Having a harem sounds like a pretty sweet deal. After all, variety is the spice of life, no? But this breeding and social arrangement has its risks. For humans, you have the drama of sister wives. And for wild pheasants (Common, in Europe; or Ring-necked, stateside), a bigger group may actually present an existential danger.
Newly published research in the journal Animal Behaviour suggests an ideal harem size for pheasants of 2.7 female birds for every male. Scientists from the University of Exeter in England and the Game & Wildlife Conservation Trust (GWCT) found that having more females in the group makes each individual female a little less stressed about watching out for threats, and more able to forage in prep for breeding. But for the male, having more mates to watch out for decreased his ability to successfully detect and fend off rivals and predators.
So, to paraphrase an old saying, for pheasants eternal vigilance is the price of polygamy. And the intensity of that vigilance appears to correlate with the number of gals in the harem. Maybe monogamy, with just one partner to support and protect, isn’t so bad after all.
Image of male pheasant and his harem courtesy of GWCT.