I'm at a loss. Tiny flock of 4 chickens - 3 hens, 1 rooster. Today will be the third and last of consecutive (weekly) permethrin treatments I'm doing to the coop and birds for what I'd suspected must be mites. But still today, it's only 1 - my rooster - who's losing feathers on a daily basis. I find about 10 feathers of his / day, and the area of his body on which feather loss is easily visible is at the base of his tail. (There was initially 1 other chicken losing feathers in that same area along with him, but it seems clear now that her long-standing bare spot is actually due to my roo mounting her - she's his favorite.) So now, what comes to mind is depluming mite. But wouldn't that spread to whole flock if it's affecting one of them? They all eat Layena layer crumble, have all-day access to the outdoors, and they do walk around and forage on a daily basis. Good energy, seem healthy, except that I did see dried poop bottoms on the rooster and two other hens, one of which has nver lost feathers during this whole process! Here are pics of Roo, taken a couple weeks ago, but the issue is still going on:
Roo is about 8 months old; I got him as a 4-month-old in March. Thank you!

