Signs of porcupine

Porcupine den

A couple of weeks ago, Dan returned from a walk with Raven and said that they’d discovered a den. It was on the neighbour’s property about a third of the way back along our fence, visible from the fenceline. It was too dark by that point for photos, and the following day was raining, but I did manage to get out with Raven the day after that. He hadn’t been sure what it was, and given Raven’s curiosity in such things, hadn’t spent much time investigating. When I returned with Raven I made sure to have her sit and wait at a safe distance, just in case.

The den was larger than I was expecting, located halfway up a sandy bank, under the overhanging branches of a large fir. The slope had been worn down with the repeated passing of little feet, though there weren’t any obvious tracks in the soft substrate when I got closer. I’d have to look for some other clue to the identity of the owner.

Porcupine den

Fortunately, that clue wasn’t hard to find. Outside the front door, and just inside the entrance, were many dried droppings of a shape and size that I recognized immediately: the round pellet-like winter scat of a porcupine. Nearly all of them were quite old, suggesting that the den site had probably been used last winter. Whether it was being used this winter or not I wasn’t sure. As soon as the snows settle in porcupines start relieving themselves just outside the den (can you blame them? if you were all alone in your cabin in the woods, wouldn’t you just pee off the back porch instead of hiking through the snow to the outhouse, too?), but during the snow-free months, while the animal has more freedom to wander around, it’s more fastidious in its housekeeping. Normally you’re likely to encounter the pale macaroni-shaped summer scat underneath the feeding trees or in the middle of the forest floor, instead.

On occasion, when I’ve found a porcupine den before, I’ve noticed a few shed quills outside the entrance, but I didn’t see any this time. I’m not actually sure if the den is in use yet; I gather that porcupines have separate summer and winter den sites, with the latter often being at ground level and the former being in a hollow in a tree. If he hasn’t yet moved in, that would explain both the lack of fresh droppings and the absence of shed quills.

Porcupine feeding sign - snipped-off balsam fir twigs

I snapped a few photos then carried on along the fenceline, looking for a good place to hop it to cross back to our property. Along the way I passed through a grove of Balsam Fir, which we seem to have more of in the immediate vicinity of our house than any other naturally-occurring conifer (the owners had at some point planted a fair bit of spruce and pine between the house and the road as a privacy screen, but there isn’t much of it in the neighbouring woods). Eyes to the ground as I picked my way across some fallen branches, I noticed small bits of balsam twigs scattered over the forest floor beneath the trees.

Although I scanned the trees themselves and saw nothing, these are pretty clear evidence of porcupine foraging – in all likelihood, the same individual who will be using that den, come winter. I found this interesting, because it was my understanding that northern porcupines feed nearly exclusively on hemlock during the winter months, with a bit of White Pine thrown in for occasional variety. On the other hand, I noticed feeding sign on one of the tamaracks in the bog last winter, and with not too many hemlock in the immediate area, perhaps the animal was just eating what was available.

I’ll have to come back once we have some snow on the ground and see whether the den is occupied and, if so, where he’s feeding. After finding the trails of a porcupine last winter, I’ll be curious to know what this one’s home range is like.

The meeting place

A quick announcement, first off, for the folks who use Facebook and might be interested. Starting today I’ve taken over day-to-day management of the Peterson Field Guide fan page on Facebook. I’ll be posting photographs with associated bits of information. If this blog is, let’s say, mostly lunch- or dinner-sized servings, the Facebook items will be snack-sized tidbits. The content will be otherwise largely similar, though. If you’re a Facebook user and want to follow my posts there, go to this page and click on “Like” at the top, and it’ll show up on your Facebook friends page. And if you’re not a Facebook user but still want to check in, I’m pretty sure you can go to that link and it’ll still show you everything even if you don’t have a Facebook account.

And a second announcement, regarding the Nature Blog Network. We (or, I should say, primarily the hard-working Wren of Wrennaissance Reflections) have been planning a reinvigorating of the NBN blog and community. One of the things NBN members indicated they’d like to see was an RSS feed of all of the posts from the NBN members’ blogs. Something similar to that Blogger sidebar widget what will show you the latest posts from a person’s blogroll contacts. The feed was launched today and can be found here. A Google Reader version containing complete posts is here. If you’re a Twitterer, new member posts will be tweeted at the NBN Twitter page. Unfortunately, blogs have to be added manually (we couldn’t find a bulk import option) and with over 1200 blogs in the NBN it’ll take a little while to get everyone added, but they’ll all get there eventually! It’ll be a great way to find new and engaging nature content.

Procupine? trails

I’ve noticed just recently a proliferation of trails in our meadows. They cut through the long grass, flattening it down with the creature’s passage. They criss and cross and double back and come together. Can you see them, in the photo above? Two trails, leading out of the forest and converging in a compressed patch of grass. A meeting place? Friendly hellos, or irritated confrontation?

I don’t know for sure who they’re made by, but I suspect porcupines. I came across a little pile of the distinctive macaroni-shaped droppings at the side of our human-made trail, where a creature-made trail intersected it, a few days ago (discovered primarily because Raven was rolling in it, otherwise it might have escaped my attention). Also, I think it’s more likely these trails were made by a low-bellied animal such as a porcupine or raccoon than by something taller like a coyote or a deer. When Raven wades (bounds) through the grass, or even, for that matter, when I do, we don’t leave such a distinct trail. Grass stands back up fairly quickly from a swishing-through, but takes more time to recover if it’s been flattened.

I’m not certain why there would suddenly be such an apparent exodus of porcupines from the forest just now. It’s possible that youngsters, who to this point have been able to share feeding territories with their parents, are now dispersing to find their own den sites and associated winter feeding grounds. Or, maybe it’s just a single individual or two who’s taken a liking to the shrubs growing in the field, and has been making trips back and forth and between plants.

Porcupine? trails

(I was photographing a moth in the dark forest and set my camera to Manual mode while using the flash so the image wouldn’t get washed out. And then I forgot to change the setting back. So this image got washed out instead. I still like it, though.)

Out to lunch


There are, of course, lots of birds around at Innis Point. That’s the whole reason we’re there, after all: to monitor the birds. What I wasn’t expecting there to be lots of was porcupines. Spring is their season, the time of year when they’re most likely to be encountered, although I’m not exactly sure why this is the case, since they’re active year round. Even still, prior to this year I’d only ever seen the odd one here or there, and most of them tended to be in the form of roadkill, sadly. I spotted one in our own woods while out with Raven last week (fortunately, she hadn’t seen it yet and I steered her the other way before she had a chance to; Dan came across one with her a couple days later and wasn’t so lucky with the timing, though he was still able to call her away before she actually made contact with it), but have just seen the one. Out at Innis we’ve seen them every day. One day there were as many as four of them spotted around the site. One of them was especially laid-back, allowing me to approach within a couple dozen feet while it calmly continued foraging. I guess it has a lot of confidence in its protection.


They’ve mostly been up in the big, gnarly oak trees. They clamber along the thick, sturdy limbs, reaching out to the little twigs to snip the tender green buds off. Their hands seem to be remarkably dexterous, reminding me a lot of the fingered feet of raccoons.


They reach out with their broad paws to snag the twigs and bend them back to where they can easily reach the buds. Check out the long, thick claws. They and the rough pads would be useful in gripping the tree as the animal clambers about. Also for hauling that huge bulk straight up the trunk. On my way back from the washroom one morning I heard a rustling in the underbrush and spotted a porc approaching in my direction. It hadn’t seen me, so I stopped and watched it for a few minutes. It wandered to a small line of young trees, approaching the base of each and giving each a good sniff as it decided whether it was worth climbing. It passed by two trees in favour of the third, which was of a different species. I found it fascinating that it could apparently tell the difference just by smelling the trunk.


Porcupines are rodents, and one of the obvious features that they share with members of the group is the evergrowing, sharp orange teeth; they’re not dissimilar from beaver teeth. Since part of their diet, especially in winter, consists of the inner bark of tree trunks (which requires chewing through the outer bark to get at), these teeth come in especially handy.


When the twigs were too long for simply bending the branch to bring the buds within reach, the porcupine put its teeth to good use. It would bend the twig down…


…and then chew through the twig to remove it from the tree. Then it would manipulate it with its hands and snip off the buds before finally dropping the denuded twig.

I’ve written a bit about porcupines before, discussing their ecology a bit more in-depth. You can find previous posts here, here and here.

Tracking the porcupine

Trail to porcupine den site

I took Raven over to the 100-acre woods this afternoon. I hadn’t been over there in a little while, except for a quick hike through one day without camera or binoculars (I know, I know – you’re asking, why would I ever go for a hike without my camera? Sometimes, I guess, I just like to enjoy the forest for itself, and leaving the camera at home gives me more freedom to do that. Something like that, anyway.). The south portion of the property is completely forested, while the north end has open meadows chained together. There are access points at both sides of the property, one from the road, on the south, and the other from the rail-bed trail, on the north. Today I took the road, deciding I wasn’t really in a meadow mood. When I arrived I thought I would perhaps do a loop through the trails that stuck to the woods and return to the road entrance.

I started off according to plan. I headed down the west loop first, with the intention of taking that to one of the cross trails that would lead me to the loops on the east side. I got halfway down the west loop and then changed my mind. There was what looked like a small clearing set back from the trail, on the other side of some wild roses. Maybe I’d go check that out, and just cut through the forest to pick up the cross trail instead. So I changed course, pushed gingerly through the roses, checked out the clearing, and kept going.

And then, a short distance farther, I stumbled across the above, a very dirty track in the snow leading to a hole at the base of a dead tree.

Porcupine den site

Oh, what a fabulous discovery! My immediate first thought was that it was the nighttime den of a Snowshoe Hare, given the well-worn track that led right up to the doorway. It reminded me of the hare highways I blogged about a bit earlier this winter. I started to have doubts as I got closer, though. For one thing, the den was completely surrounded by, and filled with, the animal’s droppings. They weren’t droppings I recognized. Too big for rabbits, definitely too big for squirrels. Those of raccoons more resemble dogs or cats, and raccoons would be unlikely to be out and about anyway.

Porcupine den site

What was left? Porcupines? But they didn’t look like the porcupine poop I was used to seeing, either, which is a light sawdust colour, narrow, and curved like macaroni. Of all the droppings I know, these ones reminded me most of deer, actually – but there was no way a deer would fit in that little hole.

Trail to porcupine den site

I decided to try following the trail to wherever it led to, and maybe seeing if I could pick out any tracks on it along the way. It wound through some dense rose shrubs, which I decided to skirt around instead of push through, and then carried on through the forest. Eventually the trail led up to the large tree here. Recognize it? It’s the same tree that Raven discovered a porcupine in back in the fall. That pretty much confirmed the identity of the critter for me.

Below porcupine den site

At the base of this tree, more piles of droppings. These usually accumulate over the course of a winter underneath den trees or feeding sites, since the porcupine can’t be bothered going far when it’s snoozing. Dens are used through the entire winter, so the piles can grow quite large. They’ll break down over the summer, and will be nearly or entirely gone by next winter.

Below porcupine den site

There was a narrow cedar log propped up on one side of the big tree, with its own small pile of droppings at its base. I wondered if the porcupine would sometimes climb up using that, which was at a shallower incline than going straight up the tree. It might be possible that there are two (or more) porcupines denning in this tree, and one of them prefers the log while the other uses the trunk. Porcupines are usually solitary creatures, but if den sites are at a premium they’ll sometimes come together and share a den in the winter.

Porcupine den site

Just like at the first den, there are packed-down droppings right in front of the den’s door. In doing some research on the porcupine’s habit of defecating on its front stoop, I learned that the reason I didn’t recognize these droppings is that the shape of the pellets is diet-related. Tough bark makes up more of the porcupine’s diet in winter, and so the droppings are more compact; in the summer, when it incorporates more soft food like leaves or grasses into its diet, its droppings resemble those that I’d found before. I’ve encountered a few of these paler sorts through both this winter and last, as well, so presumably they’re the result of different diet preferences between individuals.

Eastern Hemlock boughs clipped by porcupine

There was another trail that led away from the big tree in a different direction from the one that I’d followed in. I decided to follow this one, too, to see where it went. Although I didn’t find this out until I came back home and poked around a bit, porcupines rarely travel farther than 100 m (300 feet) between their den and their feeding sites in the winter (summer ranges can be considerably larger). I figure the first trail I followed was about 60 m (200 feet) between the first den and the second.

After a similar distance, this second trail stopped at the base of a group of hemlocks that lined the small creek that cuts through the forest. Underneath the hemlocks were all these branch ends. I’d seen this before, and I’d just assumed that the poor trees had had a rough time of it in the last ice storm or something. Now I looked a bit closer.

Eastern Hemlock boughs clipped by porcupine

All of them appeared to be snipped off neatly. I learned, again after returning home, that here in the northeast Eastern Hemlock is a favourite winter food of porcupines, such that some will feed on it nearly exclusively. They chew on the inner bark of the trunk, but they’ll also forage on the needles and small twigs of the branches. Given that one doesn’t encounter many trees with their trunks chewed apart, my guess is that the branches make up the bulk of their winter diet. White Pine is another favoured species, which makes me wonder if the hemlock-feeders have the dark, compact droppings and the pine-feeders have the narrow, paler droppings. I’ve also seen some evidence in our little bog to suggest that at least one porcupine was feeding on the tamarack (also pale droppings there).

In my poking around, I turned up this video of a porcupine feeding on hemlock twigs, taken and posted by Dave at Via Negativa last winter. Check out the narrow little branch the animal decides to climb! It’s practically tightrope-walking.

I ended up using up my alloted hiking time tracking the porcupine, and I never did make it around to pick up the cross trail. After I’d found the feeding site I returned back to the trail I’d come in by and headed back home. However, during that short bit of wandering around off-trail I collected up a number of blog-worthy photos, so I’ll have some stuff to share for the next little while!

Tay Meadows Tidbit – Porcupine tree damage

Tree damage by porcupine

Well, that whole orchid kick got a little away with me. I hadn’t really intended to turn it into four posts when I found the helleborine stalks in the woods. And I cut myself short: I’m sure I could have rambled for a week on the subject if I’d wanted to. But I’m moving on now, to other things I’ve seen recently. On the same outing as I found the helleborines, I came across this tree trunk that had been gnawed away at by something. As I was stepping back to take a photo, Raven came over to check it out. She’s never one to pass up a photo op, whether invited or not. It does give you a sense of scale (she’s a 45lb dog). The damage extended about two feet (60cm) up the tree. It’s the work of a porcupine, which switch to bark as a primary staple in the colder winter months, when there aren’t green foods available.

The tree itself is a beech, so told by the smoothish gray bark, and it’s an oldish one. Judging from the diameter I’d guess it to be 60-80 years. It stands along an old fenceline, presumably the original fences from when the land used to be clear, and the forest has grown in around it again. I’ve noticed a few such trees in the forest. Damage like this on a smaller, younger tree might kill it, but this mature individual will likely just seal over the wound and keep on truckin’. Just like when you’re feeling stressed out, though, it will weaken the tree while it pulls through and make it more susceptible to diseases or other stressors such as caterpillar outbreaks.

It’s interesting to note that there are two colours to the damaged area. The upper part, a small band across the top, is a lighter, brighter colour than the lower part. This suggests that the damage was done in two stages: the lower part was the porcupine’s first visit, and then it came back a day or two later, after the first part had already started to dry out, and chewed off a bit more.

Tree damage by porcupine, with sap-loving flies

The porcupine would have chewed off the outer bark, which is tough and not very nutritionally useful, to get to the softer inner bark. The inner bark also contains some of the tree’s network of food transport tubes, called xylem and phloem, which like our veins move nutrients and oxygen throughout our body, contained within our blood. The outer bark acts like the tree’s skin, protecting the inner tissue. The damage exacted here by the porcupine is not dissimilar to if we fell and scraped our knee. The skin is peeled back to expose the soft tissue underneath, which then bleeds because the network of blood vessels has been torn. Before the tubes “clot” shut, some sap is lost, making the wound feel tacky, just like a scraped knee would be as it clots. It was a moderately warm day out, by mid-November standards, and a few flies had been attracted to the sweet sap on the recently-damaged part.

Tay Meadows Tidbit – Porc in a Tree

Raven, just wants to play

A couple of days ago we had some nice sunny weather, so for a break I took Raven down the road to the 100-acre woods. Raven was feeling her oats and all over the place. I decided to strike off off-trail to wander around and see what I could turn up. So often you encounter things that you either wouldn’t have noticed from the trail, or don’t happen to be near enough to the trail to be seen. This happened to be one of them. Raven had hurried up into a swath of deciduous trees, mostly maples, not far ahead in the forest. I thought I could hear the sounds of something climbing up a tree, and thought perhaps she’d cornered a raccoon. As I drew nearer, I just caught a glimpse of a prickly porcupine butt disappearing into a hollow in the huge maple. Despite trying to tell Raven that she wouldn’t have a lot of fun playing with a porcupine, and the porcupine didn’t want to play with her, besides, she continued to stand at the edge of the tree and whine (which is how I know it’s a “I want to meet you!” and not “What the heck is that scary thing??”, which elicits some barking, or “Omigod something evil is coming this way!”, which causes her to puff up her hackles and growl; she doesn’t seem to have a setting for “I don’t want you here, go away or I’ll chase you!”, at least that we’ve ever noticed).

Back in the spring Dan and I encountered a porcupine in Frontenac Provincial Park that scurried up a tree and sat, allowing me to get a few shots. Comparing those photos to this individual, it looks like this guy may have had a run-in with something else recently, perhaps a coyote or somebody’s dog. Its rump and upper tail are missing all the pale-coloured quills that are its primary defense, leaving a dark brown patch. After a few moments waiting in the tree cavity hoping we’d go away (we weren’t, I was trying to find a better vantage point where I could get a photo of the fuzzy bit of quills poking out of the cavity, since I’d missed getting a photo of him going in), he decided perhaps he would be a bit safer higher up in the tree, and hauled himself out again to climb up a bit farther. We left him alone after snapping this photo, much to Raven’s disappointment. If you’re interested in more of the life history of porcupines, visit my spring post.

Porc, very much doesn't want to play

Porc and pine


So I started out yesterday not with the intention of posting about the new Frontenac Bird Studies MAPS program, but rather to write about this guy, who we startled as we were hiking through the bush. We were far enough off the trails, and the trails are infrequently hiked to begin with, that there’s a good chance that this particular individual almost never saw people, and was probably quite alarmed when we came over the hill. He scurried over to the nearest tree and quickly started hauling himself up the trunk.

It is, of course, a porcupine. More specifically, it’s a North American Porcupine, Erethizon dorsatum. There are 27 species of porcupines, found in both the “old” and “new” worlds. In the Americas, there are 16 species, most of which are found in South America. The only one to occur north of Mexico is this one, which is mainly a northern species. It also happens to be the largest of them all, growing up to 40 lbs (18 kg), an adaptation to the colder climate. Most are smaller, since they live in warmer regions – for example, the prehensile-tailed porcupines of South America are only about a foot long and weigh less than a kilogram (around 2 lbs).


Our “neighbour” at the north of the lake told us to be on the lookout for them, as this is “porcupine weekend”, so I wasn’t entirely surprised to find it. It was, in fact, the second one we’d seen – we’d already startled one shortly after we’d started out from the car. That one disappeared after cresting a hill, and must have either gone into a den or behind some rocks or something. Porcupines spend the winter in dens, often in the ground. They do not hibernate, but do spend a lot of the cold months sleeping. As they start to get more active in the spring, you start to see more evidence of them.

Porcupine poop
Deer droppings and porcupine poop.

In particular, you’ll likely start noticing piles of their poop on the forest floor. The first time Dan and I found one we had no idea what it was. In the same way that you find little piles of rabbit or deer droppings, these were a pile of pellets, but pale brownish, the colour of sawdust, and shaped like macaroni. The sawdust colour isn’t all that surprising, as that is essentially the bulk of a porcupine’s diet. In the winter they mostly chew on the outer bark layer, denuding the trunks of trees but leaving the tree itself intact. However, they do also eat twigs and buds, particularly in the spring when there is tender new growth.


Those tender buds can get them into trouble. According to Wikipedia (which references a printed book called “The North American Porcupine”), porcupines occasionally fall out of trees in their attempts to get at these delectably tender new buds. This would be dangerous enough for the average animal, but is even more so for the porcs because they may fall on and stab themselves with their own quills. This is common enough, in fact, that porcupines have evolved to have an antibiotic coating on the quills which helps to prevent infection and speed healing.

This is also good news for Fido, should his curiosity get the better of him. The danger for Fido is more in quill tips breaking off under the skin, since these can potentially get infected. Like a fishing hook, the quills have microscopic backwards-pointing barbs that prevent the quill from easily being pulled out. However, if the tip does break off, it should eventually work its way out of the skin on its own, like a splinter might. A single porcupine might sport up to 30,000 quills, ranging in length from half an inch to four inches (1.2 to 10 cm), so it won’t miss a few dozen should it need to shed them in defense.


The quills are really just modified hairs, made of the same materials that form our fingernails. And like our hairs, they are controlled by tiny muscles in the skin attached to connective tissue around their bases. When these muscles are pulled tight, the quills stand on end, just like the hairs on your arm do when you’re cold. Porcupines have more control over these muscles than we do of ours, however.

Contrary to popular myth, porcupines can’t throw their quills, but they do release very easily. When the porcupine is relaxed and the quills flat, there is a fair bit of give in the connective tissue and muscles, but when tightened, the connective tissue tears easily. When a predator (or curious dog) applies pressure to the quill when it is standing upright, it pushes the quill backwards into the skin slightly, just enough to tear the connective tissue, which releases the quill from the skin. Studies have shown that it requires 40% less force to pull a quill out when the muscles are tight than when they are relaxed, a mechanism that helps prevent the porcupine from stabbing itself in climbing accidents.


Porcupines are rodents, and the North American Porcupine is the third largest rodent, behind capybaras and beavers. They have the same big rodent teeth that beavers do, and they put them to good use. Trees are their natural diet, of course, but of human wood products, they are partial to plywood, because of the salts added to it during the curing process. They’ll also target road salt used in the winter, both at the side of the road and where it accumulates on soft parts of vehicles.

And, of course, the answer to the question I know you’ve all been asking – how do porcupines mate? Well, let’s just say there’s not a lot of cuddling going on. The female, when she is receptive to a suitor, will curl her broad tail over her back. The underside is barbless, and if the male porcupine, who stands on his hind legs during the act, touches anything of the female it’s only the underside of her tail. On a related note, baby porcupines do have quills when born, but they’re soft, like your fingernails when you climb out of the shower. Within a few hours they have hardened enough to be effective protection.