Sorex araneus (L.) under the anthropogenic transformation of the Eastern Fennoscandia taiga forests

In the East Fennoscandia, common shrew (Sorex araneus L.) takes absolutely the first place according to the population of small mammals (1,7 ind. per 100 trap-days, and 5,6 ind. per 10 groove-days, respectively, 44,8 and 46,0 % at catches). It dominates in the most of surveyed habitats. As long-term observations (1958-2013) show, it demonstrates positive reaction to deforestation in general: the abundance of this species is on average 1,5-2 times more at harvesting areas and the young forests than at mature boreal stands. Mentioned season change of habitat is directly related to seasonal population dynamics and reproduction way. In spring and earlier summer, when population density is the lowest, animals are concentrated at the best environmental conditions. There are mixed forests, herbal pines and timbered felling. In the second half of the summer and earlier autumn shrews settle much broader, occupying almost all suitable habitats. In October and earlier November, before hibernation, shrews resettle in spruce forests, mixed and birch forests, and people’s shelters. Its number falls sharply at other habitats. Annual changes are even more clearly. During years and periods of low population animals are more demanding to the choice of habitats and prefer a few of them with the best forage and cover. On the other hand, if there is a high density of shrews, its settle widely and evenly distributed in most habitats.