エゾヤチネズミの繁殖活動 : 4.胎児数と出生前死亡

概要

論文の詳細を見る
Variations in the number of embryos of Clethrionomys rufocanus bedfordiae were examined using 747 pregnant females obtained from various areas of Hokkaido in 1967-1974. The number of embryos per pregnant female ranged from 1 to 10 and averaged 5.3. The mean was smaller than that in high latitudes of the Eurasian Continent. However, regional variation was not recognized within Hokkaido. The mean number of embryos was 5.9 in June, 4.8 in August and 5.2 in October. The number of embryos tended to increase with advanced age and increased body weight of females, but it decreased in females of 12 months old. Thus the decline in the number of embryos in August and October was attributed to advanced age in overwintered females and recruitment of young females to the population. There was no difference in the number of embryos between primiparous females and multiparous ones. The number of corpora lutea per pregnant female ranged from 2 to 14 and averaged 6.1. Prenatal loss of embryos was found in 36.0% of the 439 pregnant females examined. The prenatal mortality was 9.0% for overwintered females and 16.5% for females of the year, and it increased with the increasing number of corpora lutea.
日本生態学会の論文
1981-09-30