I've gotten several calls lately about birds showing signs of avian pox.
Avian pox is harmless to humans, but for birds, particularly finches, it's highly contagious.
It may be indirectly fatal if it interferes with a bird's feeding or vision. Should you notice a bird at your feeder that seems to be afflicted with avian pox, stop feeding immediately. Discard any uneaten food that's left at the feeder. If one should show up again, repeat the above steps. Outbreaks of avian pox can most often be traced to overcrowding and unsanitary conditions at feeders.