The food habits of the raccoon dog Nyctereutes procyonoides viverrinus were studied in a mountainous area of Honshu Island, Japan from November 1979 to October 1980. Examination of four hundred and fifty feces revealed that fruits and insects were the most important food items in the study area, and that the raccoon dog is an opportunistic forager which collects food from the ground. The raccoon dog's food habits are discussed in relation to its distribution.

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Home range size and spacing patterns of feral cats (Felis catus) were investigated and data analyzed quantitatively, to clarify the factors affecting their social organization. "Feeding groups" were identified. These consisted of male and female members which used the same garbage site mainly for feeding (Izawa et al. 1982). The spacing patterns of females showed that they defended their feeding sites from use by females of other groups. During each season mean home range size was significantly greater for males than for females. Males expanded their ranges during the females' estrous season when their mean size exceeded the predicted size based purely on metabolic requirements. Furthermore, male home range size (during the estrous season) was correlated directly with the number of females they courted. These results suggest that the mating resource, the number of receptive females, is more important in determining male home range size during the estrous season than is the food resource.

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Habitat use and selection of the Siberian weasel Mustela sibirica during the non-mating season were studied, on the small island of Aoshima, Japan, from 1982 to 1989. Weasels occurred throughout the island. The village area was compared with the northern grassland which was less affected by human activity. Weasels in the village area were divided into two groups; the "border weasels", which had their ranges around the periphery of the village, and the "central weasels", which occupied the center of the village. The population density was lower in the grassland area than in the village. The body weight of border weasels was the largest on Aoshima. Border weasels rested in barns and houses and were active in grasslands and on roads, while weasels in the grassland rested and were active mainly in grasslands. Weasels frequently used piles of hay in barns as resting sites in the village. Resting sites, offering good thermal conditions, are thought to be important factors of the range of the Siberian weasel, especially for females, during winter. The village periphery was assumed to be the most favorable weasel habitat because the village area provided good resting sites and a wide range of food.

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Techniques for DNA extraction from small pieces of animal tissues and for polymerase chain reaction product-direct sequencing have been improved for molecular phylogenetic study. Using the techniques, the cytochrome b genes (375 bases) in the mitochondrial DNA were sequenced for three species of weasels distributed in Japan: Mustela itatsi, M. sibirica, and M. nivalis. M. itatsi and M. sibirica were identified by means of the ratio of the tail length to the head and body lengths. Five specimens of M. itatsi (a native Japanese species) showed 4.0-4.3% difference of the nucleotide sequence (15-16/375 bases) from two individuals of M. sibirica (a species introduced to Japan from Korea). A phylogenetic tree, constructed using sequence data, suggests that M. itatsi is distinct from M. sibirica in agreement with its morphological characters. M. nivalis was more distinct with a 6.4-6.9% sequence difference from the other two species. On the basis of nucleotide substitutions, the divergences of M. itatsi from M. sibirica and M. nivalis are estimated to have occurred around 1.6-1.7 million years ago and 2.7-2.8 million years ago, respectively. Thus, cytochrome b sequence analysis with the present improved methods provides a new clue for the development of the phylogenetic study of closely related mammalian species.

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Social grouping patterns of Japanese wild boar Sus scrofa leucomystax were studied, by direct observation on a population in the Rokko Mountains of western Japan, from April 1982 to July 1988. We observed identified individuals for 2404 hours over 1323 days. Social groups were classified according to their composition. There were three recognized age categories: adults (≥2 years old), juveniles (1 year old), and infants (<1 year old). Eleven types of social group were recognized in the population there, however, adult males were always solitary, and the basic family group (a mother with her infants or juveniles) was the most frequent social group involving adult females. Since the basic family group contains only one adult (a mother), it is concluded that both male and female adult Japanese wild boar in our population were basically solitary. Continuous observation of various social groups revealed that group formations changed throughout the year in relation to the timing of farrowing and the timing of male's independence for solitary life.

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Mammalian remains from 24 Jomon Period sites in Kagoshima Prefecture, Kyushu, Japan, were taxonomically and quantitatively analyzed. Twenty five mammal forms belonging to 10 orders were identified: Mogera wogura, Pteropus dasymallus, Macaca fuscata, Lepus brachyurus, Pentalagus furnessi, Petaurista leucogenys, Muridae gen. et sp. indet., Cetacea fam. gen. et sp. indet., Delphinidae gen. et sp. indet., Selenarctos thibetanus, Canis lupus, Canis familiaris, Nyctereutes procyonoides, Meles meles, Lutra lutra, Martes melampus, Mustela sibirica, Lynx lynx, Zalophus sp., Dugonidae gen. et sp. indet., Equus caballus, Sus scrofa, Cervus nippon, Capricornis crispus and Bos taurus. Of these, Canis lupus, Selenarctos tibetanus, Lynx lynx and Lutra lutra were extremely rare at Jomon sites in Kyushu. Sus scrofa and Cervus nippon were dominant, contributing 92% of the total bone fragments. In the Amami Shoto Islands, eight mammal forms, fewer than in mainland Kagoshima, were detected. It is assumed that by the Jomon Period (ca. 2500-300 BC), the faunas in north and south of the Tokara Strait (Watase's line) in Kagoshima Prefecture had already differentiated.

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