How do porcupines mate? Very carefully

Story by Jason Bittel
Slate
December 2, 2012
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PITTSBURGH — In forests across Canada and the United States, a peculiar mating ritual takes place each fall. If your windows aren't painted shut, you might open them at night and listen for the tender sounds of porcupine coitus — stark, night-piercing shrieks that could be likened to the noises produced by a banshee banging a Velociraptor.

I know what you're thinking — quills. It's true, the North American porcupine (Erethizon dorsatum) is equipped with something like 30,000 needle-sharp back daggers, and many of them stand between the female's hoo-ha and the next generation of prickly progeny. But the screaming actually comes long before the love-making.

You see, the biggest holdup to porcupine reproduction is location. Except for mamas raising babies — which are known adorably as porcupettes — porcupines are mostly solitary creatures. And when the female is ready to mate, she has just an 8- to 12-hour window of fertility to work with.

This means the fellas need to come from distant territories to find, win, woo and mount her if they are to pass on their genes. Females assist in this process before they come into estrus by lacing the air with a pungent perfume — a come-hither scent created by a combination of vaginal mucous and urine that not even Brad Pitt could make appealing.

Either way, the musk-shake brings all the boys to the yard, and once they are there, it's a brawl for dominance. Uldis Roze knows these battles by their aftermath: "a storm of loose quills." Roze has 35 years of experience working with these creatures and is widely regarded as the Porcupine King. He also has a delightful new book available, "Porcupines: The Animal Answer Guide." After listening to porcupines battle one fall night, Roze returned the next day and collected 1,474 quills belonging to three separate males. Some of the quills bore signs of bite marks, showing that porcupines are practiced in removing rivals' quills from their own skin after such skirmishes.

Once a male has won access to his ladyfriend, the right to mate is his to lose. At this point, many male animals would simply mount the female whether she was interested or not. In humans, we call this rape. Using the same term with animals is problematic, but walk with me.

If rape is nonconsensual sex, then ducks rape. Seals rape. Male bedbugs stab the females with their penis and then leave it there. Water striders coerce sex by threatening to call in predators if the females don't submit. Even dolphins, animals of respected intelligence and the default subject of chick tattoos, gang rape.

None of this is to minimize the crime of rape in humans. I bring it up only to note that the animal kingdom can be a dark place. When dominant male elephants are poached or culled out of the social hierarchy, adolescent males develop strange, violent behaviors, like wantonly murdering rhinoceroses. But not without raping them first.

But porcupines? My friends, porcupines are rape-proof. And not rape-proof like the magical vaginas of Todd Akin's fever dreams. I mean rape-proof like the anti-rape condom.

A porcupine's main defense against predators consists of keeping its backside to a predator. Get too close and you'll snag 500 quills engineered to embed themselves deeper and deeper into flesh. A mouth full of these painful pins has caused many an animal to starve to death. In fact, the porcupine is so well-respected, it wanders the forest day or night without much hurry or fear. Few animals are clever enough to successfully hunt porcupines, though mountain lions, fishers and Chevy Impalas have the most success. That mess of quills is equally effective against its own kind.

Thus instead of force, the male porcupine must use persuasion. He first climbs the female's tree and stands watch from a lower branch until the time is right.

(Yes, porcupines climb trees! Unfortunately, being the second-largest rodent in North America, porcupines also fall out of trees quite a bit. At least their quills are coated with antibacterial fatty acids that seem to protect against infection after self-impalement.)

The waiting game is now on. Because olfactory signaling is an imperfect science — who knows how long it'll take for the guys to show up after a female releases her musk — guarding can begin several days before estrus. Though the male can't force the female to have sex with him, he does have one move that might help get her in the mood.

There's not a lot I can do to make this sound romantic, so I'll just say it. The male porcupine rears up on his hind legs, walks toward the female with a fully erect penis, and proceeds to soak her in urine with a spray forceful enough to shoot 6 feet.

Even more amazing, Roze has witnessed in the tree canopy a male firing off salvos from one branch at a female on another. "It's not like a boy peeing," says Roze. "It's more like an ejaculation, and it's definitely the strangest part of porcupine courting."

We don't know for sure what the urinating is all about, but when other hystricomorph rodents like mice and rats piddle on their mates, we know male pheromones induce estrus in the females. Scientists call it the Whitten Effect.

If the strategy works and the female is ready, she'll lift her tail and allow the male to mount. If she's not ready, she might try to bite him, tail-swipe him, scream in his general direction, or simply shake the urine off and run away.

Eventually, it all works out and the two enjoy about one to five minutes of delicate procreation. The male rests his hands on her tail's quill-less underside or simply allows them to go limp at his sides. Everyone agrees this looks kind of dopey but, during porcupine coitus, there just aren't many safe places for a guy to touch.

The lovers may go through this process several times throughout the course of an hour until one of them climbs up on a branch and declares "Enough!" — though to our unrefined human ears, this just sounds like yet more screaming.

Once the male and female have called it quits, a magical seal forms in the vulva through some sort of enzymatic action in the semen. This mass of starchy, bluish-white material is called a vaginal plug or mating plug. It may assist in reproduction by trapping semen within or dissipating to release more spermatozoa. Additionally, it helps prevent other males from having a chance at fertilization.

All of this contributes to a remarkable 90 percent success rate in female porcupine reproduction. Remembering the once-a-year, 12-hour-window of fertility, it's all the more amazing that the typical female will be pregnant or lactating for 11 months a year — every year — for much of her life. (Porcupines can live 20 to 30 years, though the females do eventually experience menopause and bow out of the reproduction role.)

Jason Bittel

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