Report 7534: Sighting on Brazos River near Lake Whitney

My wife and I were out on the Brazos River with some friends. We were fishing and swimming on a sand bar in the Goatneck bend of the river. A member of our party noticed someone moving around on a rock ledge up on the cliffs about 250-300 feet above the river. They were about 1/2 mile away from us. As we started watching, whatever it was started jumping around, waving its arms like it was trying to get our attention. It did get our attention. It was jumping around like it was playing. We were able to observe it for 5 to 10 minutes. It jumped from one rock ledge to another that was 15 feet away and 20 feet or so down. A person couldn't have made that jump. It then jumped into a gully and disappeared. We waited a long time to see if it would reappear, but it didn't.