What exactly causes a hen to go broody? Is there anything I can do to encourage a hen to go broody (I know you can't force them to go broody, but maybe I can help her out a little...)? My flock consists of Buff Orps (people say they are good broodies, but in my experience they rarely ever go broody), a Black Australorp, and a Partridge Rock with various roosters (no doubt the eggs are fertile!)