The structure of a population of mole-rats, Tachyoryctes splendens, (Rodentia: Rhizomyidae)


  • Jennifer U. M. Jarvis

    1. Department of Zoology, University of Nairobi, Kenya
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      Department of Zoology, University of Cape Town, Rondebosch, Cape, South Africa.


803 mole-rats, Tachyoryctes splendens, trapped at Nairobi, Kenya, were used in a population study. Because of their discrete burrow systems and solitary fossorial nature, mark-release methods for population assessment were impracticable and a method was devised using kill-trapped animals.

A significantly higher number of adult female than adult male Tachyoryctes were trapped, this however, was found to be due to preferential trapping of females.

Tachyoryctes has an average (pre-resorption) litter size of 1.9. The uterine placental scars produced by each litter persist for considerable periods, probably throughout life. It was possible to use the number of placental scars to divide the female population into groups based on the number of litters they had had.

Young female mole-rats mature in about 120 days. The average time between successive litters was calculated to be 173 days and it was possible to estimate the age of each female mole-rat from the number of litters she had had. Using this data a life table was constructed.

Except for a period of lowered mortality on first attaining sexual maturity, the death rate of the female population was fairly constant, suggesting that fossorial life offers equal protection to all age groups.

Tachyoryctes has a low annual rate of recruitment (1.37) which again is probably directly attributable to the protection offered by their fossorial mode of life.