Going to lead with: no, this isn't a skinwalker story.
Back in the early 2010s, my friends and I would hold regular airsoft practice in the woods behind my house. A lot of it was the sort of dense, old growth that covers to southeast US. Our last practice back there, we were wrapping up when we heard a very distinct whistle. We figured it was probably one of my neighbors who might have gone back to see what we were up to, so we called out to them, and, after getting no response, whistled back at them. We got another whistle back within ten seconds, and while we could figure out a general direction the whistling was coming from, we couldn't find anyone there. Getting a little concerned, we called out again, and decided to just pack up and leave when we got no response again.
Everything seemed mostly normal while we were packing up, though two of the people in our group insisted that they'd seen a figure peeking out from behind a tree at us. It wasn't until we were leaving that things got a little more exciting. On the way up the trail, my friend's dog kept indicating to the same area of to our right. We also heard that whistle every few minutes, getting closer each time we heard it. My friend with the dog later insisted that he saw a dark figure ducking out of sight from just behind us and off to the right of the trail. Thankfully, that's about the point where we started coming to the edge of the woods, and the events mostly stopped. The whole time that we were packing everything in the trucks, though, my friend's dog was laser focused on the woods.
I had some other kinda weird stuff happen at that house, like something hitting the back wall so hard that I thought the refrigerator had fallen over. To this day, my friend who claims to have seen it is sure we encountered something paranormal, though I'm not convinced that the whole situation wasn't just a bunch of college guys getting freaked out by someone in camouflage having a laugh.