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Fragmentation of forest habitat has negative effects on arboreal mammals, compromising their natural dispersal and foraging movements. This paper describes an evolving series of mitigation measures aimed at creating cost-effective continuity pathways for arboreal mammals in Japan. The projects have focused on the endemic Japanese dormouse (Glirulus japonicus) a scarce, but popular and iconic species which provides an effective vehicle for environmental education and public engagement.

This study investigated the little known winter ecology of Japanese dormice by monitoring body temperature patterns and winter activity in captive and free-living animals. Before onset of hibernation, animals exhibited a transitional phase characterized by frequent bouts of daily torpor. During hibernation itself, dormice aroused periodically from torpor but never foraged during arousals. Torpor bout duration tended to be shorter around the beginning and end of the hibernation period than during the intervening mid-hibernation period. In a further radio-tracking study of two free-living dormice, both were observed to construct a shallow underground hibernaculum at a depth of 1–5 cm and to enter hibernation alone. One individual left the nest after it was disturbed, while the other dormouse stayed in its nest and continued hibernating normally, exhibiting periodic arousal but never feeding or moving from the hibernaculum. These first detailed observations of hibernation in Japanese dormice are in good accordance with previous studies of European dormouse species.

We previously revealed the presence of six genetically distinct matrilineal populations of the Japanese dormouse Glirulus japonicus in the distribution range of Honshu, Shikoku, and Kyushu islands. In this study, we extended this analysis using mitochondrial cytochrome b gene sequences (n = 96) and Y-chromosome-specific SRY gene sequences (n = 22) from individuals collected from Honshu, Shikoku, Kyushu, and Oki Dogo I. The cytochrome b sequence data allowed us to define precise geographic ranges of the six previously known and three newly found distinct matrilineal lineages: northeastern Honshu (I), east-central Honshu (II), west-central Honshu and the Kii Peninsula (III), the western part of Honshu (IV), Shikoku (V), westernmost Honshu and Kyushu (VI), the northern part of central Honshu (VII), the southern part of central Honshu (VIII), and Oki Dogo I. (IX). Our inference of geographic borders suggests that regions of lower and higher altitudes in the mountain systems played important roles in driving the hosting and separation of lineages, respectively. Six matrilineal lineages (I, II, V, VI, VIII, and XI) were shown to possess their own SRY haplotypes, while lineages III and IV shared one haplotype. These data together with our previous observation of nuclear ribosomal RNA gene variation indicate advanced populational subdivision in this species. It is thus evident that each of the populations, including those living at high latitudes and in limited geographic spaces, have survived for several million years. A specific ability to tolerate cold may have permitted G. japonicus to preserve anciently diverged lineages in each locality.

Eight microsatellite markers were developed for the Japanese dormouse (Glirulus japonicus), a natural monument and near-threatened species in Japan. The markers amplify in individuals from all of the mitochondrial lineages detected in a previous study. Numerous polymorphisms were detected in specimens from a local population in central Honshu (11-21 alleles per locus; n = 31) and from the entire distribution range of the species (19-41 alleles per locus; n = 152). These microsatellites will be useful in conservation genetic studies of G. japonicus.