木曽駒ケ岳の哺乳動物に関する研究-1-木曽駒ケ岳東斜面における小哺乳類の分布 Studies on Mammals of the Mt. Kiso-Komagatake, Central Japan Alps. I. Distribution of Small Mammals on Eastern Slope of the Kiso-Komagatake.
The Kiso-Komagatake is one of the main mountains in Kiso Mountain Range, which rises nearly on the middle of Japan main land, that is, on the western side of the Ina Basin in Nagano Prefecture, forming the watershed between the Rivers Kiso and Tenryu. The highest summit is as high as 2,956m above the sea level. One can in a while attain the height of 2,500m above the sea level from the City Komagane (600m high) by means of bus and then ropeway and many tourists visit the mountain throughout the year. This, together with extensive amount of wood cutting, has contributed to the rapid deterioration of the nature. As for the botanical distribution of the mountain, Pinus pumila is predominant in the alpine zone, higher than 2,500m above the sea level, Abies mariesii and Tsuga diversifolia in the sub-alpine zone, 1,500-2,500m high, and Quercus crispula in the lower zone, lower than 1,500m. Cultivated lands and village can be found in the zone lower than 900m above the sea level. The natural flora is confined to the subalpine zone and the lower zone is mostly occupied by the secondary forest, mainly consisted of Larix kaempferi. To obtain the general distribution of small mammals on eastern slope of the Kiso-Komagatake, the authors have carried out the collection and survey since June 1974. The results are as follows : 1) The collection was made with snap traps at 6 places of different height, ranging 950-2,640m above the sea level on the eastern slope, and the following species were obtained : Insectivora Sorex shinto alt. 1,500-2,640m Crocidura dsinezumi alt. 1,200m Dymecodon pilirostris alt. 1,300-1,700m Urotrichus talpoides alt. below 1,300m Rodentia Glirulus japonicus alt, 1,700m and 1,300m Clethrionomys andersoni alt. 1,300-2,640m Eothenomys kageus alt. 1,200-1,500m Microtus montebelli alt, below 1,200m Apodemus speciosus alt. 950-1,500m Apodemus argenteus alt. 950-2,640m Rattus norvegicus alt. 2,640m around the ropeway station, hotel and restaurant in the alpine zone. The widest distribution was shown by A. argenteus, being found at any place in the altitude of 950-2,640m. The species which was distributed from the sub-alpine to alpine zone was S. shinto and C. andersoni. D. pilirostris was native to the forest of sub-alpine zone. C. andersoni and E. kageus are both forest dwellers, the former species is used to live in above 1,300m and the latter live in below it. The distribution border between D. pilirostris and U. talpoides was also at the altitude of about 1,300m. M. montebelli generally inhabits in cultured land, grassy plain and young forested land. In the Kiso-Komagatake, however, this species did not distribute in higher altitude than 1,300m even when the habitat was sufficient. This is probably because of very steep slope of the mountain side. R. norvegicus inhabited around the ropeway station, hotel and restaurant in the alpine zone, propagating themselves even in very severe cold conditions. The higher the altitude of the population of A. argenteus, the later the beginning of propagation in spring occured. 2) In the zone, ranging 1,300-1,500m above the sea level, small mammals were caught with snap traps in three Larix kaempferi-afforested lands of different age and the relation between forest age and species of small mammals was examined. A. speciosus was found in the sapling and the young forest but not in the grown forest, while a large amount of A. argenteus was found in the grown forest according to Apodemus Index. C. andersoni was not found in the sapling, while E. hageus was relatively large amounts in the sapling and the young forest, though absence in the grown forest. 3) In a few Larix kaempferi forest in the altitude of 1,300m, movements of A. speciosus and A. argenteus were followed up for 7 days by the use of alive traps. The distance of two traps which caught the same individual in two consecutive nights was measured with the following results :In case of A. speciosus, it was 11.3m (mean for 5 cases) in June and 21.0m (mean for 4 cases) in August. The mean for June and August was 15.6m for 9 cases. In case of A. argenteus, the mean distance in June was 15. 5m for 7 cases. From these figures, the diameter of the home range was calculated, with the result that the mean was 33.1m for A. speciosus and 27.8m for A. argenteus. There was little difference between them.
信州大学農学部紀要 12(2), p61-91, 1975-12