Yeah, I'd also considered Papillomavirus, as it does look a bit "warty" - although it looks closer to Scaly Leg that I've seen in Finches. Either way, it's feeding fine, and easily fights off other Jays over food. Not much I can do - it's too smart to catch. Although not apparent from this picture, apart from his posture (more squatting than standing), he's otherwise fine.
Obviously the main concern is the spread of the Mites or Virus - with illness or injury to Pigeons, I bring them in to either recover or die - but my eyes and reflexes aren't up to the task of catching a Corvid... at least not one that can fly*. From behaviour, favoured perch, reaction to me, I'm reasonably sure it's the same bird that's been like this since last year. No other birds are showing symptoms, so I'll just keep alert for any changes in the other birds.
(*It's not that Pigeons are less intelligent than Corvids (IME they're not), it's just easier to pick one out from a feeding flock of birds than to catch a lone bird.)