Adolescent female monkeys in Japan have repeatedly engaged in sexual behaviors with sika deer, for reasons that are not yet clear, according to researchers
Adolescent female monkeys in Japan have repeatedly engaged in sexual behaviors with sika deer, for reasons that are not yet clear, according to researchers who study macaque behavior.
The study, published in the peer-reviewed Archives of Sexual Behavior, follows up on a single report from earlier this year of a male macaque mounting a female sika deer on Yakushima Island.
That report was intriguing, but a co-author of the new study told The Guardian it was essentially anecdotal. “Even the sexual nature of this interaction was not clearly demonstrated,” said Noëlle Gunst, a researcher at the University of Lethbridge in Canada. So she and her colleagues sought to nail down the nature of the mounting.
Looking at a different set of relationships — adolescent female monkeys and deer, particularly male deer, in Minoo, Japan — the researchers found interactions that definitely seemed to be sexual in nature. (The female monkeys were climbing onto the deer and grinding their genitals against the deer’s backs. Yes, there’s video.)
Japanese macaques are known to ride deer like humans ride horses, for fun or transportation — behavior the deer seem to tolerate in exchange for grooming and discarded food. But these monkeys were up to something different.
The researchers compared the monkey-deer interactions, which happened during mating season, with homosexual monkey-monkey interactions, where female macaques mount each other. They paid close attention to the “mounting postures” the monkeys assumed on the deer, and the vocalizations they made, to determine that the interactions were, in fact, sexual… at least for the monkeys.
Some of the deer shook the monkeys off and fled the situation. But adult male deer, in particular, were likely to just stand calmly as the female monkeys thrusted. In some cases, the male deer kept eating.
Five of the female monkeys had “successful heterospecific consortships” with deer. That is, they had “a temporary, but exclusive, sexual association” with an individual from another species, with “three or more mounts within a 10-minute period.
