THE SOCIAL-STRUCTURE AND DOMINANCE HIERARCHY OF THE MASHONA MOLE-RAT,CRYPTOMYS DARLINGI (RODENTIA, BATHYERGIDAE) FROM ZIMBABWE

Cryptomys darlingi is a social subterranean rodent mole which inhabits the mesic regions of south-eastern and central Africa. Mashona mole-r ats live in small colonies (5-9 animals) in which reproduction is norm ally restricted to the largest male and female in the colony. The nonr eproductive members in a mature colony cannot be placed into clearly d efined work-related groups based on body mass. The dominance hierarchy of a young colony was found to be linear, with a value of 1.00 calcul ated from Landau's linearity index, while that of a mature colony of n ine mole-rats was almost linear (0.77). Dominance was found to be rela ted to gender in the mature colony, with males more dominant than fema les, and to age in the young colony. The reproductive mole-rats are th e dominant animals within their respective genders. Dominance appears to correlate positively with body mass (rs = 0.77 in the mature colony and rs = 0.93 in the young colony). Popularity studies show that smal ler animals and females tend to be more popular than the larger massed individuals or males. In the mature colony which contained predominan tly adult animals, the reproductive pair was among the least popular. While in the young colony, composed predominantly of sub-adult and juv enile animals, the reproductive pair was the most popular. Social orga nization within Mashona mole-rat colonies is compared with other south ern African Cryptomys species.