Knocking in Montgomery County, Texas

On Monday, January 4, 2016, at 6 a.m., I was backcountry camping with a friend in the Sam Houston National Forest. We had made camp near an unnamed pond west of the Hiking Trail. The night was clear, 35 degrees, and perfectly still. My friend and I were hammock camping and, because of the cold, were both under low-staked tarps that prevented us from seeing out. Our hammocks were about 15 yards apart. At 6 a.m. it was still completely dark. I had been awake for about 15 minutes but remained in my sleeping bag inside my hammock. At that point I heard a sharp clack perhaps 75 yards on the other side of my friend. Two seconds later I heard a double-knock much farther away, perhaps a ½ mile to the north or northwest. The first pop was crisp and close. To my ears it had to be either rock on rock or wood on wood. As there is nothing in that area but sandy soil and trees, my conclusion was that this was a well-struck tree knock followed by a distant response. To the best of our knowledge there were no other people in the vicinity. We had arrived at the trail head to begin our one-night backpacking trip at 2 p.m. the previous afternoon, and we had only seen one other party of hikers, who passed our camp at 4:30 Sunday afternoon and continued eastward on the trail; we saw no one else during the entire trip, which ended when we arrived back at the parking lot at 11:30 a.m. Monday morning. Had it been windy I could have written the sounds off to cracking limbs, but there was not the slightest breeze, and the two sounds appeared to me to be a clear call and response, perhaps: “Humans over here" … "Roger that.” After the sounds, I froze and listened hard for several minutes for any other noise such as footfalls, stick breaks or other evidence of visitors but heard none. Within five minutes I asked my friend if he had heard it and he had not, having his ears covered by his cap and his head inside his sleeping bag at the time. Within 15 minutes we both were asleep again. We awoke for good at about 7:20 a.m. and vacated the area at 10 a.m. We heard distant coyotes, dogs, ducks, and owls, but no other such sounds during our stay. The absence of footfalls or other noises initially made me think it must have not been a sasquatch, but on reflection, the visitor could easily have frozen in his spot when he discovered our camp and then moved slowly away, perhaps using fallen logs, 15 minutes later once we were back to sleep. Considering the stillness of the night, the crisp, unambiguous clack, and the quick double-knock response, I can think of no other cause for these sounds.