THE COLONY STRUCTURE AND DOMINANCE HIERARCHY OF THE DAMARALAND MOLE-RAT, CRYPTOMYS-DAMARENSIS (RODENTIA, BATHYERGIDAE), FROM NAMIBIA

Cryptomys damarensis is one of the few subterranean rodents which is social. This species is found in the semi-arid regions of southwestern and central Africa. The Damaraland mole-rat occurs in colonies of up to 25 individuals, in which reproduction is limited to one or two of the largest males and the largest female in the colony. The mean colony size is 18 mole-rats (n = 6 colonies). The mean colony biomass is 2.32 kg and the sex ratio is female biased (0.71-0.78). The number of mole-rats in each colony, the mean body mass and the sex ratio are described for six field-captured colonies, three of which were captured in their entirety. The dominance hierarchy of two colonies of C. damarensis was found to be linear with a value of between 0.94 and 1.00 calculated from Landau's linearity index. Dominance was found to be related to gender, with the males more dominant than females. The reproductive individuals are the dominant animals within each respective gender. The non-reproductive females rank lowest in the hierarchy.