Communal food caches and social groups of Brandtʹs voles in the typical steppes of Inner Mongolia, China

We studied colony composition and communal food caching of Brandtʹs voles (Lasiopodomys brandtii) in Hexiten Banner, Inner Mongolia, China. Brandtʹs voles lived in colonies throughout the year. The average number of voles in a colony was 16.7 voles in 1986 (n=18) and 21.6 voles in 1987 (n=14). Average sex ratios of vole colonies were about 1:1 in October. Voles born in spring and summer (3–6 months old) accounted for 74% of a vole colony in 1986 and 69% in 1987. Voles born in autumn (1.5–3 months old) constituted 23.2% of a vole colony in 1986 and 25.7% in 1987. Brandtʹs voles stored food collectively in communal food caches in late autumn. Artemisia frigida was the dominant plant in the food caches of Brandtʹs voles, comprising 44.7% of the stored food in 1986 and 71.4% in 1987. The average dry weight of food stored by a vole colony was 4.4 kg in 1986 and 6.4 kg in 1987. Higher population densities might stimulate Brandtʹs voles to store more food; however, given a certain plant standing biomass, increased colony size did not appear to improve the food acquisition efficiency of a vole colony. More studies are needed to reveal the effects of limited food caches on winter survival and spring reproduction of Brandtʹs voles in Inner Mongolia.