Hens go broody when you don’t want them to… and won’t go broody when you do. 
I have 11 hens and a young female duck, compliments of my daughter's Sunday school teacher. Right now she has a small kiddie pool to play in, but I've been wondering about building a pond. We don't have a huge amount of room. I don't know wether building a pond is worth it or if the pool is enough.
