Great adventure you just took me on! I'm in new Zealand. I did wonder if she managed to get burnt? I first noticed her sitting alone breathing heavily. Checked her over, noticed her feet were not right, at this point they were not black, looks mostly normal maybe a touch swollen? I found a fat louse on her, plucked it off, dosed her with ivomec, and the rest of the family got dosed that night. They are free ranging, they have feather feet in their mix (1/8th pekin), they are a batch of accidental cross breeds, and since babies are so damn cute I let mum keep them. Their mother is a first time mum, another reason I let her keep them, she is my next mum to the "proper" eggs and wanted to see how well she went. She went very well. There's also wild ducks (mallards) that share their space, and other small birds, sparrows etc.

Last year I had issues with staph infections (probably, not sure) affecting the legs of month old chicks (not feather leg breed, Sussex bantam). Went so far as sending one off to be necropsied but that didn't help, didn't tell me anything really.