Can someone tell me what is causing this

[StaatsFarms]

can someone tell me what is causing this. 4 out of my 10 hens have this on their backs. i initially thought it was from the roosters but, they have been gone for a couple months now and it doesn't seem to be growing back in

any help would be appreciated

 

[PortageGirl]

Won't grow back till moult time when they grow all their new feathers.

 

[Beekissed]

I agree...and it seems, if little pen feathers start to grow out, another hen will pick them out. After moult you will see new and pretty feathers again.

 

[StaatsFarms]

yeah, i have noticed the feathers look like they are starting to grow back in and in a few days they are gone