Porcupines leave plenty of signs where they have eaten the inner bark, or cambium layer, of a tree. Bark is missing on the trunk of the tree, leaving fresh, yellow wood exposed, which often bears incisor marks. An observation I have made over the years is that porcupines often de-bark around or near their hollow tree dens. Typically, if a tree den is used year after year, they gnaw off bark each year, sometimes eating the old, scarred portion which, due to previous chewing, lacks cambium cells. This has led me to wonder whether fresh de-barking in the vicinity of their tree den entrance might have more, or as much, to do with a porcupine’s staking out a claim on that tree than with its sustenance. I have never come across any research that even mentions this phenomenon, and would welcome feedback from anyone who has.
Typically, male porcupines spend days at a time up in eastern hemlocks, eating the tender buds and leaves of branches, while females tend to spend the day in a den, and head for nearby food at night. In the photograph, a porcupine den tree is on the left, with scat from the den having fallen on the snow below. The trail you see was made by the porcupine, as she went from her den tree to a nearby feeding tree. Usually a den is chosen within a short distance of food, as was this one. If you look closely at the uppermost quarter of the photograph, you will see a sign that indicates recent porcupine activity – nipped hemlock branches in the snow, that have been discarded by a porcupine, who’s feeding in the branches up above them. It’s much safer to remain on a large limb and pull the desired tip of a branch in to you than it is to attempt to climb out on a thin branch. Once the porcupine nips the tip of the branch off and eats the tender buds and leaves, it drops the branch to the ground below.
Birds and mammals that rely on beechnuts as a staple of their diet include black bears, white-tailed deer, fishers, porcupines, wild turkeys, ruffed grouse, wood ducks, tufted titmice, and numerous small rodents, to name but a few. There is a good reason for this – beechnuts have about the same protein content as corn, but five times the fat content. Beechnuts also have nearly twice as much crude protein and twice the fat of white oak acorns and about the same fat content as red oak acorns. Given the number of husks and nuts that are on the forest floor this fall, it appears that this is a good year for beechnut mast, or seed production. Research has shown that high beechnut production in the fall is correlated with a high percentage of reproducing female black bears in the coming winter.