javas pulling out each others feathers

[klwklw]

would someone know why my juvenile male java is over preening his patrner so much she is bald on the back of the head now.they get on very well though.i also caught her pulling at some of his wing feathers today and they come out.they are both moulting into adult plumage so im wondering if this baldness on her is due to moult or is it his fault?opinions apppreciated.

[Buzzard-1]

What size cage are they in?

[klwklw]

theres 2 pair in a cage 30" long and 18'' wide and 30" high.theres no other birds in there.they dont seem to do it maliciously its almost like a play act.they are in a quiet area inside in a bright sunny room.they bath all the time,i give them greens regularily,and vitamin powder weekly.the male is 4mths old and sings all the time,all birds eat together and sit pretty close too.beats me!!!

[finchbreeder]

Could be too small, a cage? Have only ever kept them in a minimum of 1.8m H x 2 m L x 1.8m W for a trio.
LML

[Buzzard-1]

Why I asked cage size was first thing that came to mind was boredom specially with young birds.sounds like it may be a problem.

[klwklw]

thanks for replies,i will look at getting a bigger cage for them.