Male hyena endurance data

In traditional definitions of endurance rivalry, individuals compete to remain reproductively active longer than their rivals, but these time periods are typically brief, such as a single breeding season. Here, we explored endurance rivalry among adult males in a long-lived species that breeds year-round, the spotted hyena (Crocuta crocuta). We found that most dispersing males navigated the adaptive challenges of remaining in their new clans (“enduring”) for over two years before siring their first cub. Additionally, sires remained in their new clans at least four years, whereas males that never sired any cubs typically disappeared by their fourth year of tenure. This suggests that males might incorporate their initial reproductive success in the clan into their decisions regarding whether to “endure” by remaining in the current clan or to disperse again to another clan. Finally, we used Bayesian mixed modeling to explore variation in annual male reproductive success, which we found to have a positive linear relationship with tenure and a quadratic relationship with age. A male’s rate of social associations with adult females, but not aggressive interactions with those females, was predictive of his annual reproductive success. We also found substantial individual variation in annual reproductive success across males. Our results support the notion that male spotted hyenas compete via an extended endurance rivalry; tenure unequivocally improves male reproductive success, but advanced age does not, and questions remain regarding other traits that might be salient to the rivalry or to female mate choice in this species.