Adolescent snow monkeys on Yakushima Island were observed to be engaging in sexual activities with sika deer last year and now a study published in the Archives of Sexual Behaviour has confirmed this unusual occurrence.
"We observed multiple occurrences of free-ranging adolescent female Japanese macaques performing mounts and sexual solicitations toward sika deer," the scientists reported in the study.
The female monkeys were seen climbing onto the backs of deer, thrusting their pelvises and rubbing their genitals on them. According to the report there were body spasms, screaming and high pitch calls accompanying the sexual act.
Such encounters, which are sexual in nature between distantly related species, are very rare, with the only other documented example being the sexual harassment of king penguins by Antarctic fur seals.
Most of the sika deer that the monkeys were having sex with were adult males, although the scientists also observed encounters with two female deer and three young males.
According to the publication, further studies need to be conducted to find out whether the phenomenon is short-lived or is something more long-term.