Losing feathers

[Hollyschooks]

Hi, I have 3 Rhode Island Reds and one of them has been losing quite a lot of feathers for the past 3-4 weeks. It is acting normally, eating and doing the same as the others but it isn't looking too good. It doesn't look like the others are pecking it but it has lost a lot of feathers all over including the neck. Any ideas on what might be causing this?
Thanks

 

[prariechiken]

May be moulting....make sure it has no bugs, (mites) on it...