I have one black copper maran and 4 Barred Rocks. I am hoping someone will go broody because I would like to hatch a few more and really was unsuccessful hatching Black Copper Marans. How often will an "average" broodiness hen go broody. According to the site the Barred Rocks don't do it much but the Maran is listed as average. They are all about 20 months old. What can I expect??