Habitat variables of the Japanese squirrel, Sciurus lis Temminck, were analyzed by the regression tree method based on radio-tracking data. The results suggest that the squirrels tended to use the sites with more walnut trees from July to December, and more evergreen trees in middle layer from January to June for feeding. For nest sites, they tend to use sites with more evergreen trees in the upper layer, preferably having DBH (diameter at breast height) of at least 30 cm. These results are consistent with observations in previous field studies.

抄録全体を表示

Food habits of the raccoon dog (Nyctereutes orocyonoides) at a western suburb of Tokyo were analyzed by the point-frame method by use of 344 fecal samples for a year. The food habits were omnivorous, but plants, particularly plant leaves and seeds, were predominant. The seasonal foods were characterized by leaves and flowers in spring, insects in summer, seeds in autumn, and birds/mammals and artificial foods in winter. Dependency on artificial foods was not strong. The raccoon dogs fed on various fruits and nuts, among which those of planted fruit trees like ginkgo and persimmon were particularly important. The raccoon dog seems to have adapted themselves to "satoyama", a traditional Japanese landscape.

抄録全体を表示

The reliability of body condition indicators for the Antarctic minke whale Balaenoptera bonaerensis was examined. Samples were collected from the Antarctic Ocean south of 60°S and 70°E to 170°W in austral summer by the Japanese Whale Research Program under Special Permit in the Antarctic (JARPA). As body condition indicators, blubber thicknesses, girths, LMD-indices (√body length / body weight × blubber thickness), d/r-ratios (blubber thickness/surface body radius), BW/BL³ (Body weight/body length³) and G/BL (Girth/Body length) were used. Blubber was thicker in the posterior than in the anterior of the body and thickest in the dorsal and ventral region near the fluke. The blubber in the mid part of the body was similar in thickness through ventral to dorsal region without just ahead of dorsal fin. The results showed that the medial lateral blubber thicknesses and d/r-ratios were highly correlated with total blubber mass (%sculp) and date, showing that these were simple and suitable body condition indicators for the Antarctic minke whale. In addition, the precise formulae for estimating the weight of the Antarctic minke whales (r² > 0.85) were derived using body length and a girth.

抄録全体を表示

Nucleotide sequences of sika deer (Cervus nippon) collected from the eastern part of Shikoku Island were investigated & compared with those from other areas. Nucleotide sequence of the whole D-loop region of the mitochondrial DNA was determined by direct sequencing technique for each sample. The phylogenetic tree constructed by the sequences indicates that sika deer from Shikoku Island are divided into two distinct lineages: the northern Japan group and the southern Japan group. Proportion of the northern Japan lineage was higher in the northeastern part of the sampling area. There was no border between the distribution of the two lineages, rather it seemed that their distribution intermingled. Besides, there were locations where both lineages were found within a small area. These results indicate that two lineages might be hybridized in some areas of eastern Shikoku.

抄録全体を表示

Morphological variation was examined in large Japanese field mice, Apodemus speciosus, of five populations from the Izu Islands (from Oshima, Shikinejima, Niijima, Kozushima and Miyakejima), four from the Oki Islands (from Dogo, Nishinoshima, Nakanoshima and Chiburijima), and four from the Japanese mainland of Honshu. Univariate and multivariate (PCA) analyses were conducted on the basis of body-, mandible-, and molar-measurements. Overall, the insular mice had a tendency toward gigantism, and also showed marked morphological differentiation among the islands. The sizes of the mandible and molar were inversely correlated to island area and temperature, thus suggesting a selective effect. Although faunal diversity might be related to the morphological variation in size, there was no clear relationship between the morphological variation and biotic factors such as predation and competition. The populations from the Izu Islands underwent marked morphological divergence, suggesting founder effects. The Izu Island are oceanic and have probably never been connected with Honshu, hence mice were likely transported from Honshu. On the other hand, the Oki Islands had been connected with Honshu in the late Pleistocene. The founders of the insular mice related to the history of the islands could have likely affected the morphological variation.

抄録全体を表示

A rare case of the dental anomaly, viz., intranasal tooth was observed in a female Japanese macaque monkey (Macaca fuscata) (K-105) from Kinkazan Island, Miyagi Prefecture in northeastern Japan. Intranasal tooth is an ectopic tooth erupted into the nasal cavity. The intranasal tooth of K-105 is a left P⁴ based on the morphology, and is not a supernumerary tooth. Intranasal tooth is one symptom, but, its etiology may be divided into two; one is the problem of tooth germ's development that causes intranasal teeth as supernumerary teeth, and another is the problem of tooth germ's migration that causes intranasal teeth as missing teeth from the dentition. In our sample, the tooth germ of the left P⁴ probably moved from the normal position to the nasal floor in an early life stage and developed there. The crown proportion is different from the typical P⁴ in the Kinkazan specimens. K-105 has relatively short buccolingual breadths of P⁴ on both sides. The intranasal tooth may have been an obstacle to breathing to some extent, yet K-105 survived until adulthood. The disadvantage of having an intranasal tooth in this case was not serious.

抄録全体を表示

A new species of Ryukyu spiny rat, Tokudaia tokunoshimensis was described in the specimens originating from Tokunoshima Island in the southernmost region of Japan. The populations of Tokudaia are separately distributed only in Amami-Oshima, Tokunoshima, and Okinawa-jima Islands. We have described the osteological and external morphological characteristics and clarified the osteometrical distinctions among the three populations using the skull and skin collections. All external dimensions of head and body length, tail length, hindfoot length and ear length were larger in the Tokunoshima population than in the other two in mean value. The raw osteometrical data separated the Tokunoshima Island population from the other two in all measurements except for the length of molar row in the Okinawa-jima Island population. The principal component analysis also demonstrated that the skulls from the Tokunoshima Island population were morphologically distinct from those of the other populations. Here, from these findings, we point out that the Tokunoshima population of Tokudaia should be regarded as an independent species from the two other populations.

抄録全体を表示