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Resource partitioning may allow species coexistence. Sand dunes in the typical steppe of Inner Mongolia, China, consist of desert, shrub and grass habitats, providing an appropriate system for studies of spatial niche partitioning among small mammals. We collected data to verify the niche separation hypothesis that coexisting small mammals would separate into spatial niches, and the productivity hypothesis that the highest species richness and overlap were to be expected in the most productive and diverse shrub habitat of the north-facing slopes, in contrast with the less productive grass and desert habitats of sand dunes. We trapped small mammals on 44 sand dunes in the summer of 1984 using snap traps. We captured 12 species of small mammals among three types of habitats.Cricetulus barabensiswas a habitat generalist, present in all three types of habitats.Spermophilus dauricuswas present only in the grass habitat,Allactaga sibiricaandDipus sagittaonly in the desert habitat, andApodemus peninsulaeprimarily in the shrub habitat. The shrub habitat hosted the largest number of small mammal species among the three types of habitats, supporting the productivity hypothesis. Habitat separation is an important mechanism for structuring small mammal communities in Inner Mongolia grasslands. [ABSTRACT FROM AUTHOR]

Abstract: Spacing behavior is important to the population regulation and social organization of rodents. However, little is known regarding the factors influencing space use by rodent social groups. We tested the hypotheses that food resources in the typical steppe would be so abundant that food availability would not be a limiting factor of home-range sizes of social groups of Mongolian gerbils (Meriones unguiculatus). We also assessed the effects of social organization on the home-range size of social groups of gerbils, using capture–recapture methods. Home ranges of social groups of Mongolian gerbils did not differ in size between the breeding and non-breeding periods; however, home ranges overlapped more during the breeding period than during the non-breeding period. Overlap of home ranges might allow male gerbils to access female mates of neighboring colonies during the breeding period. Home-range sizes of social groups were positively related to number of males during the breeding period, but positively related to group size and number of females during the non-breeding period. Therefore, social organization influenced home-range sizes of social groups. Our hypothesis that food availability is not a limiting factor of space use by social groups of Mongolian gerbils from spring through autumn was supported. [ABSTRACT FROM AUTHOR]