西中国山地におけるツキノワグマ(Selenarctos thibetanus japonicus)の分布量動向と植生変化

抄録

The Japanese black bear (Selenarctos thibetanus japonicus) is a representative large wild mammal which has had close relations with the life of the Japanese. The animal has been an object of hunting from ancient times, because it is believed to have certain medicinal value. However, few studies have been done on the ecology of the Japanese black bear, or on its habitat distribution, both of which may be much affected by changes in man's life style.
The purpose of this study is to ascertain primarily changes in the distribution of the Japanese black bear in the West Chugoku Mountains since the Taisho era (1912_??_1926). The location, which remained uninvestigated until this study, marks the western fringe of the animal's habitat in Japan. The findings are as follows:
1) From the Taisho era to early Showa (1926_??_1944), the Japanese black bear maintained its habitat in virgin broadleaf deciduous forests containing beeches (Fagus crenata Blume), horse chestnuts (Aesculus turbinata Blume), varieties of Japanese oaks (Quercus mongolica Fischer var. grosseserrata Rehd, et Wils; Quercus serrata Thunb), etc. Such forests supplied Japanese black bear's food (nuts, berries, buds, leaves, stalks, etc.) as well as provided tree hollows for hibernation. Thus, the bears seldom appeared in villages. At that time, the Japanese black bear commanded good prices mainly as material for medicine, and its hunting constituted one of the important side jobs in the winter season.
2) From around 1960, the virgin broadleaf deciduous trees have been replaced by Japanese cedar trees (Cryptomeria japonica D. Don) through afforestation. As a result, Japanese black bears, losing source of food and places for hibernation, have been driven out of their former habitat. They have thus started to hibernate in the vicinity of villages, or damaging crops and becoming a nuisance to the villagers. After World War II, hunting for Japanese black bears has declined due to the increased availability of synthetic medicine, but in contrast hunting for ellmination has increased.