Report 369: Possible vocalizations heard by backcountry hikers in Redwoods National Park

My friend and I were backpacking in the Redwood National Park, north of Eureka, on [a particular trail in the National Park]. We started hiking at about 3 in the afternoon, and hiked for a few hours. Then we walked off the trail up into a small canyon for about half a mile and made camp. Found bear tracks, started to get worried, so we hung our food from a tree. About this time (7 o'clock) we heard the first scream. It was short, and didn't repeat. We started to get a little freaked out, so we started a fire, and heard nothing for the next 3 or 4 hours. Then at about 10:30 11:00 p.m. the screaming started again, this time lasting for about 10 minutes. It sounded like it was about half a mile away on one of the surrounding ridges, a very eerie wail.  It didn't sound human.  I know what elk, coyote, and wolf calls sound like, and this was nowhere near... very similar to recordings I have heard of supposed bigfoot calls.  We went to bed at about 2 a.m., and left the next morning without incident.