Ansell's mole-rat, Fukomys anselli, is a social subterranean mammal and exhibits an extreme reproductive division of labour. Reproduction in the colony appears to be restricted usually to a single female. Complete colonies captured throughout an entire calendar year were euthanased and the histology of the gonads and plasma hormone concentrations were measured in reproductive and non-reproductive members of both sexes. In males, the circulating levels of testosterone were highest in the reproductive male. The mean testes mass for male corrected for body mass was lower than that of the non-reproductive male. However, the mean testes volume of reproductive males was greater than that for the non-reproductive males and the seminiferous tubule diameter was greater in reproductive males. Reproductive females characteristically possessed corpora lutea of ovulation and pregnancy in their ovaries and this was met with much elevated progesterone concentrations in these females. In contrast, non-reproductive females showed a complete range of follicular genesis, but they did not possess corpora lutea of ovulation or pregnancy, in turn they show depressed progesterone concentrations. The current available evidence suggests that in Ansell's mole-rats, the non-reproductive males and females refrain from sexual activity by being subordinate and moreover related to the breeding pair.

Mammalian parental investment (i.e., care of descendant offspring) is largely biased towards maternal contributions due to the specific feeding needs of mammalian offspring; however, varying degrees of paternal investment have been reported in about 10% of all mammalian species. Within the order Carnivora, paternal contribution to rearing offspring is particularly high: an estimated 32% of all studied carnivore species exhibit direct paternal care. Despite the prominence of paternal investment in carnivores, the endocrine basis of this behaviour is not well understood. This review examines the current -highly constrained --state of knowledge about the endocrine basis of carnivore paternal investment. We attempt to link changes in androgen and glucocorticoid levels with variation in direct and indirect paternal care behaviour making specific predictions regarding the way forward. Well studied species such as bat-eared foxes (Otocyon megalotis), dwarf mongoose (Helogale parvula) and meerkats (Suricata suricatta), where social dynamics are relatively well understood, can act as ideal model systems through which we may further investigate the endocrine basis of paternal investment in carnivores.

Aside from some studies on cooperatively breeding species, we know little about the underlying endocrine mechanisms of social behaviour in the order Carnivora. We investigated the correlations between steroid hormones and social behaviour in a socially monogamous canid, the bat‐eared fox (Otocyon megalotis). We collected faecal and observational data over 15 and 22 months, respectively, from 14 wild bat‐eared foxes in the Kalahari Desert, South Africa. These data were used to describe the relationship between faecal hormone metabolite concentrations and social behaviour. Faecal androgen metabolite (fAM) concentration differed by sex and mating season and was positively associated with faecal glucocorticoid metabolite (fGCM) levels. Male foxes had substantially higher fAM concentrations (median: 9.99 μg g−1 org. content, IQR = 7.39–11.62 μg g−1 org. content) than females (median: 1.93 μg g−1 org. content, IQR = 1.68–2.56 μg g−1 org. content). Higher fAM concentrations were associated with more social tolerance in female but not male foxes. Concentrations of fAM were positively associated with rate of inter‐group encounters in female foxes. Furthermore, fAM concentrations were also positively associated with the overall rate of negative social interactions for females. Finally, fAM concentrations were positively associated with scent‐marking behaviour in male, but not female foxes. There was no association between fGCM concentrations and any of the observed social behaviours in male foxes. Female foxes had a negative relationship between fGCM concentration and marking behaviour as well as social tolerance. There was no difference in fGCM concentration between female (median: 0.19 μg g−1 org. content, IQR = 0.16–0.23 μg g−1 org. content) and male (median: 0.22 μg g−1 org. content, IQR = 0.19–0.31 μg g−1 org. content) foxes. Our study is the first to describe the endocrine correlates of aggressive and affiliative behaviour in the monogamous bat‐eared fox. Androgens play an important role in mating behaviour in monomorphic, monogamous species where females might drive sexual selection.

For spiny mice, detailed long-term data on reproductive endocrine function is lacking, as limited blood volumes make frequent collections of individual plasma samples for hormone monitoring impractical. To provide the necessary tools in order to fill this gap, this study examined the suitability of two enzyme immunoassays for monitoring male and female reproductive function in the southern African spiny mouse (Acomys spinosissimus) based on faecal hormone analysis. Fourteen non-pregnant and one pregnant female and 24 male spiny mice were wild-caught and subsequently monitored under controlled conditions. Thirteen of the 14 non-pregnant females revealed elevated faecal progestagen metabolite concentrations with eight individuals showing indications of a luteal phase. Two females showed two post-ovulatory luteal phases with estimated cycle lengths of 16 and 18 days, respectively. The pregnant female had an elevated (231%) mean faecal progestagen metabolite level compared with the overall mean baseline hormone concentration determined for the 14 non-pregnant females. Males exposed to a long photoperiod, simulating summer-related breeding activity, exhibited a 47.8% increase in faecal androgen metabolite levels compared with males exposed to a short photoperiod. Collectively, the data demonstrated that reproductive endocrine function can be monitored in male and female spiny mice by measuring respective faecal hormone metabolites.