my husband purchased some muscovy ducks about a month ago; a drake, 3 adult females, and 6 ducklings. the adults all had messy plumage, and the drake was missing a lot of feathers. probably more than half, he doesn't have hardly any tail feathers and his whole chest is bare. we kind of assumed that this was due to the conditions they were being kept in and that the drake may have been fighting with other drakes. after watching them for a while, i realized that the adults were scratching themselves often, and also did this thing where they gently shake their wings for a while when they are standing around. i realized they must have some kind of parasite. they are not used to being handled, and since we just got them i didn't want to stress them so i haven't checked to see if i can see anything in their plumage. so far i haven't seen anything, and the ducklings do not seem to be affected. i also have geese and chickens and they don't seem affected. but my magpie drake now is scratching a lot and doing the wing shake. i have tried applying some food grade diatamaceous earth on their plumage several days in a row, hoping that might be enough. but it didn't seem to make a difference. based on the symptoms, what kind of parasites do you think this might be, causing a lot of itching and feather loss? they seem otherwise in good health.