Allow to air dry. Once or twice a month should do, but weekly cleaning may be needed if you notice sick birds at your feeders. Use good food - Discard food that smells musty, is wet, looks moldy or has fungus growing on it. Disinfect any storage container that holds spoiled food as well as the scoop used to fill feeders. Prevent contamination - Keep rodents out of stored food.
Mice can carry and spread some bird diseases without being affected themselves.
Act early - Don't wait to act until you see sick or dead birds. With good prevention, you'll seldom find sick or dead birds at your feeders. Spread the word - Encourage your neighbors who feed birds to follow the same precautions. Birds normally move among feeders and can spread diseases as they go. The safest birdfeeders will be those in communities where neighbors cooperate with equal concern for the health of the birds.