Report 70716: Knocks and responses heard near Muskrat Cove campground, Moraine State Park

It had to be the summer of 2015, 16 or 17.  I was camping with my sons’ troop in Moraine State Park in Butler County, PA.  I woke up in the middle of the night.  I want to say it was around midnight, but cannot be sure.  This would have been a Friday night into Saturday morning. I was taken back by how quiet the woods were.  Being a seasoned tent camper, this struck me as odd.  Our tent was the closest to the shore line, maybe 30 or 40 yards of woods in between us and the shore.  The deep woods were on the other side of a trail road from our tent site. Up the shore line I heard what sounded like a tree or rock knock.  The knock continued for a little bit and was eventually answered by other tree knocks coming from two distinct locations in the deep woods.  The answered calls seemed pretty far in the distance but still auditable.  The original knock came from our side of the shore and was closer than the other two.  This happened for a little while, the answering calls never changed, but the knock on our side kept getting closer to our tent site. I was actually astonished at how fast the knocks where moving down the shore line.  By that I mean, the knock source closest to us was coming toward our camp site, working its way down the shore line.  Whatever was making the knocks was moving at a good speed for being in the woods at night. Then the knocks stopped right when it felt like the source was directly behind us. The following night was Saturday. I woke up again, but this time the woods were their normal sounding self and there was boat life on the lake.  I did hear another knock, fairly distance in the woods, but that was the only one.