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.
Boreal Owls prefer mixed spruce_hardwood forests, while Saw_whet Owls prefer to nest near the edge of spruce or deciduous forest groves. Woodpecker nest boxes should be placed 6┰ feet above the ground, though Hairy Woodpeckers prefer nest sites 12 feet or more above the ground. Common Flickers nest in open areas and open park_like areas, while Hairy and Downy Woodpeckers prefer open deciduous forests.