Functional birdhouse

I have designed a birdhouse for three different sizes of birds. It's not the most advanced design, but it's functional and takes into account the birds' different sizes and needs.I recommend printing it with PLA in colder climates and in the shade (note that PLA will change color over time) and with PETG in warmer climates and sunny locations (avoid direct sun). Most birds like their birdhouses to be around 2-3 meters above the ground.Please place the birdhouses 25 meters apart from each other. My birdhouses fit these birds:28mm hole size: Blue tit, Grey-headed chickadee, Coal tit, Marsh tit35mm hole size: Wryneck, Great tit, Tree sparrow50mm hole size: Nuthatch, Redstart, StarlingThere is also an optional third step that can be glued on behind the lid.Shouldn't there be a perch or similar under the hole? No, it does more harm than good. The perch makes it easier for predators to disturb our small birds. Boost MeBoost me if liked my design