http://www.sciencedaily.com/releases/2009/12/091221212630.htm As big as a modern turkey.
Swoops down on you from behind.
"The prey would rapidly go into shock, but it would still be living, and it might have seen itself being slowly devoured". So the best you can hope for is that your head is turned away when you go into shock?
"Firehand" @ Irons in the Fire
http://elmtreeforge.blogspot.com/ thinks maybe #4s? No way! I'm going with nothing less than buckshot and a steel insert in the bill of my ball cap that I'll be wearing backwards covering my neck, thankyouverymuch!
Another reason not to go out in the woods. It's dangerous, I tell ya!
stay safe.