[Trot]

Not positive, but I think this is a fungus. Your local county agent should be able to help.

Meanwhile, you can apply Sevin dust, without any danger to your birds. It also will kill any lice which might infect them.

[Dacula]

I would NOT recommend Sevin. Use Diatomaceous Earth (food grade)

[Flaming Conservative]

Sevin dust? Won’t that get into their bloodstream? Can you eat a chicken dusted with that? (Full disclosure, I know very little about chickens, but I do know you can sprinkle them with food grade diatomaceous earth, and it will kill lice and mites, without harming people or animals.)