Hens losing feathers above tail, not roosters

[crabby chickens]

We have 15 hens 23 weeks old, no rooster, they are laying well and appear healthy and happy. Some of them are rapidly losing feathers on their back at the base of their tail. We have seen no pecking and we don't think we see mites or lice. I have seen some crusty type skin in a few areas. Does anyone know what this is? Thank you

 

[Judy]

I promise you they peck each other -- it may not be really hard or cause injuries, but this is just what chickens do. The feather loss is usually from their picking or pulling each others' feathers, often eating them. Probably the main causes are too little protein and too little space / boredom. It can be a difficult habit to break if well established. Lots of threads on here about feather picking, including these from the FAQ page:

My chickens are pecking/eating each other's feathers:
https://www.backyardchickens.com/forum/viewtopic.php?id=34705
https://www.backyardchickens.com/forum/viewtopic.php?id=31291
https://www.backyardchickens.com/forum/viewtopic.php?id=36139
https://www.backyardchickens.com/forum/viewtopic.php?id=30486

You also may have a hen who has taken over the rooster's dominant role, and stands on others' backs as an act of dominance.