Weird Feather on "Pekin" Duck

[Yorietran]

Hello all,

I am not sure what is up with my duck but he/she has these weird feather on since it was young. Nowadays, it's still there but it seems like it's "rotten". It has this black color (but my duck is white Pekin I think?)

I have included the picture down here. Wonder if anyone could help.

Back when he was younger

 

[chickens really]

That's normal and shedding the feather sheath.. definitely not rotten..