Porcupines don't eat wood, only the bark and inner bark of the tree.
They will too eat wood. Used to have one that would eat on our barn, seen it several times.
I spent a summer in a remote USFS fire station. We lived in an old CCC barracks that was elevated about 3-4 feet above ground level and open at the bottom. A porcupine started gnawing under where the latrine was at night to get at the salt. Took about a week of nightly visits and chases to shoot it. It was smart.......would chew away until he heard the noise of guys waking up inside, then he would hightail it ahead of the posse. On his final night, I slept outside and when the ruckus started, I spotted him hauling arse to and under an old shed.
