Population cycles bank vole Myodes (Clethrionomys) glareolus: communication with reproductive process

On the basis of about long-term if complex observations upon numbers and demographic structure of the bank vole population. The most important factors determining launching of reproduction in winter and early spring were studied. It was shown that the phenomenon of reproduction under the snow cover is quite a common event in Udmurtia. This phenomenon seems to be more or less regular, occurring usually once in three years. Since winter reproduction is energy consuming process, then additional energy flow is needed for its success. The value of energy spending in the case of winter reproduction is equal approximately to the half of total energy expenditures for reproduction during the whole year. In the most part of cases, reproduction under the snow cover preceded the peak phase of population cycles. In the phase of depression reproduction usually started in April-May (spring reproduction). However, no rigorous links between phases of population cycles and dates of start of reproduction were discovered phases population the cycle and terms of the beginning of the reproductive period.