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.
Use the proper materials. Wood is the best material for birdhouses. Other materials (like metal or plastic) may not insulate the nest enough, so eggs or young could become chilled in cold weather or overheated in warm, sunny weather. Use rough_cut wood slabs, tree sections, or 3ǚ_inch plywood. Never use creosote_treated wood as creosote may kill the eggs or chicks.