I was a bit south of the Canadian Border and I had hit the bag in my pup tent for the night and I was drifting off. Then I heard a loud blast of air, kind of sounded like that T-Rex in Jurassic Park the movie. The first thing I thought was a PO'd moose had snuck up and he was going to turn my wigwam into loose threads. Then just a few seconds later the same blast but further away from the tent. And no footstep sounds!.... Much too tired from humping the hills that day, I went back to sleep. Made inquiries on that with various game people later, and a bird expert said their best estimate was that it was an owl. They can make wierd sounds. Cracked me up. Well, I am not convinced about Bigfoot but I find the notion entertaining.