young chicks loosing feathers

[carters farm]

my chicks are almost completely feathered out. however, there are 6 out of 13 that have naked shoulders and some have lost feathers on the back of their necks. Is this a pecking issue?

 

[ChickenCanoe]

Perhaps they are going through one of their adolescent molts.

 

[Battlepants]

Any blood on any of them? Or just missing feathers at this point?

Additionally, what are they being fed? Including any treats.

Also, what is their current age?