Thanks everyone and especially coloradochick for such detailed and useful advice. When my rooster, Bertie, (Sussex light I think) recently became aggressive I did all the wrong things I see! I got down on his level, I spoke soothingly and I hand fed him treats. Needless to say his aggression got worse. Tonight I tried it differently. I went into the coop in a big way, acted like I owned the hens, treated them first and wouldn't let him near the bowl till they had eaten, and got right up in his grill. What fun! He humbled right down. He is actually a timid and gentlemanly thing usually, but my oldest rooster, Monk, recently died, and he was the sweetest soul ever, but he never let this guy get away with anything. He was twelve and in great health until this killer winter. The old guy used to run and knock the young guy off the hens. Now I see I have to channel my inner Monk!