Ecology of The Common Mole-Rat (Cryptomys Hottentotus) In Rhodesia

Abstract

The common mole-rat (Cryptomys hottentotus) was studied for 8 months, principally on the campus of the University College of Rhodesia and Nyasaland at Salisbury in Southern Rhodesia. Eighty-eight mole-rats were captured with snares set below ground in tunnel systems dug by the animals in search of food. Small mounds are formed resembling those of moles and pocket gophers in North America. When the ground is moist and easily dug, much time is spent in storing food within an intricate home burrow system beneath large termite hills. In the dry season as the ground becomes dry and hard at the surface, the molerats no longer push up mounds but redistribute the loose soil in abandoned tunnels. During the rainy season much of their habitat is flooded and they are restricted to the home burrows. Captive mole-rats of the genera Cryptomys and Heliophobius dug with the incisor teeth, and used the feet and tail to push loose earth along the tunnel and onto the surface of the ground. Vibratory movements of the hind limbs tamped the loose earth into a plug that blocked the burrow opening. The mole-rats ate, almost exclusively, the bulbous bases of black seed grass (Alloteropsis semialata). A density of three mole-rats per acre was estimated for the 26.8-acre study plot. The scarcity of pregnant females and the absence of sperm in males taken during the study indicate that the breeding season must occur in the middle of the rainy season. Small Utters, a large number of adults and the closed burrow system all indicate a low mortality rate in the species. The low mobility and high degree of isolation of local populations are associated with a high degree of variability in coat color and head markings.