Screaming or howling in Okanogan County, Washington

On Wed. 8/17/11 my family went camping in Okanogan County, Washington near the town of Conconully, WA. We arrived around 4:00 p.m. at the Salmon Meadows campsite. We checked out serveral sites and picked the one nearest the meadows, we were the only ones at this campsite. We went for a hike and got back to the campsite. There were numerous range cattle in our area. After hanging out at our site we heard a strange howl yell down in the creek bed the sound repeated 2 or 3 times, we were about 40 feet above the creek bed, we went down to take a look, we thought that an animal had injured itself. We found a young cow on the other side of the cattle guard. We opened the barb wire fence and tried to herd it to the other side, but it wouldn't go. We put the fence back up and went back to our camp. That night I woke up many times, thought I heard something and tried to see if anything was there in the full moon light illuminated meadows and forests. Our dog didn't react so I fell back to sleep hoping for morning. We woke up to some howls down in the creek bed below us. We had a video camera and tried to catch some of the howls on tape. We got 5 clips with the howls as they moved further away. I will email the best one after I submit this report. We tried to follow the sound away from us but it moved too fast, and our son was still sleeping in our campervan. We went back to camp and didn't hear or see anything else. We went to a bakery in Okanogan, WA and told of our experience and explained where we camped and all three people working said they had heard of this kind of activity around where we were. I have spent a lot of time in the woods and wild places, don't hunt or fish, and have never heard this kind of sound before. When we got home I sat down and wrote down a more detailed account, feeling like this was something significant.