Though body weights of bears are known to change seasonally responding to nutritional conditions, there is little information on the body weight and nutritional condition of Asiatic black bears, Ursus thibetanus. We weighed seven female Japanese black bears, U. thibetanus japonicus, under captive condition from May to December, 1995. Although the body weights did not differ significantly between years, three seasonal phases were distinguishable according to the increase rate (r_w). During Phase I, mean body weight increased gradually from May (46.2±4.4 kg, mean±SD, n=6) to August (57.3±3.5 kg, n=6: 5%<r_w<10%). From August to November, the mean body weights were stable (59.4±4.3 kg, n=4: r_w<5%). Contrary, body weights increased rapidly during November and December (68.4±4.7 kg, n=5: 10%<r_w). The gradual body weight increase in the Phase I was probably because of sufficient food and lower energy expenditure, while the rapid increase in Phase III seems to be an adaptation for hibernation.

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The distribution and habitat use of the Eurasian red squirrel Sciurus vulgaris L. was studied in Nopporo Forest Park (43°20'N, 141°30'E), Hokkaido, Japan where a study area consisting of a total of 401, 200 m by 200 m, grid squares was established. Observations were made of individuals, their dreys, their feeding signs, and their footprints (after dusting with wheat flour). Squirrels were found to be widely distributed throughout the study area, and to inhabit 45 of the 401 squares (11.2%). Squirrels occurred at high frequencies in three areas within the forest. The percentages of squares in which squirrels lived, differed significantly between different forest types, with 28.2% of squares in evergreen coniferous forest used, 5.3% in deciduous coniferous forest; 5.2% in mixed forest; 3.9% in deciduous broad-leaved forest, and 0% in other areas. We concluded that dusting with flour was a useful method for revealing footprints, and that this facilitated the ease study of squirrel distribution. The distribution of the red squirrel clearly depends on the forest type. Coniferous forest areas were selected as habitat by squirrels during summer because they provided good sources of food and ideal sites for building dreys.

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Wear rates of lower first molars (M₁) in Sika deer, Cervus nippon, were compared among the increasing, declining and post-decline phases of population dynamics on Nakanoshima Island, Hokkaido, Japan, to evaluate the effects of food limitations on deer feeding ecology. Teeth specimens were collected also from a population in eastern Hokkaido, as a control, where foods were abundant. The maximum length and width of M₁ were not different among the three phases. A linear regression coefficient for log-transformed M₁ height against age was not different between males and females, but significantly smaller in the post-decline phase population than in the increasing phase and the control populations. The results suggest that M₁ wear rates increased as food declined.

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We examined the intra- and inter-specific genetic relationships of the Japanese marten Martes melampus and the sable M. zibellina using cytoplasmic and nuclear DNA markers. The interspecific sequence divergences in the 402 base pairs of the mitochondrial cytochrome b gene averaged 3.3%. The extent of the divergences among thirteen individuals of M. melampus collected from Honshu, Shikoku, Kyushu and Tsushima was small (≤0.5%), irrespective of their fur color variation. A somewhat higher degree of intra-specific variation (up to 1.3%) was observed among M. zibellina specimens, but the extent of inter-populational variation between Primorye, Russia, and Hokkaido, Japan, was not so high (minimum 0.2%), suggesting that there has been recent genetic communication between Hokkaido and the continent. Among the 24 restriction sites of the nuclear ribosomal DNA spacer, there was no difference within either species, however one site differed between the two species. Using these molecular markers we confirmed that an amimal from Hokkaido, showing the typical morphological characteristics of M. melampus, possessed the same genotype as M. melampus from Honshu. From these results and descriptions in the literature, we presumed that the animal in question could be a descendent of M. melampus introduced to Hokkaido from Honshu by fur farmers about 50 years earlier. Eight animals examined from Hokkaido showed no indication of hybridization between the two species.

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The conventional and G- and Q-banded karyotypes of the Korean red-backed vole Eothenomys regulus (2n=56) are described here for the first time. The autosomes were found to be composed of 26 pairs of acrocentrics and one pair of metacentrics, as in other species of red-backed voles. Side-by-side pair-matching analysis revealed that the G-banding patterns of E. regulus were essentially identical to those of the grey red-backed vole Clethrionomys rufocanus, and therefore the karyotype of E. regulus was of a “rufocanus” type, not of a “glareolus” type, which is characterized by 1-9 translocation. The sex chromosomes of E. regulus were found to be composed of a large subtelocentric X chromosome and a medium-sized subtelocentric Y chromosome, closely resembling those of E. smithii in both size and morphology. Both X and Y sex chromosomes were indistinguishable between these species, as far as conventional staining is concerned. Further analysis indicated, however, that E. regulus' Y chromosome has a large C-band area on the terminal half of its long arm, whereas E. smithii has a large C-band area on the proximal half of its long arm. Such C-band patterning implies the involvement of the Y chromosome in paracentric inversion during the course of speciation.

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We examined the geographic variation of Tokudaia osimensis through the analysis of mitochondria1 cytochrome b (cyt b) gene sequences and the restriction fragment length polymorphism (RFLP) in the nuclear ribosomal RNA gene (rDNA), using samples collected from Tokuno-shima and Amami-oshima in the Ryukyu Islands. The two populations show intrinsic karyological variation (Tokuno-shima, 2n=45; Amami-oshima, 2n=25). Sequences of the cyt b gene differed considerably between the two island populations. The extent of the sequence divergence among 1,140 bp of the gene was calculated to be 0.088 using the Kimura two parameter method, and was comparable to those between related species of rodents such as within genus Mus or Rattus. The extent of the differentiation in the rDNA-RFLP was also high. Three out of 22 restriction site variants were found to be fixed in the nuclear rDNA arrays of hundreds of copies in either one of the two island populations. These intensive inter-populational differences indicate that the two island populations may have been isolated for a considerable period of evolutionary time, probably several millions of years, despite there having been several opportunities for renewed genetic contact during the Pleistocene ice ages. Our data strongly suggest that the current taxonomic status of the populations of the two islands, Amami-oshima and Tokuno-shima, which regards them conspecific, should be reviewed.

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