By Matthew Shaw
Geographic Range
Japanese dormice are found on the Japanese islands of Honshuu, Shikoku, and Kyuushuu. ("Japanese Dormouse - Glirulus japonicus", 2009)
Other Geographic Terms:
island endemic 
.
Habitat
(1312 to 5904 ft; avg. 2952 ft)
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)
These animals are found in the following types of habitat:
temperate ; terrestrial .
Terrestrial Biomes:
forest ; rainforest ; scrub forest ; mountains .
Physical Description
(0.49 to 1.41 oz)
(41.34 to 53.15 in)
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 cm head and body length. ("Japanese Dormouse - Glirulus japonicus", 2009; Nowak, 1999; Shibata and Kawamichi, 2006)
Some key physical features:
endothermic ; heterothermic ; bilateral symmetry .
Sexual dimorphism: sexes alike.
Reproduction
Japanese dormice breed actively in the spring and early summer
Breeding occurs between the months of May and June.
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)
Mating systems:
polygynous .
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)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous .
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).
Lifespan/Longevity
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 and Government of Japan", 2007)
Behavior
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)
Other communication keywords:
duets ; scent marks .
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)
Primary Diet:
omnivore .
Animal Foods:
eggs; insects.
Plant Foods:
seeds, grains, and nuts; fruit.
Foraging Behaviors:
stores or caches food .
Predation
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 and 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 and Government of Japan", 2007; "UNEP-WCMC", 2007; MacDonald, 2006; Nowak, 1999; Shibata and Kawamichi, 2006)
Key ways these animals impact their ecosystem:
disperses seeds.
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 and Government of Japan", 2007; "UNEP-WCMC", 2007; MacDonald, 2006; Nowak, 1999; Shibata and Kawamichi, 2006)
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 and Government of Japan", 2007; MacDonald, 2006)
Ways that people benefit from these animals:
controls pest population.
Conservation Status
IUCN Red List: [link]:
Not Evaluated.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
State of Michigan List: [link]:
No special 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 and 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 and Government of Japan", 2007)
For More Information
Find Glirulus japonicus information at
Contributors
Matthew Shaw (author), University of Oregon. Stephen Frost (editor, instructor), University of Oregon.
Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.
