Personally, I think it is number four. Just look at that thing - there is an owl face in the upper left, a gnome face in the middle, and some sort of bird/wolf creature on the right. This was clearly the work of a very skilled craftsmanbird, and given that two of the images happen to be of an avian nature, I suspect the woodpeckers. Every creature is partial to its own animal class, of course. I think owls must be like the superheros of birds, so naturally the woodpecker sculpted one.

Just a theory though. I could be wrong.