Train outdoor pets to keep away from bird houses: Behavioral conditioning with a water hose is an effective method that can also be used on squirrels and other wildlife with enough patience and perseverance. Pets should be supervised when outdoors during the nesting season as well, since young birds leave the nest several days before they can fly, making them easy targets for curious pets. Be sure the bird house opening is the right size for the species you wish to attract: If the opening is too large, predators will have easy access to the nest and other bird species may take over. A very large opening may also be dangerous for growing chicks, which could tumble out of the hole. A small hole could cause birds to get stuck, or they won't use the house at all.
Avoid bird houses made of metal. Metal houses will become miniature ovens in summer heat, and reflective metals are highly visible to predators. The house can have metal guards or trim over a different material, however, such as a metal cover to fix an entrance hole to the proper size if needed. Healthy Houses: Bird houses can become crowded as nestlings grow, giving diseases and mites greater opportunities to spread to young birds. A safe bird house is one that takes into account the health of the birds.