Naked Butt Chicken

[ShaySullivan]

My chickens have lost feathers on their butt and some on their backs. What could cause this?

 

[Kiki]

Mites would be my first guess.
Have you checked them over at night with a flash light for mites?

 

[KaylorFarms]

if your hen has irritated, raw, bald areas, especially near the vent, take a closer look for parasites. Pick up your birds and examine them closely