Relationships between Shrews (Sorex, Eulipotyphla) and Ground Invertebrates on the Northern Coast of the Sea of Okhotsk

To assess the influence of the trophic factor on the survival and abundance of shrews in the conditions of the Far North, the relationships between their population dynamics and the abundance of ground invertebrates were analyzed. The studies were conducted in typical (a larch forest on the lower part of a mountain slope) and intrazonal (a floodplain chosenia forest) habitats on the northern coast of the Sea of Okhotsk. The relative biomass of invertebrates (according to pitfall trap counts) at the end of the summer period shows an inverse relationship with the number of shrews, which may indicate a significant impact of these insectivores on food resources in years of their high abundance. The number of overwintered shrews in a typical forest habitat was positively correlated with the relative biomass of invertebrates at the end of the previous summer. In the intrazonal floodplain habitat, no significant relationship was found between the number of overwintered animals and the previous biomass of invertebrates, but due to floods and aufeis, the chosenia forest is unsuitable for small mammals in the cold season. The results of the study suggest a fairly high interdependence between the dynamics of the abundance of shrews and their food items in relatively unproductive northern ecosystems.