There’s a famous picture that has probably been burned into the retinas of anyone who spends a lot of time on the internet. It’s a squirrel, standing up, with a surprisingly huge pair of testicles dangling beneath him. That’s a Cape ground squirrel and the image isn’t a fake. Males have a scrotum that’s 20% of their body length (excluding the tail) and their penis is more than twice as long.
These mighty genitals suggest that sex, and sperm in particular, is a serious business for Cape ground squirrels. To get the best odds of fathering the next generation, they need to ensure that it’s their sperm that fertilises the female’s eggs and not those of rivals. So they make a lot of it; hence, the oversized testicles.
With sperm being so important, it’s odd that some Cape ground squirrels regularly waste theirs. Yet that’s exactly what Jane Waterman saw while studying wild squirrels in Namibia. Some of them would masturbate, apparently squandering their precious sperm. What does squirrel masturbation look like? Apparently, it’s rather acrobatic. I’ll let Waterman describe it herself:
“An oral masturbation was recorded when a male sat with head lowered and an erect penis in his mouth, being stimulated with both mouth (fellatio) and forepaws (masturbation), while the lower torso moved forward and backwards in thrusting motions, finally culminating in an apparent ejaculation, after which the male appeared to consume the ejaculate.”