Feather picking, moulting, mites can all cause feather loss. Are your roosts set far apart enough so that birds can't pick at each other? Do you let them out at sunrise, and lock them in at sundown? leaving birds cooped up for too long with limited space can cause feather picking, behavioral stress. The best time to check for mites is in the evening when birds are roosting. Take a flashlight and pick up a few birds, checking each one's vent, under wings, along the belly. Mites are usually dark or red colored specks about the size of a pin point that move along the skin. Feather mites burrow into the quill of a feather and some burrow in the skin near the base of feathers. This causes chickens to become irritated and pull feathers.
Use a permethrin concentrate for spray labeled for mites and lice like Permectrin II or a Rabon-Vapona concentrate like Ravap EC. Treat all the birds by parting the feathers around the vent, along the back, and belly as you spray. A hand-pump sprayer works well for this. Be sure to follow mixing instructions on the label for either product. You can also use Sevin-5 dust by putting a few handfuls in a sack, place the bird in the sack with its head outside the sack and pat the bag to get dust airborne in the bag. Some people cut panty hose and put dust in it for patting the bird down along it's body. Again, it is important to part feathers as you do it like when using a spray. The problem with dusts is you have to do it again 7-10 days later for eggs that have hatched. With the sprays I mentioned, you do not.
It does no good to treat the birds and not treat the housing. All shavings must be removed from nests and floors. Get up all dust remaining with a broom or shop vac. Use a pump type yard sprayer to administer the pesticide mix. Again, follow all safety methods according to label instructions. Spray down the walls, tops, bottoms, and sides of all roosts, floors, nest boxes, and all cracks or crevices. Give solution time to penetrate wood to mostly dry, and put new shaving back in the coop. The birds can then have access to the coop. It is a good idea to do this 3-4 times a year. It may seem laborious because of the details, but it is easy and prevents infestations so your flock will remain mite and louse free.
Mites and lice can cause anemia in addition to stress, so it would be a good idea to supplement water with a good water soluble vitamin-mineral, and probiotic powder in waterers 3 days a week in addition to a well balanced feed ration. Avian Super Pack and Probios dispersible powder are a couple of good quality water supplements.
