Bald spot at the base of their tail

[AnnJoyce]

I have 3 of my 11 hens that have a bald spot at the base of their tails. It is about 1-1/2 " in diameter. We do have a rooster but I never see him or the other hens pecking at them. The area is not irritated or red looking. When they molt do they lose all their feathers in one area like this?

 

[MeepBeep]

Highly likely the rooster is 'over' mating those 3 hens...