Regeneration of steppe vegetation and outbreak of the social vole, Microtus socialis (Critecitidae, Rodentia), in the southwestern Chernye Zemli of Kalmykia [Russian]

摘要

The restoration of steppe vegetation in Chemye Zemli (Kalmykia) due to reducing the impact of livestock and changes in the sea level has been observed since 1994. The demographic and socilal structure and reproductive activity of various age and sexual groups of social votes depending on their numbers and foraging coditions in biotopes during the outbreak in 1997 in southwestern Kalmykia are considered. The last outbreak of the social votes was registered 30 years ago when Microtus socialis inhamited almost all the biotopes after spring reproduction. Under high levels of their numbers (above 60 animals per 100 traps) the demographic structure of the polulations changes. The pubescence of young animals and reproductive activity of adults decrease, the social structure in vote micropopulations limited by biotope boundaries changes. The course of reproduction of votes in autumn was dependent on foraging conditions. The reproduction of animals takes place more successfully in the biotopes with the predominance of turfforming grasses.