ヒミズの繁殖活動〔英文〕

概要

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1. Reproductive activity of the Japanese shrew-mole, Urotrichus talpoides, was investigated by mark-release and removal methods in the University Forest in Chiba, University of Tokyo from April 1975 to July 1979. One livetrapping plot (L plot) and several snap-trapping lines (S lines) were set up in the mixed forest. 2. The testis length of sexually active males was more than five mm, and the weight of active males mostly exceeded 14g. Breeding females were usually heavier than 13g. 3. Males became sexually mature in early February, and in May, active males rapidly decreased. Matured females were mainly observed in February and March, pregnant females, in March and April, lactating females, in April and May. The current year's young became captured in April, and did not attain sexual maturity until the following spring. These seasonal changes of reproductive phase were relatively constant from year to year. 4. On L plot, the percentage of active males to the total adult males reached 100 every year during the study period, and among resident adult females, the percentage of lactating individuals was 83.3-100.0. 5. Estimating from the results of live-trapping, gestation, lactation and the period from parturition to independence of the young were all about four weeks. 6. The mean litter size was 3.6 (N=8) .
日本哺乳類学会の論文