It’s a dog’s life – aggressive male hyenas fail to impress the girls

The old adage “treat them mean keep them keen” has been turned on its head by new research published in the Royal Society’s journal Proceedings: Biological Sciences today; at least as far as hyenas are concerned.

Scientists studying Serengeti spotted hyena clans in Tanzania found that male hyenas displaying “friendly” behaviour had much more luck with the ladies than their more aggressive counterparts.

Using genetic techniques, the researchers discovered that males rarely sired offspring with females that they attempted to manipulate through monopolization or harassment, whereas males that invested time and energy in developing amicable relationships with females successfully sired offspring.

Dr Marion East, one of the authors of the study said: “What this paper reveals is the enormous amount of sexual politics among members of large hyena clans. I suspect many might think that females would choose to mate with socially dominant males. Indeed this was an assumption made by many early behavioural scientists, but our results show this is not the case with hyenas. The friendlier male hyenas are and the longer they stick around, the more favourably they are looked on by female hyenas.”

Friendly tactics included grooming, greeting and amicable gestures. Aggressive tactics were split into high and low levels of harassment. Low
levels of harassment involved a male approaching a female aggressively, lunging at or biting the female or attempting to mount when the female did not cooperate. Intense harassment termed “baiting”, involved coalition of male attacking typically solitary females. None of the males that harassed females sired cubs with them.

The study revealed that female hyenas favoured males who had spent a longer time with the clan. The number of cubs sired by these males increased with tenure, with most progeny sired when they held tenures of at least four years. Males sired 10 litters on average when tenured less than 2 years and 56 when they had tenured for four or more years. The number of females with whom these males sired cubs with also increased with tenure. Males mated with eight females when tenured less than 2 years and 46 when tenured for four or more years.

Other tactics used by males in attempts to woo females included shadowing and defending. Shadowing occurred when males followed a female for weeks or, in some cases months, and defending occurred when a male prevented other males interacting with a female. Neither of these tactics conferred any advantage to hyenas using them. Males gained paternity with females that they shadowed as often as with females they did not shadow and no males sired litters with females they had defended.

In a further blow to the male psyche, research revealed that female hyena’s have developed tactics to confuse belligerent males and keep them in their place. The research indicated that males may find it difficult to determine when females are receptive and fertile, making it difficult for them to know when to coerce them. The researchers also suggested that some females mate with multiple males to confuse paternity and counter infanticide by non-sires. So although females socially dominate males, they need to employ tactics to undermine the potential advantage of males of coercion.