That's a lot of roo for 12 girls. They'll be miserable with all the advances all day long. As a chicken owner myself may I suggest picking out two roos for the stock pot. 1:12 is a good ratio for flock health and well being.
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
I agree with James. For a week it might be teenage flirtations and awkward crowing. But pretty soon it will be the hens running ragged as they get jumped over and over.
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My experience has been that 3 roos keep each other mostly busy and the hens get a lot more free time. Regardless of how it goes, I'm pretty sure I can identify and rectify issues. I am very familiar with helping roos transition to the pot phase.
A piece of land is worth as much as the person farming it.
-Le Livre du Colon, 1902