Hi Arielle!Good question. Enquiring minds want to know.
Basic question. Bought a few birds from McMurray. Black cochins to play incubator. Among the three "black cochin", one of 3 males shows an area of brown feathers along his side. Other two do not. Trying to understand if this is a growth phase or a problem. No cochin SOP on BYC to ask.
Are you going to breed to a standard? If so, build the house and then paint it.
Go for conformation and then feather color. If the one with the brown feather looks close to whatever standard being used, then keep him for breeding.
Depending on age, he may molt out the brown at the last juvenal molt. Often cockerels do not get final feathers and color until then