My bet, it's a porky. When you talk about those guys it's best not to ask why, you'll drive yourself crazy. Last Refuge I worked on we had an old elm tree, a survivor of the homesteaders, left all by itself way out in the middle of the prairie. One day I went by and the tree had been girdled. There was snow on the ground so there was no doubt it was a porky, but why did he think it was necessary to go a couple of miles away from any other tree and kill that pore ol elm tree.