Зоологический журнал

Dynamics of the numbers and altitudinal distribution of Clethrionomys rutilus (Rodentia, Cricetidae) in the Western Sayan

Zhigalsky O.A., Naumov R.L., Zharikova E.N.

An analysis of dynamics of the northern red-backed vole numbers and distribution has been carried out on the basis of many years' observations (from 1965 to 1983) in the Western Sayan on the territory of about 25 km2 in the mountain taiga belt with differences of altitudes from 600 up to 1,400 m above sea level. On the basis of the whole complex of population characteristics the whole territory occupied by the northern red-backed vole is divided into two regions, that is a region of optimal conditions for habitation (the numbers are maximal, its variability is minimal, the degree of animal involvement in reproduction is maximal) and a region of pessimal conditions (the numbers are always lower, their variability is high, only a small part of animals are involved in reproduction). Since the fluctuations in the numbers are synchronous in both of the regions, there are good reasons for considering all the animals on the territory examined (about 25 km2) as a single population of the northern red-backed vole.