They Must Be Kept Clean

First and foremost your birds must be kept clean. Scrape the loft at least once per day and if you can, twice. The loft must be dry. It must be free of vermin, all vermin. If you can smell mouse, you have already lost! The loft should house less birds, never more. The loft should be adequately ventilated. The water should be changed ever day. Feed should never be present after the birds have eaten. Adequate quantities of minerals, grit, oyster shell, salt, etc. should always be present.