By a flying squirrel! Lol. Dad and I were hanging stands today and he climbed up to take the stand down. Well he noticed a rip in the back rest. And there was a little nest in it. No sooner, I spotted a flying squirrel on the tree right next to him just a few feet away. It was pretty cool. This thing wild leave us alone. So we take the stand down and begin putting the steps up the other tree (I was moving the set up about 20 yards away to a better tree) and I see the squirrel on my stand on the ground. The thing picked up a baby that was inside the stand! it was still alive, and the momma picked it up and carried it back to the tree we just took the stand out of. It was an awesome experience!