The Spatiotemporal Structure of Rodent Populations in the Steppe Zone of Western Siberia

The spatial structure of populations has been studied in two rodent species inhabiting the subzone of meadow steppes of the steppe zone of Omsk oblast: the narrow-sculled vole (Microtus gregalis Pall.) and steppe lemming (Lagurus lagurus Pall.). Their populations are represented by combinations of territorial family groups whose structure and spatial distribution vary by season depending on population density, the phase of the population cycle, and the status of their members in the population. In the areas cohabited by M. gregalis and L. lagurus, the pattern of territory use and the rhythm of animal activity during the day depend primarily on their total density: under conditions of low density, the population groups of both species are spatially separated; at increased density, they are distributed with respect to the pattern of daily activity. Both species jointly use part of the territory but at different times of day: M. gregalis, mainly at night and in the morning; L. lagurus, in the daytime.     

The Structure of Narrow-Skulled Vole (Microtus gregalis Pall.) Colonies in Western Siberia

The structure of Microtus gregalis colonies was studied in different parts of the species range in Western Siberia, both in the south (Omsk oblast) and in the north (Yamalo-Nenets Autonomous Area), in 1999 and 2000. The colonies studied in the steppe zone of Omsk oblast, southern tundras of the Yamal Peninsula, and mountain tundras on the northern slopes of the Polar Urals prove to have some common structural features. In Omsk oblast, seasonal variation in the area of colonies and the number of entrances to the burrows was revealed, although the general structure of colonies (the pattern of tunnels and location of the nest and storage chambers) was largely the same in spring and autumn.