Knocking in Grays Harbor County, Washington

It was July 2002, I was picking wild black berries that are native to the area, and found mostly on back logging roads. While picking the berries on the end of a spur road that cut across a hill side I heard what was wood knocking, It sounded like two pieces of hard wood being knocked together, the first time was three knocks in rapid succession one after another then a pause and some more knocking, it was very unusual. I have been in the woods all of my life. And have heard grouse thump, Elk call, and bugle, and deer snort and even bark at you. But have never heard something like this. The spur I was on is West to East, East being the end of the spur where I was picking the berries. After hearing this wood knocking, I walked West back up the road and could tell the knocking was coming from the ridge above me. I thought it had to be coming from another human being because nothing else could make a noise like that. Banging two pieces of wood together had to be a human event. BUT I was out in the middle of the forest. At least 7 miles from the nearest house and only one house at that. I had been up and down all the surrounding roads and spurs already picking berries and knew there were no other vehicles in the area, so no one else was out there, I was alone. So what could it be? I had no clue I wanted to climb the ridge to investigate but it was very steep and very thick with dog hair, or second growth hemlock. So I decided against that, The wood knocking continued as I walked back to the truck, It was to a little strange so I just left the area. Later I learned that wood knocking is suppose to be a habit of Big Foot, So now it makes more sense to me that the sound was coming from a big foot. And not another human out there in the woods were it was unlikely for another person to be and messing with me. What else could it have been...