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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.

Nucleotide sequences of the mitochondrial D-loop region were examined in three wild rodents (Apodemus argenteus, Apodemus speciosus, and Myodes smithii) on the northern slope of Mt. Fuji, the highest mountain in Japan, to elucidate the past evolutionary and present anthropogenic processes shaping their genetic diversity. Nucleotide diversity, median-joining network, and mismatch distribution analyses suggested that A. argenteus has multiple divergent lineages, possibly due to multiple previous expansion events, whereas A. speciosus and M. smithii are younger lineages that could be derived from single expansion events. These findings indicate that Mt. Fuji plays an important role as a reservoir maintaining lineages through multiple past expansion events. Artificial infrastructure also affected the genetic diversity of the two Apodemus species, as populations of these species on the two sides of the Fuji Subaru Line roadway were genetically distinct. To construct a proper conservation strategy based on genetic diversity, we suggest that the past and present contributors to genetic diversity must be clarified. Such clarification is especially important for the Mt. Fuji environment, which harbors rich biodiversity but also incurs much human impact as a national park.

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.