Monkeys engage in bestiality with deer

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.

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.)

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.

https://www.npr.org/sections/thetwo-way/2017/12/15/571175252/scientists-say-japanese-monkeys-are-having-sexual-interactions-with-deer