Thanks all for the advice.
To answer some questions, he is a Buff Orpington, almost 11 months old. We bring him inside at night for about 15 minutes to feed him treats and get him used to being handled, then we put him back on the roost. He's easy to handle when he's sleepy which is why we're doing this at night.
The aggression started a month or two ago. He doesn't jump on me every time I come outside, more like 1-3 times a day (I'm in and out of the house a lot). It's worse first thing in the morning when I let them out of the coop and all he wants to do is mount the hens; he probably sees me as an obstacle. He also hates it when I give treats to his offspring, three juvenile cockerels whom we are rehoming this weekend. Even if I feed lots of treats to him and his hens first, he still goes after me if he sees me sharing any with the juveniles.
We picked a Buff Orpington rooster because it is supposed to be a mellow, docile breed. We don't need him to be cuddly or an indoor pet but we'd like him to be able to hang out nearby while we're using the back yard or taking care of the flock. It would be sad if we had to train him to stay away. He does not attack my husband but jumps on me and our roommate, even though our roommate walks in the same fast, assertive manner as my husband does. Interestingly, the rooster does not touch our little dog, even though she will occasionally snap at or chase a hen.
It sounds like there are different approaches to preventing and addressing aggression in roosters. I've read a lot of advice about picking them up and carrying them around under your arm, especially when the hens are around, to humiliate him and show your dominance. Then feed him treats, let him go, and give him more treats to share with the hens so he sees you as the source of good things both for him and for his girls. I've also read that consistently handling roosters as much as possible from a young age can help prevent aggression and get them acclimated to friendly interaction with humans.
Getting back to my original question, does anyone know whether chickens retain much of what happens when they're sleepy? Occasionally we'll do the same thing as I described initially with some of our more skittish hens, bringing them into the house for 10-15 minutes at night, to get them used to being held and feed them treats. If nothing else, I feel like getting both hens and roosters used to being picked up and handled should make it easier in the future should we need to provide medical care - and that time always seems to come sooner or later.
That boy that you raised is a STEW PIDASSO.. with attitude issues who is attacking the giant who brings him feed everyday. He doesn't see you as a threat, he see you as competition.
