raingarden
Crowing
Try introducing them if you haven't already. Sometimes having chicks elevates the hen's pecking order status. They are usually less likely to take any grief from the others.Mama is still a pretty new addition. I kept her in the cage for two weeks when we first got her. Shortly after letting her out, she started brooding.
A cheap beach umbrella that you stick in the sand can buy time to make something better.