Report 65779: Hunter describes trailer shaking then scream/howl outside Council on boundary of Payette NF and Boise NF

I had set up hunting camp on Sept 29 in preparation for the up-coming deer season which did not start until Oct 10.  On the night of Oct 7 something woke me up and I sat up in bed just in time for the travel trailer to start shaking rather violently.  I sounded an air horn that was sitting on the table and this had no effect at all.  I then grabbed my truck keys and pressed the panic button setting off the horn and the lights flashing, this stopped what ever was shaking the trailer.  After about 5 minutes I had calmed down when the God awful howl-growl-scream came from behind the trailer.  Really loud and had a terrifying impact on me.  Sixty plus years old at the time with years and years experience in the mountains and this truly scared me.  We tried to replicate the trailer movement the next day with a friend and I pushing on it but could do nothing more than give the trailer a jolt.  Whatever rocked the trailer had superhuman strength and the lung capacity to match.