If there are more roosters and fewer hens, the roosters will fight each other to gain more hens. Alternatively, if there are too many hens for the resident roosters to cope with, they may become 'hen-pecked'. They will continue mating until they are too tired, and lose weight and condition. This lowers their fertility.

Why do roosters fight each other?

Cocks are armed with spikes

Cocks naturally fight with each other in the wild to establish territory or mating rights, but in these instances, serious injuries are rare as they back away and leave the area when they accept defeat.

How do you stop roosters from fighting?

Raise them together in your flock.

Roosters who are raised together establish a pecking order between them as they are growing up. Because they have already established that order, there is less incentive to fight when they are older and more likely to hurt one another by sparring.