The other day I was driving through the pasture and I saw a solo hen on the north side of a lone live oak that was about 12" in diameter on an open hillside. The wind was in my face so she did not see me until I was approximately 40 yards away. As soon as she saw me, she ducked and squatted behind the tree. The road took me about 15 steps from the tree as I drove due west. As I drove by the tree, I could not see the hen as she was moving around the tree to keep it between us. As I passed the tree, I barely saw her head against the ground, peaking to make sure I kept moving.
I have seen turkeys react in this fashion on several occasions but most of the time, there are multiples and when one runs or flies, seems all the others file suite.