Energy and immune parameters of northern red-backed voles (<Emphasis Type="Italic">Clethrionomys rutilus</Emphasis>) at different population densities in the Kolyma River basin

Several parameters of energy and immune homeostasis in immature red-backed voles at different phases of the population cycle have been evaluated and compared over three cycles (2002–2009). It has been found that a specific morphophysiological type of population is characteristic of each phase of the cycle. The values of all physiological parameters recorded at high and low population densities significantly differ from each other, with their values being usually intermediate at a medium density. The level of most energy and immune parameters at the phase of population peak corresponds to that observed under stress. Supposedly, stress contributes to suppression of reproduction and increased mortality of the voles.