When I was about 11 years old, living in Madison, in southern West Virginia, in the early 1970s, the kids in my neighborhood played a game on summer nights called "Indian Trapper." It was sort of a team hide and seek game.
One night I was hiding beneath a medium-sized tree, the top of which was about 25 or 30 feet off the ground. I remember distinctly there was a full moon and it was a very bright night.
Hearing something, I looked up and saw silhouetted against the moon a giant bird. It's wingspan had to be twenty-feet or more and it's head looked something like drawings you see of prehistoric birds. It was gliding on a slow descent toward a nearby river.
I never spoke of it and then a couple years ago started thinking about it again. I thought perhaps time had altered my recollections and it probably was not as big as I remembered, but then I read accounts on the Internet of other sightings during the 1970s in Pennsylvania and West Virginia. I'm now sure that what I saw was a Thunderbird.