For animals, reproduction is a biological imperative, an instinct to pass their genetics onto the next generation. This translates into a complex dance of competition, dominance, and courtship for the males of the species. The process is even more fascinating in spotted hyena clans, with their hierarchies and intricate systems of power-plays and alliances. Long-term behavioural research and hormone analysis by the Hyena Project in Tanzania reveal further insight into the complicated romantic lives of spotted hyenas.
As is the case with the females, every individual male hyena in a clan has a particular rank, with immigrant males finding themselves at the bottom of the clan hierarchy. Status and dominance equate to better access to both food and females. The researchers’ questions set out to answer related to how this social rank influences an individual’s reproductive success. Were high ranked males more successful because they are stronger and fitter and, therefore, a more attractive mate choice likely to produce sturdy offspring? Or, given the intricacies of hyena society, was the reason more complex? The results of the research indicate the latter.
Due to the clan hierarchy and their unique genital structure, female spotted hyenas control the process of mate selection entirely. Extended courtships are the order of the day for hopeful males, and they will nurture their relationships with certain females, sometimes for years at a time. The supplicant male will do everything in his power to convey his intentions to a receptive female, bowing and scraping in a comic display of humility. If he is successful, she may just allow him to mate with her. According to the study results, high-ranked females are more in demand than those of a lower rank, which is to be expected given the benefits conferred on offspring of higher-ranked females (“the silver spoon effect”).
Naturally, this intensive courtship requires both time and energy, things that the study indicates are in shorter supply for lower-ranked males. In collecting over 400 samples of fresh hyena scat, the researchers analysed levels of faecal glucocorticoid metabolite concentrations – cortisol, a stress hormone – to estimate the psychological effects of social interactions between clan individuals. The results indicate that male-male interactions are more stressful for the low-ranking males than for high-ranking ones. These interactions are an inevitable part of everyday life for spotted hyenas. The males are obliged to maintain relationships with clan-mates but low-ranked males, understandably, spend more time on their own, avoiding stressful situations. In essence, low ranked individuals invest less time in sexual activities, social activities and spend more time away from clan mates.
Researchers at the Hyena Project in the Ngorongoro Crater in northern Tanzania have recorded behavioural data of spotted hyenas for over 20 years. In recognising each clan member and understanding their histories and dynamics, the authors of the study were able to use the biological information imparted by hormone analysis to interpret observed behavioural trends.
In conclusion, the researchers note that fortunately, for the low-ranking hyena males, chances are their time will come. ‘Social queuing’ means that a male hyena’s status and rank will increase when a higher-ranking individual dies or disperses. Rather than using physical strength and violence to increase their chances of reproducing, it is simply a matter of patience for most.
The full study can be accessed here: “The interplay between social rank, physiological constraints and investment in courtship in male spotted hyenas“, Davidian, E., et al, (2020), Functional Ecology
A Plain Language Summary written by the authors can be accessed here: Why do top dogs usually get the prettiest ladies?
Read more about Hyenas here
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