トウホクノウサギの生態に関する研究 : 1.繁殖について

概要

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A number of the so-called Tohoku hare, Lepus brachyurus angustidens HOLLISTER were collected in the mountain of Yamagata Prefecture from. May, 1962 to September, 1964 in order to determine the breeding season, litter size and ovarian weight. The observation was made on 136 specimens. The results are as follows : 1) The gestation period of the animal extended from February to July and the young were born between April and August, being more frequent in May and June than in the other months. The average litter size was larger in the month in which the highest rate of birth occurred than in the other months. 2) The female matured sexually in about ten months after birth. Therefore, the frst breeding season came next year. 3) The average number of embryo found in the uterus was l.85 in 12 pregnant females and the lavgest number was 3. The number of the young in one birth was ordinarily 1 or 2 but sometimes 3. 4) The average litter size observed from the number of the captured young in the feld was 1.86 and the largest litter size was 4. The litter size was the largest in May, being 2.50. 5) The weight of the ovary of both sides in the same female was almost equal. There was no difference of the ovarian weight between the uterine side with the fetus and the side without fetus. 6) The ovarian weight increased suddenly to 400mg in February. The smallest ovarian weight of the pregnant female was 470mg.
日本応用動物昆虫学会の論文
1965-06-25