It appears that the damage is being done by a pack rat. I need to do some more research. We’ve painted the tree trunk and wrapped the lower edge with tinfoil…and we’ve done some heavy cleaning. But no other sign of the culprit. The only thing we caught was a little mouse in the garage far from the backyard. We’ll keep looking — I’m not happy about a pack rat setting up residence in my yard…so close to pets and kidlets.