Temporal patterns of den use suggest polygamous mating patterns in an obligate monogamous mammal

Abstract

Mating systems in animal societies contain both social and genetic components. Deviations between these components may have important ramifications for our understanding of the evolution of animal reproductive strategies and their ecological correlates. However, although there is ample evidence for discrepancies between genetically assigned paternities and social associations in birds, relatively few studies have documented such differences in mammals. Moreover, few studies have addressed how deviations between social mating associations and actual mating activities influence patterns of resource utilisation in males and females. The aardwolf is a socially monogamous hyaenid that exhibits polygamous mating behaviour. Suitable den sites for resting and rearing offspring is an important resource for terrestrial mammals, and dens are vital to aardwolves as thermal refugia for protection of offspring. We show that temporal patterns in aardwolf den use relates to predictions from polygamous mating rather than social monogamy. Male aardwolves used more dens, changed dens more frequently and stayed in dens for shorter periods of time than females during both wet and dry seasons. We suggest that lower male den fidelity is either caused by males trying to maximize female encounters and to monitor female activity, or that it had evolved as a non-adaptive behaviour related to elevated androgen levels. Our data did not point to territorial defence or space use optimization as cause for the observed sex differences, since we did not find any sex or seasonal differences in the spatial patterns of utilized dens. We suggest that aardwolves may have been ecologically constrained to exhibit social monogamy but that polymagous mating is maintained through extra pair copulations. We recommend that the evolutionary stability of these two conflicting strategies of male fitness maximization must be further investigated.