Self-mutilation or pecking order - chewing off feathers?

[vermontgal]

I have a BR hen whose largest tail feathers are all nibbled off so that they are about 1" long. The feather ends are ragged, as though they have been torn off (chewed off). I find the ends of the broken-off feathers in the coop. This same chicken is low-chicken on the pecking order and is always sporting a feather-picked head. She is just about exactly 1 yr old, and has not yet molted.

Do you think she is chewing off her own feathers, or are the other 2 somehow breaking off her feathers? Any ideas on how to stop it?

Thanks for any opinions!

 

[onthespot]

google feather mites

 

[vermontgal]

I don't think it's mites. I've looked at her recently; I'll look again, but I think it is self-mutilation, like some parrots do. The large tail feathers are all chewed off to an even level about 1-1 1/2" long.

Googling feather mites, by the way, turns up relatively little useful information. I ended up googling chicken mites + extension which turned up some extension service publications.