Kleptogyny

(n.) a mating strategy in which a low-ranking male mates with a female while the alpha male is distracted

Words like kleptomania and kleptocrat come from a Greek word, kleptes, for a thief.

Among the less familiar entries in this part of the dictionary are the likes of kleptoparasite (a creature that steals food from another), kleptolagnia (a sexual attraction to thievery), and kleptogyny—a mating tactic in which a low-ranking male mates with a female while the alpha male of the same group is somehow distracted. And, as we pointed out on Twitter, in evolutionary biology this tactic is better known as the ‘sneaky fucker strategy’.

Literally meaning ‘woman thieving’, kleptogyny is a mating tactic typically observed among herd mammals—and in particular groups wherein one male rules over a party or ‘harem’ of females. Deer tend to be the usual suspects here, but kleptogyny has also been observed in elephant seals, with lower-ranking male seals sneaking into a harem to mate with unattended females, while the dominant male is distracted fighting off a fellow challenger.

Etymologically, in English klepto– words like these tend to be relatively modern: kleptomania is the oldest of the bunch, coined during the early days of psychiatric science in the first half of the nineteenth century. Many of the others are much more contemporary, with kleptolagnia first described in 1913, and kleptoparasitism only known as such since the early 1950s. Kleptogyny is an even more recent invention: it was first brought to wider attention in a 1977 article in New Scientist magazine, that noted this behaviour among rutting red deer stags vying for control of an alpha male’s harem:

The benefits of a larger harem in terms of increased reproductive potential, are clear, but what of the costs? ... For a bachelor without a harem the benefits outweigh the costs, and one finds that harem owners initiate fights less often than bachelors. The costs are also increased when both stags hold harems, largely because young stags take advantage of the fight to steal hinds from the harems. (This is known as kleptogyny, but [University of Cambridge zoologist Professor Tim] Clutton-Brock and most others prefer ‘the sneaky fucker strategy’.)

Note too that this article also introduced kleptogyny’s slightly less subtle alternative name, suggesting both terms were established by the time it went to print.