I planted some roots just before our first (super-early) big blizzard. Hopefully it’ll grow. It speeds tissue regeneration and is good fodder for livestock, too. Research it—there’s a lot of probable exaggeration but it really does work IME, if your expectations are realistic.
I don’t know whether I d notice that on a few of my birds. All of them, and probably I would. Mine don’t like to be handled, so as long as they seem happy, I respect their wishes and just admire them without touching.
The tea tree oil sounds like a great idea. If it doesn’t work, I’d try...