A few years back an adult rooster came to live on the farm. He was purchased from a flea market mostly out of pity because he had a healed leg injury that resulted in a limp. It did not seem to affect him too terribly much; he still got around fine, albeit a little bit slower than the rest of the flock, and his gait had a hitch to it that gave his movement a sort of lumbering quality. The plan was to give him a place to live out his days ruling the roost, and he did just that.
He also proved that he was not incapacitated by his injuries. His ability to catch up to a human and spur them was fully intact despite his bad leg. On many occasions he left people bleeding, but his attacks always came by surprise. Someone would walk around the corner of the house or barn and get a bloody surprise when the rooster nailed them. I never once was the victim of his attacks, however. I am not sure if this was as the result of luck or vigilance, but I was always on the lookout for him and believe it paid off.
Was I lucky, or just assertive? Years spent around horses have taught me to use body language to my advantage. I tend to puff up, looking big and scary as well as getting loud when trouble comes my way. If a horse acted up, I stepped towards the problem rather than away. I am inclined to think this benefited me when it came to the troublesome rooster. He was always around and had to have seen me in action, deciding that I was too crazy to engage. One of my counterparts who was not a horse person was attacked endlessly by this rooster. This man was not privy to the same big and bad style of body language as I was, and I think that was his downfall. He did not come off as dominant and thus he was attacked with regularity and frequency...until he picked up a stick.
A good way to nip this type of behavior in the bud is with a stick. Do not beat on your rooster, but simply tap him in the rear end lightly when he advances upon you or moves in a direction you do not wish him to go. The goal of the stick is to train your rooster to move directionally away from it. You can do this by using the stick as an extension of your arm and gently pushing him where you want him to go. After a few times of doing this, your rooster will learn what is expected of him. Soon you will not need the stick at all because he will develop an avoidance behavior at the sight of you as the rooster will have come to see you as the alpha animal in the pack.
It has been suggested that you pick up an aggressive rooster and hold them upside down to solve aggression issues. This is dangerous for the animal because it can cause choking or suffocation and should only be done at your own discretion with full awareness of the risks you are taking. The lungs of chickens and roosters are located in such a place that they can collapse when the bird is held upside down, resulting in death, so holding birds upside down is not advised.
To keep harmony amongst the flock, everyone needs to get along, including humans and roosters. What you want is a respectful rooster, not one that fears you, as that fear can spread amongst other animals, making them harder to handle. Remember that a good rooster watches over his flock and alerts them to danger-you do not want to be the danger of which he warns. Firm but gentle rooster handling will convey to your bird what is and is not acceptable and always be sure not to run from an aggressive rooster as that encourages pursuit. Repetition and consistency are important as occasionally reminding your rooster of his role in the flock, but with a little bit of time and patience, you will ensure a harmonious co-existence free of fear between you and your rooster.