Feather problem

[RN chick]

I have only one of my chickens out of 10 with this issue. It is ruffled in the area right in front of tail feathers. I don’t see any mites or bugs. Please give me some help!

 

[Eggcessive]

Do you have a rooster or cockerel? It looks like it may be from feather picking or being overmated. What are they being fed including extras? Do they have enough room to roam around? Are they getting outside to free range?