865.
Japanese Dormouse
(Glirulus japonicus)
LC
Overview
With a thick, bushy tail and a dark stripe running down the centre of its back, the Japanese dormouse looks like a very small chipmunk. It is arboreal and nocturnal, sleeping during the day in a round nest in tree hollows or amongst the branches. The English name ‘dormouse’ means ‘sleeping mouse’, and like other species of dormice, this species hibernates during the winter months. Habitat loss has been the main cause of its decline.
Urgent Conservation Actions
Conservation of habitat is the key conservation action required.
Distribution
Japanese islands of Honshu, Shikoku, and Kyushu.
Media from ARKive
ARKive image - Japanese dormouse hibernating
Evolutionary Distinctiveness
Order: Rodentia
Family: Gliridae
The family Myoxidae (also known as Gliridae) contains 28 species in 9 genera. It is an ancient family, thought to have originated sometime during the middle Eocene (some 45 million years ago). In the Pleistocene (1.8 million - 10,000 years ago), giant species evolved on some Mediterranean islands. Today, dormice are intermediate in form and behaviour between mice and squirrels. G. japonicus is the only member of the genus Glirulus. Despite some genetic differences between different populations, it is generally regarded as a single species distributed over the three main islands of Japan.
Description
Size: 
Head and body length: 65-80 mm
Tail length: 40-55 mm.
Weight: 14-40 g
With a thick, bushy tail and a dark stripe running down the centre of its back, the Japanese dormouse looks like a very small chipmunk. Its pale olive brown fur is soft and thick. The dorsal stripe varies in width and is sometimes very obscure. The species has prominent eyes and rounded ears which are often hidden behind tufts of long hair. The tail is flattened from top to bottom.
Ecology
Very little is known about the ecology of this species. It is arboreal and nocturnal. During the day it shelters in a tree hollow or in the branches of trees or shrubs. The round nest is covered on the outside with lichens and lined on the inside with bark. Like other dormice, this species hibernates during the winter months. During the late summer and early autumn the species builds up stores of fat in preparation for hibernation. It eats seeds, fruit, insects and birds’ eggs. The dormice hibernate in a curled-up, circular position in their nests. They may awake from time to time to eat food they have stored.

Japanese dormice have large home ranges relative to their body mass. Males have larger home ranges and move for longer distances at night than females. The young are usually born in June or July, with females occasionally giving birth to a second litter in October. The usual litter size is thought to be 3-5, born after a gestation period of approximately one month.
Habitat
This dormouse inhabits mountain forests, usually from about 400 to 1,800 meters in elevation.
Distribution
Japanese islands of Honshu, Shikoku, and Kyushu.
Population Estimate
Unknown.
Status
Classified as Endangered (EN A1c) on the 2006 IUCN Red List of Threatened Species.
Threats
Habitat loss is thought to be the main reason for the species’ decline.
Conservation Underway
The species occurs in the Shirakami-sanchi (Shirakami mountains) Natural World Heritage Site. Dr. Shusaku Minato, a researcher on the Japanese dormouse has invented a ‘Yamane Bridge’ which enables the species to move freely across the busy motorways that cut through forests. Nesting boxes have been placed on the bridge and in several places where the species is known to occur. The Kiyosato Educational Experiment Project (KEEP) is supporting research on the species in the Yatsugatake region. The Yamane museum has displays and classes which aim to educate visitors about the need to preserve the species’ habitat.
Conservation Proposed
Conservation of habitat is the key conservation action required.
Links
United Nations Environment Programme (UNEP)/World Conservation Monitoring Centre (WCMC) Protected Areas Programme
The UNEP WCMC is a collaboration between the United Nations Environment Programme, the world's foremost intergovernmental organization, and WCMC 2000, a UK-based charity. This programme aims to evaluate and highlight the many values of biodiversity and put authoritative biodiversity knowledge at the centre of decision-making.
References
Baillie, J. 1996. Glirulus japonicus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. Downloaded on 19 July 2006.

Nowak, R.M. 1999. Walker's Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Suzuki, H., Minato, S., Sakurai, S., Tsuchiya ,K., and Fokin I. M. 1997. Phylogenetic position and geographic differentiation of the Japanese dormouse, Glirulus japonicus, revealed by variations among rDNA, mtDNA and the Sry gene. Zoological Science 14(1): 167-73.

Distribution map based on data provided by the IUCN Global Mammal Assessment.

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