They will, but not until he molts. I'd eventually try to wash his feathers off. You might wait until you're sure he's fully healed that way you don't end up dislodging any scabs and reopening any wounds. If he's nice enough to let you catch him you could try giving him a little soak or wiping him down w/ a wet washcloth. If he's not then it will likely wash off in the rain eventually. Personally, I'd try cleaning him up a little just to keep any others from noticing that he's different or getting the taste of blood.