著者

宮尾 嶽雄 両角 徹郎 両角 源美 花村 肇 佐藤 信吉 赤羽 啓栄 酒井 秋男

出版者

社団法人日本動物学会

雑誌

動物学雑誌 (ISSN:00445118)

巻号頁・発行日

vol.72, no.7, pp.187-193, 1963-07-15

被引用文献数

6

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The authors investigated the seasonal differences of sex ratio, body weight, percentage of pregnant female and testicle size in two species of the field mice, Apodemus argenteus and Clethrionomys andersoni, collected from April, 1962 to March, 1963, in the subalpine forestzone (Tsuga diversifolia-Abies Mariesii forest zone, alt. 1,800-2,400m) on Mt. Yatsugatake in Honshu. Toral number of collected specimens was 308 Apodemus ar genteus and 616 Clethrionomys andersoni. 1) The number of males was larger than that of females in all months except August in Clethrionomys andersoni (♀ 56.7%), and July in Apodemus argenteus (♀ 54.6%), during the height of the breeding season (Fig. 1). 2) From the histograms of the body weight, the following tendencies were noted. Young mice appeared from July to October in Clethrionomys andersoni, and from June to September in Apodemus argenteus. Old adults disappeared from November to March in Clethrionomys andersoni, and from August in Apodemus argenteus. In both species, the developmental period of body weight generally coincided with the spring breeding season (Fig. 2 and Fig. 3). The life span of these species was supposed at about 1 year. 3) The maximum monthly pregnancy rate was attained in June in both species (Fig. 4). The yearly average embryo size was 3.3 in Clethrionomys andersoni and 3.9 in Apodemys argenteus. 4) The monthly average testicle sizes were about 10 mm. from April to July in both species. But they were about 4 mm. from October to March (Fig. 5).

著者

宮尾 嶽雄 両角 徹郎 両角 源美 花村 肇 佐藤 信吉 赤羽 啓栄 酒井 秋男

出版者

日本動物学会

雑誌

動物学雑誌 (ISSN:00445118)

巻号頁・発行日

vol.72, no.5, pp.133-138, 1963-05

被引用文献数

4

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From April, 1962 to March, 1963, the authors collected small mammals (Rodentia and Insectivora) monthly by snap traps in the subalpine forest zone (Tsugadiversiforia-Abies Mariesii forest zone, alt. 1,300-2,400m) on Mt. Yatsugatake in Honshu. Total number of captured mice and voles was 961 with the following proportional breakdown: Rattus rattus 1, Apodemus speciosus 14, Apodemus argenteus 308, Clethrionomys andersoni 616, Anteliomys smithii 20, Microtus montebelli 2. The number of moles and shrews taken was 231 with the following breakdown: Euroscaptor mizura 1, Urotrichus talpoides hondonis 18, Dymecodon pilirostris 151, and Sorex shinto shinto 61. Rattus rattus and Microtus montebelli were found in this area. Apodemus speciosus and Urotrichus talpoides hondonis were only found in the lower part of this grassy area. On the other hand, Apodemus argenteus, Clethrionomys andersoni, Anteliomys smithii, Dymecodon pilirostris, Sorex shinto shinto were widely found in this forest zone. It was noted that the largest number of Apodemus argenteus appeared in spring, but the peak of Clethrionomys andersoni was seen from autumn to winter (Fig. 2). The average embryo sizes of each species were as follows: Apodemus speciosus 5.7, Apodemus argenteus 3.9, Clethrionomys andersoni 3.3, Anteliomys smithii 3.5, Microtus montebelli 3.0, Urotrichus talpoides hondonis 4.5, Dymecodon pilirostris 3.5, Sorex shinto shinto 3.7. The highest capture rate (number of captured small mammals/no. of set traps) occurred in October and the lowest rate in February. They reflect the effect of the population density and the snow fall, etc.