I have no idea what it is. I can't even describe it. I've never heard it before. It only occasionally does a single scream/call. Once it let out a double scream. I wish my neighbor would quit mowing, so I could hear better. The woods are about 40 acres and it's not really close. My first thought was, "What the heck was that???" My next thought was, "Great, some new predator!" I've lived here around 20 years, so I'm kind of surprised to hear something unusual. Sure, now that I'm typing this, it quit.