Materials for the study of the ecology of the common shrew (Sorex caecutiens Laxm.) in the European part of its range. Message 1. Abundance and biotopic distribution

This report presents an analysis of the population-ecological characteristics of the masked shrew that lives on the European periphery of the range. It is based on the materials of long-term (1958-2018) stationary and expeditionary studies covering Karelia and the adjacent regions of Eastern Fennoscandia. It was found that under these conditions, this species is characterized by a generally low abundance level compared to Siberian populations: 0.07-1.3 ind. for 100 trap-days and 1.4-2.5 ind. for 10 ditch-days, ranking third in number after the common and small shrews. In northern Karelia, it averages 0.3 ind. for 100 trap-days (5.1 % in the catches of small mammals), 0.7 (4.9 %) in the middle Karelia, and 0.07 (1.7 %) in the southern Karelia. In total catches by ditches, shrews of this species accounted for 7.7 % of the total number of small mammals caught, and in catches of Soricidae - 9.4 % (1.07 ind. per 10 ditch-days). The average indicator for the region is 0.35 ind. per 100 trap-days. In Eastern Fennoscandia (including eastern Finland), the common shrew is a widespread species but having a small number. At the same time, it is here one of the few species of small mammals that most painfully react to the removal of the maternal canopy of mature coniferous stands. In Siberia, the masked shrew is the most typical species of shrews, dominating in most forest biotopes. In the conditions of the European part of the range, as well as in Siberia, the masced shrew is a fairly wide eurytope, but it manifests a clear attraction to cluttered grass-green-moss pine forests with an admixture of hardwoods and spruce, confined to flat landscapes with average moisture and a thick layer of forest litter. Here, in the biocenotic groups of local mammals, it, as a rule, occupies the fifth place in terms of abundance, yielding in this indicator to the common and small shrews and red-backed and field voles.