DarkFireFalcon
Well-known member
I still think it's staining, in this case. Perhaps from roosting/nesting in trees that are leaching tanins out of the wood onto their feathers. Given that you have a male and female visiting your feeder with the same condition, maybe they are both picking it up from the tree they are nesting in. That would explain the patchy nature of the yellowish coloration, and the fact that it covers most of the bird.