[Structure of the bank vole (Myodes glareolus) population cycles in the center and periphery of its distribution area].

The results of long-term studies of two bank vole (Myodes glareolus) populations in stationary sites in the central part and periphery of its distribution area are described. Four phases of a multiannual population cycle and two of its structural parts have been detected for both populations. The first part of the cycle is "determined", with the "peak" phase passing into a "depression" (population collapse). This transition is mainly "determined" by intrapopulation processes and is weakly dependent on the external conditions of each individual year. The second part is "stochastic", starting from a stable point in the cycle in the "depression" phase. The duration of the second part is determined by the state of the population and its ability to increase its size, as well as by the weather and food factors, predation pressure, and location of the population within the distribution area. The transition from the "peak" phase to the "depression" phase (the "determined" part) for both populations takes place during one fall-winter-spring season and has no effect on the cycle duration. The duration of the stochastic part in the center of the distribution area (the period from "depression" phase to "peak" phase) is 1-3 years and in the periphery, 2-4 years.