How do roosters break their neck?

Answer 1

There are many ways for this to happen but, if the rooster is still alive and walking around it is possible his neck is not broken at all, that he is ill. There is a condition called "twist neck" and that could be brought on by a vitamin E deficiency. The bird will shuffle backwards with its neck stretched out and underneath its body.They will violently shake their heads and ruffle their feathers. Treatment for this is forced intake of a liquid vitamin supplement for about one week or longer.
As for a dead bird with an apparent broken neck, the most often cause is getting the head caught in the wire cage or fence, running from a predator and hitting something or a fight with another cockerel.

Answer 2

If the neck feathers are broken right off, and have kind of sharp edges to them, the rooster has probably been fighting. Another hint to whether it has been fighting, is if he had blood over his face, and looks a bit dreadful.

Another reason why he has broken off neck feathers would be because he has been molting. If you run your hands through his neck feathers (also called the hackle), and a whole heap of white-ish small round tubes, then he has been definitely been molting. He'll grow his feathers back either way.

Hope that helped! =D