Hello, I posted a thread on my chicken cats unusual symptoms and I recently noticed my chicken Chumi has the same problem! Here are some pictures and there is more information on my previous thread.
The photos in both threads are hard to see. Can you please take clear well lit photos of the spots so we can offer some suggestions.
If your hens are molting, what you see may be dandruff or keratin sheaths being shed from emerging feathers.
If the spots are alive and moving like bugs, then you've got cause for concern.