Whooping in Humboldt County, California

I have spent a lot of time in the woods. I was a climber for ten years and I have heard it all out there. This was different. I was with my sons. We all wanted to camp in a bigfoot area, so we we went to a campground near Bluff Creek. We were all in the tent and in our bags, the camp had settled down and all of a sudden there was a whoop! They were loud as if behind us, in succession whoop whoop bah-whoop!! And it seemed that there was more than one, I estimate three, one to the left of us, one behind us, and one off in front at a distance. Also, something either took a large step or jumped off something, and it was big. The one behind us would call first and the one off in the distance would call back. The one to the left would whoop once, but the one behind would whoop three times and the others once or twice. At the start of the whoops would be almost a pucker or click sound. I figure the one behind us was the lead because he would call out and they would answer. After about ten minutes the lead creature started to move off with the one to the left towards the other. I wanted to look out the tent but my youngest was with me who is 6 and was real scared, because the calls were so loud. I stayed with him and did not get to look till it was over. I found no evidence in the morning, but earlier that day I noticed there were markings on a tree that was not made by a bear, almost as if the bark had been picked off. I have always followed this phenomenon and believed there was a possibility. This solidified everything.