That missing leg surely involves an accident, those missing feathers may be mites, but now we have a male Northern Cardinal with what looks like a tumor on his head:
It’s not obvious in that picture, but the black patch seems to be the rubbed-raw top of a growth.
Prior to these birds, in all the years we’ve been birdwatching we’ve never seen any damaged cardinals…
The Smell of Molten Projects in the Morning 