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

Porcupine

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.

Porcupine

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.

Porcupine

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.

Porcupine

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.

Porcupine

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…

Porcupine

…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.