I saw a group of six choughs in a tree building a nest on Red Hill. I saw at least four different birds involved in building this nest. The juvenile bird was also assisting. Each bird would fly in with wet mud, mixed with vegetation in the end of its beak. It would deposit the muddy contribution on the foundation then alternate the side of its beak to pat the mud down. The bird would pat along one side of the nest then turn its beak around before coming back down that same side of the nest under construction.