hens plucking feathers

[VanUnamed]

Hello, i have 21 hens of mixed breed, 5 of which are lohman brown. of those, 2, are plucking feathers off the others, i had to separate them from the rest.
Why they do this? No other hen does it.

 

[CluckerFamily]

Is your flock molting? Feathers have more protein to help get through the molting.

 

[aart]

How old are birds, in months?
What all and how exactly are you feeding?
How much space do you have in coop and run,
in feet by feet or meters by meters?
Dimensions and pics would help here.