Knocking in Elmore County, Idaho

While mule deer hunting in Idaho, I road my atv to the snow line on road 255 southwest of Atlanta. I passed a truck with Alaska plates. It was parked on the side of the road with no one around just where the snow started. I was forced to turn around due to deep snow about a mile from the truck up hill from it. I observed many large elk tracks in the snow so I decided to move down in elevation to glass the timber strips. Elk season started in 3 days so I want to see if any were in this area. Once at the location about a half mile down hill past the truck, I parked on the side of the road. About 5 minutes into my search I heard a knock to my right about level with me about 300 yards away (guess). Very loud and solid. I first thought it was two trees hitting each other from wind. The wind was light though. About 5 minutes later it happened again but the knock sounded different and a bit lower. Within 10 minutes the Alaska truck drove by me with just a driver. He headed down elevation from me. I continued to glass this area without a sound for a good 5 minutes. I heard a vehicle coming up the hill and that person stopped to talk to me. He was a friend of mine from my old home town in California. Small world. I knew he liked this area and was happy to see him. We started to compare our hunting apps on our phones. Come to find out he was camped about 1.5 miles from my camp. We talked for a few minutes and then a loud knock like I heard before. A bit closer and near level to us. He stopped mid sentence for a second and turned to the direction of the sound but kept talking. A truck came by with a family in it and stopped to talk. I told him the snow situation and he headed up. He returned within 5 minutes and headed down the road to lower elevation. We heard 1 more knock lower and like further away (not as loud) after the truck passed us. My friend said, "What the hell is that??" I joked, "Bigfoot!" He immediately said it is someone splitting wood. When we heard 3 more in the next 20 minutes I told him that wood cutter sure takes his time between splits. Then it happened....a knock behind us with a different tone and it seemed farther away.. Then another below and to our right but not as loud as the other knocks. Things went quiet for 10 minutes. We said see you later. He headed up the road toward the snow line. It didn't take long and he was back and drove by me with a wave. I have not talked to him since then. Within 5 minutes of him driving by me I heard 3 distinct quick clacks or knocks directly behind me up the hill. Like rock not wood. Then 1 faint wood knock below me. I stayed for about 15 minutes in silence, then left.