Community Structure of the Shrews ( Sorex , Eulipotyphla) in the Seimchan–Buyunda Depression, Basin of the Upper Reaches of the Kolyma River

The Seimchan–Buyunda Depression in the basin of the upper reaches of Kolyma River is distinguished by a number of natural and climatic features: the presence of an extensive ground-filtration talik, rich vegetation of the valley forest complex, and relatively high summer temperatures. The structure of shrew community in the Seimchan–Buyunda Depression also differs significantly from that of the adjacent territories. With an obvious dominance of Sorex caecutiens , S. isodon stably occupies a subdominant position there. Within the Okhotsk–Kolyma region, such a high proportion of S. isodon in the shrew community is more typical of northern Cisokhotia. Thus, the Seimchan–Buyunda Depression is a kind of “oasis” for the species that must have entered the Upper Kolyma River from the Sea of Okhotsk coast.