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Urinary testosterone concentrations in males and urinary progesterone and oestradiol concentrations in females were measured in the Cape mole-rat (Georychus capensis) and compared for the summer and winter periods. The Cape mole-rat breeds seasonally, with sexual activity and subsequent pregnancy recorded during the winter months in the southern hemisphere. Despite the fact that it has a distinct breeding season, seasonal differences in urinary hormone concentrations of both male and female Cape mole-rats were not statistically significant. This finding supports the notion the Cape mole-rat may have the opportunity to operate as an opportunistic breeder if fortuitous environmental conditions arise, such as unseasonal rainfall, occurring at these normally non-favourable times of the year.

The reproductive cycle of mammals can be inhibited by 2 factors, seasonal breeding and dominance control, both potentially important in mole-rats. The gonads and gonadal steroids of dominant (reproductive) and subordinate (nonreproductive) Natal mole-rats (Cryptomys hottentotus natalensis) were investigated to determine the effects of season and social status on reproduction within natal colonies. We found no seasonal differences in concentrations of gonadal steroids of male or female mole-rats. Similarly, the gonadal histology and volume showed no seasonal differences. These results, together with the presence of fetuses, confirm the potential for breeding throughout the year. Reproductive and nonreproductive mole-rats display comparable testosterone and estrogen concentrations in males and females, respectively. Follicular development and the presence and number of sperm in nonreproductive animals suggest that the reproductive quiescence in nonreproductive animals is likely to result from behavioral interference of dominant animals or incest avoidance (or both). Urinary progesterone concentrations of reproductive females were significantly higher than those of nonreproductive females. Although follicular development in nonreproductive females proceeds to the level of Graafian follicles, the number of these follicles present in nonreproductive females was significantly less than that in reproductive females. The reproductive physiology of the Natal mole-rat compares with other loosely social mole-rat species inhabiting mesic areas.