very interesting, thanks for sharing.
I once had a mixed hen (bantam x standard breed) who was the best broody hen I ever had. She raised countless hatchery chicks for me. NOTHING messed with her chicks, she even told me so a couple times and the exchange was very personal. ;-)
I saw her take on a red tail one day. He swooped in on her brood, she collided with it breast to breast about two feet off the ground. The hawk ate the ground she flogged the thing with death in her eyes. The hawk then took off and for good measure she grabbed two or three tail feathers as a souvenir and chased him a good 20 yards for good measures all the while cussing him to high heaven.