Chicks, if you are counting this one, you don’t have three roosters, you have at least one cockerel. I have no idea how many pullets you may have. I also don’t know how your flock interacts. I’ll assume at least one male is a dominant rooster. There is a big difference in cockerels and roosters just as there is a difference in pullets and hens. Mature roosters and hens are normally fairly calm but cockerels have hormones running wild and the pullets usually don’t have a clue what is going on until they at least start laying eggs. Even then they may want a more responsible partner than a hormone crazed adolescent. Things often get wild when pullets and cockerels are involved. Mature hens often reject an immature cockerel, considering him not good enough to be the father of their children. They normally want a more responsible partner.
His chasing and mating is not all that much about sex either. When chickens mate the one on the bottom is accepting the dominance of the one on top, either willingly or by force. His chasing and mating is more about dominance than fertilizing eggs.
Since he was hatched in July, he is five months old. You can help dispel a myth, at least to yourself. I think you are already on board with this anyway. Take a good look at his leg. Count the number of spurs and observe how long and sharp those spur are. Then take a good look at his claws. Not toenails, claws. Count them and see how long and sharp they are. Watch when he mounts a pullet. Does he hold on by his spurs or does he hold on using his claws? The results are pretty much the same with an older rooster with a much longer sharper spur but looking at a five month old it’s pretty clear what is causing the damage. An older rooster’s spur is a dangerous weapon and it is possible that it could cause damage during mating if the hen resists and he forces her or his technique is really bad or if the hen is really barebacked, but the vast majority of feather loss is not because of the spurs.
With three males and 40 females you’ve already shown that the magical 10 to 1 ratio isn’t magical after all. Breeders often keep one rooster with one or two hens throughout the breeding season without any problems. People with much higher ratios sometimes see the problems you are seeing. The 10 to 1 does not stop roosters fighting, barebacked hens, or over-mated hens. It is simply a ratio that hatcheries use with the pen breeding method to ensure fertility. 10 to 1 makes a nice flock but the hatcheries have learned that putting say 20 roosters in a pen with 200 hen swill ensure practically all eggs will be fertile. It’s a fertility ration when using the pen breeding method, not a behavioral thing. With different management techniques it’s not even about fertility.
I don’t know how bad that feather loss is or if it is on hens or pullets. It is normal to occasionally have some feather loss during a mating, the problem comes when that feather loss is so great bare skin is exposed. Bare skin can be cut during a mating even if the rooster or cockerel’s technique is fairly good. Saddles may be appropriate.
I’m assuming the barebacked chickens are hens, not pullets, but I’m not sure. I’m also assuming you have at least one dominant rooster with the flock. Usually when a cockerel starts bothering my mature hens they run to the dominant rooster and he sorts out Junior. With the size of your flock they may be too spread out for that to happen.
I have had the situation where a hen was barebacked, not because of the rooster’s technique but because the hen’s feathers were brittle. No matter how gentle his technique the feathers just break really easily. That brittle feather thing is not extremely common but it’s not all that rare either. It’s normally a heredity/nutrient thing. An absence of certain nutrients can cause the feathers to be brittle. Due to heredity some hens’ bodies don’t process those nutrients like they should.
When I have a problem one of my first considerations is whether this is a flock problem or an individual problem. If it is pretty common across the flock I need to change my management. If it is an individual problem I treat the individual, not the entire flock. When I permanently removed the barebacked hen with brittle feathers it made my hen to rooster ratio worse but the problem went away and did not return in future generations.
Your problem is probably that cockerel. At five months his hormones are out of control, he has to resort to force since he is not mature enough to charm the hens, and his technique is probably not really good. The way I see it you have a few options. Since you said you don’t want to eat him, get rid of him. What happens at his new home is up to the new owners and flock dynamics if the new owner doesn’t eat him. When he is gone you have lost control of his future. You can try those saddles. They might work until he is mature enough to get his hormones under control and he matures enough that he doesn’t have to resort to force. You can try locking him up for a couple of months to see if he matures enough to behave with the flock. The downside to this is that when he rejoins the flock he and any other males of the right age will have to determine which is the flock master. With lots of room they normally sort this out pretty quickly and reach an accommodation on how they will work together to protect the flock, but when they fight there is always risk one could be seriously hurt or killed.
Good luck with it. Your situation is not unusual at all. Normally with time it sorts itself out but with hens that are truly barebacked there is risk.