The habitat preferences of small rodents was investigated in natural deciduous forests of Pyongchang, Kwangwon Province, South Korea from May to November 1996. Three sites (one hectare each) were selected as cutting, thinning, and control. A total of 142 small rodents were captured using live traps in the three sites: 64 (45.1%) Korean field mice Apodemus peninsulae and 78 (54.9%) Korean large-toothed red backed voles Eothenomys regulus. The number of small rodents captured was highest in the control site and lowest in the cutting site. Differences in habitat preferences were found between the two species. Apodemus peninsulae was captured only in the cutting and the control site, while E. regulus was found only in the thinning and the control site. Apodemus peninsulae were mainly captured near woody debris and piles of stones in the cutting and control sites. In the thinning site, however, there was little woody debris and few piles of stones were available, and these two may be critical factors affecting the distribution of A. peninsulae. In contrast, tree density, tree species diversity, and the depth of the litter layer are the major factors affecting the distribution of E. regulus.

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In Japan, sika deer (Cervus nippon) feed on bark and consequently damage sugi (Cryptomeria japonica), a common plantation tree species. We investigated factors that might explain variability in the extent of damage in northern Honshu. The percentage of damaged trees varied widely, even among adjacent plantations, suggesting that the factors affecting the degree of damage operate at a local level. The percentage of damaged trees was not correlated with either the age of stands or the forage biomass of the plantations, and was only weakly correlated with the density of deer fecal pellets, although the sites examined were biased toward a low density. Other factors such as forage biomass within the broader home range may influence deer use of sugi plantations.

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Thirty-eight museum specimens of the Ryukyu spiny rat, belonging to the genus Tokudaia Kuroda, 1943 (Rodentia, Muridae), from the islands of Amami Oshima and Okinawa, in the Ryukyu Islands (=the Nansei Islands), southern Japan, were examined and measured. Each specimen was classified into one of five age groups (I-V) determined by the wear of the three upper molars. The spiny rat of Okinawa has on average within age groups III and IV a statistically longer and wider skull and a longer molar row than that of Amami Oshima. However, neither the posterior nor the central parts of the skull length and width differ between the two islands. Against the same size of head and body length (H&BL) or incisor - the third upper molar length (I-M3), the spiny rat of Okinawa has longer I-M3 or narrower zygomatic arches than the spiny rat of Amami Oshima. The Okinawan spiny rat has a wider first upper molar (wM1≥1.9 mm), whereas that of Amami Oshima is wM1≤1.8 mm. The Okinawan spiny rat has the palatine foramen of the skull situated more posteriorly than that of Amami Oshima. These findings indicate conclusively that the spiny rat populations on the two islands of Amami Oshima and Okinawa have distinctly different morphological characteristics, in addition to having different karyotypes, and as such they should be regarded as distinct species. The spiny rat of Amami Oshima should be named as Tokudaia osimensis (Abe, 1933) while that of Okinawa should be known as Tokudaia muenninki (Johnson, 1946).

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Two species of moles, Mogera tokudae and M. imaizumii, are parapatrically distributed in the Echigo Plain in the northern part of Niigata Prefecture, Japan. The two species are morphologically similar, except for the larger body size of M. tokudae. To clarify whether interspecific competition affects body size and reproductive traits of these moles, we compared these characteristics in syntopic populations with those in allopatric populations for both species in the Echigo Plain. Mogera tokudae exhibited little body size difference between allopatric and syntopic populations, while body size of M. imaizumii in syntopic populations was significantly smaller than in allopatric populations. Although litter sizes of both species were almost the same, reproductive schedules were different. Pregnant M. tokudae were captured mostly in late April, whereas M. imaizumii had a longer period of reproduction from March to October; some individuals bred twice a year. The relatively small body size and the longer breeding period observed in M. imaizumii of the Echigo Plain may be tactics for increasing reproductive success under severe interspecific competition from M. tokudae.

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A large dominant mole species, Mogera wogura, is progressively expanding its range northwards, displacing a small inferior species, M. imaizumii, in Honshu, Japan. Three of the boundaries where the ranges of the two species abut have been found in the Agematsu region, in the Kitaono region of Shiojiri City, and in the Tatsuno-Suwa region of Nagano Prefecture, central Honshu. The range expansion of M. wogura, however, has been blocked in some areas for long periods. I investigated soil hardness, as one possible factor affecting mole distribution, in habitats on both sides of the boundaries where M. wogura's range expansion has been halted. This investigation clearly revealed that where soft (< 10 kg⁄cm²) soil layers are retained to depths of about 60 cm, or where deep (about 60 cm) soft soil occurs over more than half of the area, M. wogura is able to displace M. imaizumii. In areas where soft soils were shallower than about 60 cm, M. imaizumii was able to continue to inhabit the contact zone, thus soil hardness appears to be an important factor limiting the range expansion of M. wogura.

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The stomach of a newborn pygmy hippopotamus (Choeropsis liberiensis) was examined by means of gross anatomy and light microscopic histology. Numerous papillae were observed on the inner surface of the diverticulum and forestomach, and reddish, smooth, and moist lamina were apparent in the posterior stomach. Histological sections revealed a keratinized squamous epithelium covering the entire inner surface of the diverticulum and forestomach. In the posterior stomach, the epithelium and lamina propria were composed of many papillae. Specific gastric glands containing chief and parietal cells occupied the lamina propria in the posterior stomach, however, the cardiac and pyloric glandular regions could not be observed in any section. Although the sample material was excised from the carcass of a newborn, we can conclude that the diverticulum and forestomach are morphologically similar to the rumen, reticulum or omasum in ruminants, whereas the posterior stomach functionally accords with the abomasum. The diverticulum and the forestomach may act as a fermentation tank and dehydration apparatus, respectively, for stomach contents, and the posterior stomach may function as the secretion system for gastric juices.

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The homologies of the carpal bones of flying squirrels, presented by Oshida et al. (2000a, b), are reviewed, together with the evidence supporting traditional homology assessments. Evidence for the homology of the styliform cartilage of flying squirrels with the hypothenar cartilage of other squirrels is also reviewed. Development, articulations, topography, and muscle insertions favor both the traditional hypothesis of homology assessments of the carpal bones and also the hypothesis that the styliform cartilage is homologous with the hypothenar cartilage.

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