Characteristics of a good birdhouse
Whether you purchase a birdhouse from a retail store or make your own, several factors increase the likelihood of successful fledging. Some bird box designs are known to improve the likelihood of hatching success, while others may contribute to the unfortunate death of chicks. A good quality birdhouse should have each of the following characteristics.
1. Rough Staircase or Textured Front Wall
Inside the front wall of every birdhouse, the chicks need a ladder or textured surface to sink their little claws into. They must be able to climb to the entrance hole to fletch. If your birdhouses are made of very smooth materials, it will be necessary to carve horizontal grooves, forming a ‘ladder’ for the chicks to climb. Simply make tiny lines about 1/2″ to 1″ apart, using a chisel, wood carving knife, or similar instrument, in a horizontal pattern from the bottom of the box to the entry hole. You can also attach 4″ x 4″ square window screen or other fine mesh with wood staples or carpenter’s glue. Just make sure the mesh isn’t too rough and the staples aren’t sticking out. If you use glue, make sure it is completely dry before allowing the birds to occupy the house.
2. Smooth and safe entry holes
Birds are diligent about keeping their feathers in excellent condition. Their lives depend on it. If the entry hole is irregular or has sharp bumps, this will damage the feathers every time a bird enters or exits the box. Run your fingertip around the entrance hole of your birdhouse. If you feel any roughness, sand it down with fine grit sandpaper. This should be done every year when you clean out the old nest. If the entry hole has been affected by a squirrel, you may be able to put a hole guard on top. These can be purchased or made at your own store by simply cutting a thin square of wood and drilling the appropriate sized hole inside it. Secure the guard over the old, damaged hole with screws, taking care to prevent the screws from penetrating the inside of the box, where they may present a feather hazard. Alternatively, you can attach the guard with carpenter’s glue.
3. Ventilation and drainage holes
Without a flow of air, bird boxes can get too hot or the air may be unhealthy for young birds to breathe. The intake hole itself does not provide enough fresh air, so you need to add some ventilation holes if they are missing from your design. Vent holes should be located near the top of the box, preferably below the protective edge of a protruding lid.
If the nest box has holes in the bottom, they are not for ventilation; They are for drainage. These are also essential. Drainage holes prevent the boxes from filling up with rain and help keep the nests dry if they get wet. Some species, like bluebirds, don’t mind if their nests get wet periodically. Check for holes in the bottom of the box. They can be located in the middle or in the corners. If there are no drainage holes, make them with a drill. Drain holes can be 1/8″ to 1/4″ in diameter. Sometimes the holes get clogged with nest debris, so make sure there are enough holes to allow for that possibility.
4. Roof seams properly sealed
A good birdhouse design shouldn’t have leaky roof seams, but don’t despair if you have one that does. If there is a roof seam that allows water in, it may be fine for bluebirds, as long as only a few drops of water get in during a heavy storm. However, if it rains heavily, the box can fill up faster than it empties, drowning or chilling the unlucky chicks. Inspect roof seams for leaks and fill with a bead of exterior caulking. Make sure the caulking is completely dry before putting it outside. Caulking or glue sticking to a bird’s feet or feathers can cause death.
5. Human access for cleaning
All birdhouses must be properly maintained. This can usually be done once a year, after the chicks have left. To do this, it is necessary to access the inside of the box, without having to disassemble or break it. Some decorative birdhouses may not have this feature as they are purchased more for ornamentation than practical purposes. The best designs open to the sides or front. This is easier for you and less dangerous for wild birds. When the floor of the box is the access point, there is a risk that it will accidentally open and dislodge the occupants. When the entrance is the roof, there is an increased risk of occupants getting wet in a major rain storm, although this is easily avoided by following the steps in #4 above.