Screaming or howling in San Jacinto County, Texas

[First incident:] It was approximately midnight in late April 2005 when me and three other friends were hiking in the Sam Houston National Forest. The weather was clear and the temperature was approximately eighty degrees. We had stopped to take a break and two of the three friends that were with me had gone up ahead of me and another guy. When me and my buddy were resting and talking about where we were going to go next we heard a long drawn out howl just like the Ohio howl on this website. I interrupted my friend and told him to listen. Approximately thirty seconds later we heard it again, identical to the Ohio howl. The howl lasted for about seven to eight seconds both times. The howls came from approximately five to seven hundred yards away through the woods. I have heard every variation of howl of every known animal in these woods and this sounded like no normal animal. My buddy and I caught up with the other two that were in the group and asked them if they heard anything strange, to which they replied, "No". [Second incident:] This incident occurred in the Sam Houston National Forest in late May 2005 at approximately midnight. A friend and I decided to go on an expedition of our own down near the east fork of San Jacinto River right off of FM 2025. We were approximately three to four miles off of the roadway down on the river in the thick of the woods. We set up and then waited to let the noise from us getting prepared die down. After about thirty minutes of silence I did the best impersonation of the Ohio howl that I could in a series of three, but got no response. We waited for a while longer and then I did it again in a series of three howls. And to our surprise, something hollered back at us that was within two hundred yards. It wasn't the same as the Ohio howl but it was a long loud deep growl, unlike a hog snorting, and it did this approximately three to four times. After it did that there was a long series of chattering noises that came from two different animals in front and behind us, but we never could see it. This went on for about one minute. My friend that was with me got instantly freaked out and jumped on his four wheeler saying, "come on, let's go, its right there!" I was able to convince him to wait and listen. We waited for approximately twenty minutes until we heard nothing but insects again. I told my friend to keep watch that I was going to try something that Daryl Colyer had told me about. So I picked up a stick about the size of a man's forearm and I hit it on a nearby tree about six times in a row then stopped. I did this three times in about a twenty minute span. After the third time, from the other side of the river we could clearly hear something that sounded just like what i was doing, banging a limb on the side of a tree and it sounded like it had some force behind it. Whatever it was, it did this about one to two minutes and quit. We waited a while and I hit the tree again as well as did imitations of the Ohio howl but never got another response. We waited a while but never heard anything but coyotes again after that. I guess it is possible for woodpeckers to be up between midnight and 2am, however highly unlikely. I had never heard anything like the chattering we heard that night that made our hair stand up. The low deep grunt/growls were not hogs and did not sound anything like hogs. However, we never actually seen them.