A few minutes ago, a bit before 1 AM, I was on my front porch doing some nitrocellulose lacquer spray painting (as one tends to do at these hours). At this time of night the local environs tend to be pretty quiet, with nothing but the wind – if there is any. So imagine my surprise when there was a sudden noise from the cluster of trees across the road. How to describe the sound… hmm. You know in the monster movie when Our Heroes are in the forest either hunting the monster or being hunted *by* the monster, and the monster starts moving through the trees, making big *crunching* sounds as it shoves branches and such out of the way? Yeah. About like that. Don;t know what it was, but it sounded sizable. Of course, on a silent night it may well have been nothing more than a raccoon or three moving through low dry brush, but it *sounded* the size of a bear.
I think there’s something in our evolutionary background that makes us a little sensitive to the sound of a largish critter moving through foliage. A few hundred thousand generations of Home Erectus getting gnawed upon by lions and wolves and such might’ve ground that sensitivity into the human gene code.