The Cape ground squirrel takes sex very seriously. For the males, the scrotum is about 20% of their body length, and the penis is twice as long; if you don’t believe me, this particular image will probably change your mind – but be warned ! It will be burned onto your brain for quite a while.

Thing is, if you’re a male squirrel, you obviously want to make as many little squirrels as you can, so if you want to maximize your chances, you have to make sure it’s your sperm that fertilizes the female eggs (because we all know just how easy female squirrels are). So you make a whole lot of sperm – hence the big… testicles. But if their sperm is so valuable, why would they waste it by choking the chicken masturbating ? And even more interesting, how does a squirrel masturbate ? I’ll let Jane Waterman, an expert (in squirrels, not the other thing), tell you about it:

“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.”

In case you didn’t know, lots of mammals masturbate, including primates and rodents. In every case the question remains – why waste the sperm ? The obvious answer is the classic one: males are horny, females aren’t. But there are alternate theories that spark particular interest; one of them suggests that maybe they flush out old sperm to make way for better and faster… cadets. But Waterman has another idea, at least when it comes to Cape ground squirrels; and she should know, after spending two thousand hours spying on them with a pair of binoculars and noting every sexual interaction between them.

Her notes suggest that squirrels masturbate more often when the females are in the mating period, and that dominant ones do it more often than subordinates (now that’s something). What’s even more surprising, those who have had sex do it more often than the unlucky ones; and they do it after sex, which rules out the ‘sperm cleansing’ theory, in which they would do it before. So she concluded that masturbating can’t actually be some sort of signal, it had to be something else.

The conclusion she came to ? It’s an act of self medication. They do it to clean their genitals and thus lower the risk of a sexually transmitted infection. It explains (read this in a crazy scientist voice) EVERYTHING ! They could do it by urinating, but since they live in desert areas, it’s pretty hard to lose water just like that, so masturbating is the next best thing. Now that’s something to ponder while reading squirrel stories to your kid.

Pictures 1 2

Enjoyed this article? Join 40,000+ subscribers to the ZME Science newsletter. Subscribe now!