THE SPATIAL STRUCTURE OF SHREW POPULATION S (SOREX, INSECTIVORA) AND ITS CORRELATION WITH THE FEED BIOMASS IN COMMUNITIES

The studies were carried out from 1986 to 1990 on the northeastern sho re of Lake Ladoga. The territorial behaviour of Eurasian common shrew (Sorex araneus L.) and S. isodon Turov was evaluated basing on live tr apping of marked animals in experimental enclosures. The distribution of common shrew depends on the biomass of soil and terrestrial inverte brates (r = 0,97). Correlation between the number of shrews (y) and th e biomass of invertebrates (x) is reflected by the equation y = 0.97x - 0.05. The territorial behaviour of overnintered females varies depen ding on their age and reproductive activity. The activity of breeding females is more restricted. The size of their home ranges reached its maximum value (up to 1600 m, average 1300 m). After the end of reprodu ctive period, the females begin to move and the structure of home rang es disappears. Overwintered males are more mobile in summer and their home ranges are somewhat larger. Home ranges of juveniles (youngs of t he year) significantly overlaps. Their mean area varies between 360 an d 500 m. At the same time, some youngs have no home ranges. S. isodon are more mobile as compared with common shrews. However, they have hom e ranges as well.