About 5 of my 7 have some form of missing feathers on the back and a couple are losing their fuzzy butt feathers. No signs of mites.??

[Allybird]

 

[Allybird]

No rooster, clean coop with sand in the coop and straw in the run. One hen does have perfect feathers!

 

[nuthatched]

The one hen with nice feathers is picking the rest.

 

[LaFleche]

No rooster, clean coop with sand in the coop and straw in the run. One hen does have perfect feathers!

She is the culprit.