Sitting mounting posture with pelvic thrusting. Screengrab via YouTube.

The monkeys are having sex with deer. The humans are being creeps and watching the monkeys having sex with deer.

Video taken from “A Quantitative Study of Heterospecific Sexual Behaviors Performed by Japanese Macaques Toward Sika Deer,” Archives of Sexual Behavior.

A study of female macaques published earlier this week in the Archives of Sexual Behavior confirmed suspicions from another incident reported earlier this year that, yes, monkeys are having sex with deer (or, exhibiting sexual behavior on deer). Researchers studied two groups averaging 80 monkeys each, both living in the Minoo Quasi-National Park of Japan; they found the deer-humping to be taking place only amongst one group, and only by females.

The study, for human reference, is like a monkey-on-monkey Joy of Sex compendium (language theirs):

  • “bird-dogging”: frozen stance and intense gazing, hindquarter presentations, inclined-back presentations
  • “tantrum”: crouching on the ground or against a branch while screaming
  • “body movements and gestures”: lip quivering, head bobbing, ground smacking, hindquarter sniffing, hands-on-hindquarters solicitations, pushing, grabbing, and body spasms
  • “sexual vocalizations”: [Author note: understood amongst researchers]
  • “double foot-clasp mounts”: the mounter grasping with her feet between the mountee’s ankles and hips and with her hands on the mountee’s back
  • “reclining mount”: when the mounter laid ventrally on the mountee’s back
  • “sitting mounts”: when the mounter sat on the mountee’s back in a jockey-like position, while grasping the mountee’s upper back with her hands and the mountee’s lower back with her feet
  • “standing mounts”: the mounter grasped from behind the mountee’s back with her hands, while either standing bipedally with her feet on the ground and her knees slightly bent or standing with one foot on the ground and the other grasping the mountee’s hind limb

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Over two months, researchers recorded 13 “successful” sexual encounters (“successful”: three or more mounts within a ten-minute period).

Humans, the only other species who freely record everybody else doing it in such great detail, ask prying questions like: why???

According to Dr Cédric Sueur of the University of Strasbourg, a co-author of the original study, tells the Guardian that it might just be attributed to females not having enough males to go around during mating season. “Monkeys do this according to the sex ratio at the reproductive season: if females cannot have access to males, they can have homosexual relations or relations with a deer,” he says.

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The deer do not seem to mind, but THANKS FOR ASKING.