This is my first 5 months or so of doing chickens. Just got a rooster about a month and a half ago that I am assuming now is around 12 to 15 weeks old. I have not heard any crowing yet but this is what we are seeing. Today when we let them out of the coop after work, he ran across the yard and just pecked one of me pullets that is around 15 weeks or so in the back. Then he ran to another one of the pullets and mounted her. He was on her for about 5 seconds and then she shook him off and her hair bristled on the back of her head and she chased him a short ways. Then I saw him a little later run and peck another pullet about 15 weeks old in the back too. Is this normal rooster behavior or is this something I need to try to stop? Do all rooster behave this way? I don't want a mean rooster. I need some rooster education here.