I always knew that the flock block in the run attracted squirrels and chipmunks, but this morning I went out to refill the water in the run, and saw the biggest porcupine I have ever seen in my life. And I've seen a LOT of porcupines. He must have been in the run when I closed up last night. After I chased him out of the run with a very large snow shovel, I moved the flock block to the middle of the woods about half a mile from my house. "Spike" is now happily back up an oak tree a few hundred yards away from the chicken run. We'll see if he returns. If he does, I will have to resort to more drastic measures.