In Africa, lions may be the “king of the jungle”, but across the vast prairies of the North American frontier, the American bison was once known as the “monarch of the plains.” The largest land animal on the continent, weighing in at up to 2,400 pounds, these shaggy behemoths, often conflated with buffalo (a different animal), once ruled the breezy grasslands in colossal herds. Though these animals are strongly associated with the American West and various Native American cultures, it also bears mentioning that you can’t spell “bison” without “bi” — and for good reason.
Observers have known about the bisexual proclivities of bison for as long as humans have been around them, but one of the earliest documented references in the scientific literature come from a 1958 paper by zoologist Tom McHugh. In the decades since, researchers have recorded bison sexual behavior in quite a bit of detail.
In the wild, male bison are, in the words of biologist Bruce Bagemihl, “functionally bisexual.” Gathering half a century of research, he documented that male bison engage full anal intercourse, often with the receiver actively positioning himself and backing up to help the bull on top. These same-sex mountings generally last twice as long as the male-female varieties. Sometimes they begin as play-fighting that turns sexual. In other cases, one male rests his chin on another male’s rump and pants. During the rutting season, same-sex mounting could happen multiple times daily. It’s not like there’s much else to do in the prairie.
Male bison also form what are known as “tending bonds” — temporary courtships where two bison mates stay nearby one another, share food, and defend each other for a period of hours or days. As Bagemihl noted, “younger males sometimes form ‘tending groups’ of four to five individuals who take turns mounting one another or the same individual. What about females? Same-sex behavior among wild female bison is very rare, however in captivity, females will mount one another as well.
Similar to many other animal species who exhibit bisexual behavior, male and female bison tend to live most of their lives apart from one another. However, same-sex behavior isn’t merely due to lack of opportunity. Even in herds curated by humans to ensure that all males have access to female mates, same-sex behavior remains common. And not just common, but more common than opposite-sex mounting, as over 55% of mounting among younger males is same-sex.
Scientists believe that bisexual behavior among bison serves two general purposes. First, to help form bonds and function as a kind of training and “practice” for opposite-sex mounting, and also for the role it plays in establishing dominance hierarchies among male groups. Given that males still choose to mount each other even when females are around, clearly they must also enjoy it.
These majestic beasts, like their European cousins, were once driven to the brink of extinction. Thankfully, their population has been stabilized, though nowhere near the levels of centuries ago. It would be a tragedy to deprive the world of these monarchs. Hopefully we’ll one day see the return of the bi kings of the plains!