Barefoot tracks and whistling heard while hunting witnessed in Yakima County, Washington

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First of all I don't know if this incident is a big deal or not, but I been a outdoorsman for many years and it kind of caught my attention. I was Elk hunting in the Bumping river area of Yakima County. I was walking up the American ridge trail in the am Hours. I had reached a portion of the the trail that was flat and had soft dirt. I noticed a foot print on the trail. My first thought was why would someone walk barefooted up on the mountain. The track was not large. It looked like a slender womans foot print. I followed the track up the trail for about six to eight feet and I then lost sight of the track. I continued walking and I heard a wierd whistling sound. It wasn't real loud, but I definetly didn't recognize it. I started to put things together in my mind (Track/Whistle) and the hair on the back of my neck stood up. I continued up the trail and eventually sat down to watch a draw for any elk that may be crossing. I again heard the whistling sound. I have been huntin...