Reading the last few has reminded me of a story from when I was about 15. I was visiting a friend of mine that I grew up with in a mountain community of Colorado at about 9,000 ft (location withheld so nobody shows up at one my best creepy experience spots).
It was a beautiful September day and my friend's parents had taken us into town to run errands and have lunch. We decided on a whim to walk back to their house instead of ride back with the parents. This was about an 8 mile journey that took us all afternoon, and to shorten our walk at one point we decided to cut across part of a large piece of an old private ranch that as far as we could tell then was unoccupied. There was an old ranch house that looked very run down but was otherwise a wide open valley with dense forest on all sides and perfect looking Elk habitat. As we were ascending an open mountainside through this property we passed closely by an island of Aspens approximately an acre in size. When we got to within about 75 yards of this aspen stand we heard the loudest most blood curdling scream I've ever heard, followed by large branches breaking, and the sound of something large just absolutely thrashing about in there. We stopped walking and stood there for maybe 3 seconds before breaking into a sprint up to the ridge. Once to the ridge we started descending a steep downfall ridden north facing slope at speeds that were unsafe and we are lucky to have not been hurt. We stopped when we had finally reached the dirt county road in the next valley. To this day I remember the scream and the incredible anger and volume. Most vividly though, I still remember not feeling safe at all in broad daylight. It's actually one of the few times I can remember feeling like my life was just threatened, and I could be in real trouble. Not a good feeling at any age. Whatever made the scream was clearly directing it at us as we were talking loudly and walking out in the open and clearly came too close to its Aspen stand. We were only 15 to be sure, but we had grown up exploring the woods, hunting with our dads and encountering bears and other wildlife so we weren't complete outdoor idiots. That area has since been acquired by the county it's in and turned into a popular open space with biking and hiking trails, but back then it was a very seldom if ever visited area.