Porcupines love bark? They have killed more than a couple of trees by eating bark and that's why I shoot them!
I've gotten a few P&Y porcupines also B&C while hunting over "rubs" or I like to call them "chew marks" like these.

No one's doubting your scouting skills, but the picture shows a few bizarre sightings, like the branches on the tree still attached (I count 9 nubbies).
Also rubs that appear to go into the ground, my experience has been around 1-4 feet is the normal, the height may be closer to 5 or 6 feet?