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

Abstract

We studied colony composition and communal food caching of Brandt's voles ( Lasiopodomys brandtii) in Hexiten Banner, Inner Mongolia, China. Brandt's 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. Brandt's voles stored food collectively in communal food caches in late autumn. Artemisia frigida was the dominant plant in the food caches of Brandt's 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 Brandt's 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 Brandt's voles in Inner Mongolia.