Several of my hens have this same thing on the back of the neck but I figured it was caused by this guy, grabbing by the back of the neck when he mates. I was surprised a couple days ago to see the rooster has the same thing. It looks to me like feather have been plucked out but I've never seen one of the hens bold enough to do this to him. He, and the hens, are not loosing feathers anywhere else.
The other thing is the black on his comb. He won't let me pick him up so I can't look closely but this shot shows it pretty well.
My birds are all 8 months old and a first time with chickens so I figured I would ask the community here what is going on.
It was red, normal red. He had a couple points of the comb that went totally black but they are a bit better now. You can see second and third points from the back that are still a little black.
He's the only cockerel that you have?
How is your housing, plenty of roosting space at night?
Can you grab him up at night when he's roosting so you can get a better look at him?
Look through his feathers for lice/mites.
The black on the comb, to me, looks like injury. You mention that the pullets aren't bold enough to do that to him, well...just about any chicken comb is fair game during roosting time. Observe them then, it can be interesting to see the drama, the feather pulling/picking, comb twisting.
Observe you pullets with him during the day as well. Watch. He probably has 1-2 girls that follow him around or stay near. He likely is standing still and letting them pick at that comb some. A small nick/cut can turn quite large in a short period of time if they are picking at that. The white looks like it's just healing, that's the way it does.
You can try Blu Kote on the comb, but something like Pine Tar may be better if you see the girls picking at that. I had one rooster, they just would not leave it alone and he would stand there and let them pick at his comb until it bled. (he was getting attention) Nothing I tried worked until I separated him and let it heal.
Now the feather loss on the back of the neck is a bit more interesting. You got a picture of all of him so we can see his feathers? The girls too? I see some broken, some new growth coming in, but also seem some that look like they are nipped. Could be the pullets are doing that too but as mentioned, look him and the girls over for lice/mites.
