


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


lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"


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).


Living on the ground.


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.


2009. "Japanese Dormouse - Glirulus japonicus" (On-line). Accessed January 21, 2009 at

2007. "Ministry of the Environment, Government of Japan" (On-line). Accessed January 20, 2009 at

2007. "UNEP-WCMC" (On-line). Accessed January 20, 2009 at

MacDonald, D. 2006. The Encyclopedia of Mammals. Oxford: Oxford University Press.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: John Hopkins University Press.

Shibata, F., T. Kawamichi. 2006. Daily rest-site selection and use by the Japanese dormouse. Journal of Mammalogy, 85: 30-37.