Some physiological and biochemical parameters of underyearling Laxmann’s shrews (Sorex cecutiens Laxmann) and even-toothed shrews (Sorex isodon Turov) under different population densities

Based on the results of a study conducted in the Buyunda River basin (tributary of the Kolyma River) in 2006–2010, influence of the population density of shrews (Sorex) on some physiological and biochemical parameters (glycogen and lipids in the liver, relative weight of the spleen, white and brown adipose tissue, cellularity of bone marrow) was investigated. The content of energy reserve substances was found to be closely connected with the number of animals (fat deposits had inverse relation; glycogen content in the liver had direct relation). Other physiological-biochemical parameters had no significant relation to the population density, although such tendency was observed for the content of brown fat and cellularity of bone marrow tissue in Sorex isodon, and for the relative weight of the spleen in both species of shrews. We suggest that the identified physiological changes indicate irregular feeding of animals in years with higher population densities.