The colony structure and social organization of the giant Zambian mole‐rat, <i>Cryptomys mechowi</i>

Abstract

Abstract Cryptomys mechowi is a social subterranean mole‐rat which inhabits the mesic regions of south‐eastern and central Africa. Giant mole‐rats live in colonies of up to 11 animals in which reproduction is normally restricted to the largest male and female in the colony. In this preliminary study on a laboratory‐reared colony, the non‐reproductive members of the colony could not be placed into clearly defined, work‐related groups based on body mass. The colony showed a work frequency related division of labour. Reproductive animals performed little work, 3‐4% of the total work. The non‐reproductive caste was divided into two groups based on the amount of burrow maintenance activity: those performing between 7‐11% of total work and those ranging from 15‐22% of total work. Male members of the colony tended to perform more work than the females. The dominance hierarchy of the colony was found to be nearly linear, with a value of 0.83 calculated from Landau's linearity index. The reproductive animals were the most dominant in their respective gender. Dominance was not age‐related. However, non‐reproductive males tended to be more dominant than non‐reproductive females. Social organization within the giant Zambian mole‐rat is compared with other southern African Cryptomys species in the light of the eusociality continuum.