北海道石狩防風林のエゾヤチネズミの個体群構成と繁殖活動

概要

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Seven hundred and sixty four voles (<I>Clethrionomys rufocanus bedfor-diae</I>) were collected in a wind shelter-belt of the Ishikari Plain, Hokkaido, during May to November, 1966 and 1967 and the population structure, reproductive activity and number of embryos were investigated. The proportion of overwintered males was much less than that of females, and almost all the overwintered individuals remained mature through the breeding season. Only young born early in the breeding season grew to sexual maturity in the season. Sex ratio of all young was even, but matured young males were much less than matured young females. Main breeding season was May to September with a peak in July. No fall breeding was observed in both the years. It was suggested that maturing of young females was affected by the existence of matured overwintered females. Features of breeding activity indicated those as in the peak phase of population as so far known. Nine to 12 months old females which were pregnant in early season before June had significantly larger litter than did those in later season after July.
日本哺乳類学会の論文