小林地におけるエゾアカネズミの個体数,活動量,活動域の季節的変化

概要

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Seasonal fluctuations of population size, activity and activity area of <I>Apodemus speciosus ainu</I> THOMAS were studied by live trapping method in a small stand (0.33ha) of broad-leaved trees, which located in Osatsu, Chitose city, Hokkaido, from April, 1978 to September, 1979.<BR>This species has been reported never to be abundant in Hokkaido, but it was the most dominant species (90%) in the stand. The density of over-wintered population in spring was 30/ha, and density become 90/ha in autumn. The population drastically increased according to the appearance of young in May and June, and then gradually decreased till November. During the one month before snow fall, however it was greatly decreased. Relatively high survival rate (76%) was observed in winter (5 months), and this over-wintered population was slightly decreased before the appearance of young.<BR>In over-wintering and reproductive periods, the activity area of this species was limited within this stand, but it was extended to the surrounding grasslands thereafter. The activity area in this stand was seasonaly changed with relation to plant cover. The activity of mice was indicated by a capture rate and a mean distance of movement. Both the values were significantly small in December, and almost zero in February. The least activities and high survival rate of this species under snow cover might have some relations to its large stock of seed cashe.